| By Author | [ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | Other Symbols ] |
| By Title | [ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | Other Symbols ] |
| By Language |
|
Download this book: [ ASCII | HTML | PDF ] Look for this book on Amazon Tweet |
Title: Encyclopedia of Diet - A Treatise on the Food Question, Vol. 1 of 5
Author: Christian, Eugene
Language: English
As this book started as an ASCII text book there are no pictures available.
*** Start of this LibraryBlog Digital Book "Encyclopedia of Diet - A Treatise on the Food Question, Vol. 1 of 5" ***
[Illustration]
ENCYCLOPEDIA OF
DIET
_A Treatise on the Food Question_
IN FIVE VOLUMES
EXPLAINING, IN PLAIN LANGUAGE, THE
CHEMISTRY OF FOOD AND THE CHEMISTRY OF
THE HUMAN BODY, TOGETHER WITH THE ART OF
UNITING THESE TWO BRANCHES OF SCIENCE IN THE
PROCESS OF EATING SO AS TO ESTABLISH NORMAL
DIGESTION AND ASSIMILATION OF FOOD AND
NORMAL ELIMINATION OF WASTE, THEREBY
REMOVING THE CAUSES OF STOMACH,
INTESTINAL, AND ALL OTHER
DIGESTIVE DISORDERS
BY
EUGENE CHRISTIAN, F. S. D.
VOLUME I
NEW YORK CITY
CORRECTIVE EATING SOCIETY, INC.
1917
COPYRIGHT 1914
BY
EUGENE CHRISTIAN
ENTERED AT
STATIONERS HALL, LONDON
SEPTEMBER, 1914
BY
EUGENE CHRISTIAN, F. S. D.
ALL RIGHTS RESERVED
PUBLISHED AUGUST, 1914
TO THE
MOTHERS
AND TO THE NOBLE WORKERS
IN THE GREAT CAUSE OF HUMAN HEALTH
AND OF HUMAN SUFFERING
THESE VOLUMES ARE
Dedicated
BY
THE AUTHOR
PREFACE
Countless centuries have come and gone and have left on the earth myriad
forms of life; but just what life is, from whence it came, whether
or not there is purpose or design behind it, whether or not all the
sacred books are mere conceptions of the infant mind, of the whence and
whither, we do not know; but when we put life beneath the searchlight of
science, we do know that it is a mere assembling of ionic matter into
organic forms, and that this strange work is done in accordance with
certain well-defined laws.
We know that these laws are a part of the great cosmic scheme. In
harmony with them works evolution, which tends to lift to higher and
higher degrees of perfection all forms of both animate and inanimate
life. We believe that if all the natural laws governing life could be
ascertained and obeyed, the number of disorders or interferences with
Nature's scheme would be very greatly decreased.
Man's system of co-operating with his fellow-creatures, which we call
civilization, has imposed certain restrictions, duties and limitations
upon him, which make it impossible for him to live in strict accordance
with these laws; therefore if he would have his birthright, which
is health, he must employ science to fit him into his artificial
environment.
Man has been brought to his present state of physical development on
the rural, outdoor, close-to-nature plan, and since he must live in
houses and pursue occupations foreign to those through which he was
developed, he must make corresponding changes in the material from
which his body is constantly being repaired and made; therefore, as the
selections, combinations, and proportions of the various things he needs
for nourishment are determined by his age, activity, and exposure to the
open air, if he accurately or even approximately ascertains and observes
these things, life will continually ascend in the scale of power and
grandeur, and his endurance and period of longevity will be increased.
Nearly all forms of life on this globe, except man, live approximately
eight times their period of maturity. Man matures at twenty-four;
measured by this scale he should live about two hundred years. But the
average life of civilized man, reckoning from the age of six, is only
about forty years, while if we include the infant class, and reckon
the average age from his birth, he scarcely gets his growth before his
hair and teeth are disappearing, and his eyesight is being propped
up by the lens of the oculist, and he quietly drops into his grave.
One hundred and sixty years of life, then, is about what civilization
has cost him up to date. This is very expensive, but of course he has
something to show for it. He has aeroplanes, wireless communication,
the mile-a-minute train, politics, several kinds of religion, rum and
cocain, the tramp, the billionaire, and the bread line.
We cannot consistently leap over ten thousand years of heredity and
habit, but we can recover some part of the one hundred and sixty years
of life civilization has cost us. This can be done by feeding our bodies
according to their requirements determined by age, temperature of
environment, and work or activity; by cultivating mental tranquillity;
by loving some one besides ourselves, and proving it; by breathing an
abundance of fresh air, and by doing useful work. Of all these things
food is the most important because it is the raw material that builds
the temple wherein all other things dwell.
Civilization and science are doing but little real good for man if they
cannot select for him the material necessary to develop his body and all
its faculties to their highest degree, or at least free him from much of
his disease and materially increase his "ease"; they have brought him
but little, I say, if they cannot show him a way to live more than forty
years. Science would have nothing of which to boast if it only pointed
out a way by which man could exist for two hundred years, as this is
his birthright. It can only boast when it has given him more than his
natural heritage.
That man's general health and period of longevity have decreased, while
all other branches of science have so vastly increased, is evidence
sufficient to justify the assertion that he has not employed scientific
methods to the art of living, or at least to those fundamental
principles, such as nutrition, motion, and oxidation, which really
govern his health and his life.
The difference between youth and age, between virility and senility,
is in reality a chemical difference only. The difference between the
flexible cartilage of youth, and the stiff cartilage of age is one of
chemistry.
If, by the process of metabolism, the muscles, bones, tissues, and
brain-cells can be made to multiply and to reproduce themselves at
eighteen, it seems only logical that science should give us the secret
by which this same thing could be done at eighty, and if at eighty, why
not at a hundred and eighty? It is by no means extravagant to say that
if science can teach us the actual demands of the body under the varied
conditions of age, climate, and activity, and the means of supplying
these demands with only such food elements as are needed, life can be
prolonged to what seems to be our natural period of years.
Consider the human body as a machine that possesses the power of
converting fuel or food into energy, using or expending that energy at
will, reproducing itself piece by piece from the same fuel, and casting
out the debris and ashes--if all this is done by the body automatically,
and its power to act or to do these things depends so completely upon
the fuel or the material with which the body has to work, then the
question of the _kind_ of fuel, the quantity, how to select it, how to
combine it, how to proportion it, becomes at once the most important
problem within the scope of human learning.
THE PURPOSE OF THIS WORK
When we compare man's longevity with other forms of life, and consider
that he breathes the same air, drinks the same water, lives under the
same sunshine, and that he differs from them chiefly in his habits of
eating, the conviction is forced upon us that in his food is found the
secret, or the causes of most of his physical ills and his shortened
life. All elements composing the human body are well known. Its daily
needs are matters of common knowledge. Science has separated the human
body into all its various chemical elements or parts, and weighed and
named them; it has also analyzed and separated his food or fuel into
its various chemical elements or parts, and named these. It would seem,
therefore, a most logical step to unite these two branches of science,
and to give to the world the dual science of Physio-food Chemistry, or,
what I have named Applied Food Chemistry.
The sciences of physiological chemistry and of food chemistry can be
made useful only by uniting them--putting them together--fitting one
into the other for the betterment of the human species. These two
branches of science can be of use in no other possible way except
by ascertaining the demands of the human body through physiological
chemistry, and by learning how to supply these demands through the
science of food chemistry. In the union of these hitherto separate
branches of science I can see the most useful, the most important, and
the most powerful department of human knowledge. It is this union that
these volumes are designed to make.
THE AUTHOR.
NEW YORK, _August, 1914_.
CONTENTS
VOLUME I
_Page_
PREFACE vii
_Lesson I_
THE INTERRELATION OF FOOD CHEMISTRY AND PHYSIOLOGICAL
CHEMISTRY 1
Food Chemistry and Physiological Chemistry United 3
Relation of Superacidity to Other Dis-eases 6
Chart Showing the Number of So-called Dis-eases Caused by
Superacidity 9
Natural Laws Demand Obedience 11
How to Make Nutrition a Science 14
Our Food Must Fit into Our Civilization 17
Why the Science of Human Nutrition is in Its Infancy 18
_Lesson II_
SIMPLE PRINCIPLES OF GENERAL CHEMISTRY 23
Chemical Elements 27
Air and Oxygen 32
Manufacture of Oxygen 33
Chemical Action of Oxygen:
(_a_) Upon Substances 36
(_b_) In Living Bodies 38
Hydrogen and Water 42
Uses of Water in Chemistry 48
Importance of Solution to the Food Scientist 50
Importance of Water in the Human Body 52
Uses of Water in the Body 53
Nitrogen and Nitrogen Compounds 58
Chlorin 63
Hydrochloric Acid 64
Acids, Bases, Neutralization, Salts 68
Principles of Neutralizing Alkalies 71
Fluorin, Bromin, Iodin 73
Mineral Sulfur 73
Vegetable Sulfur in the Human Body 75
Metals 76
_Lesson III_
ORGANIC CHEMISTRY 79
Carbon 81
Inorganic Carbon Compounds 83
Carbon Dioxid 83
Relation of Carbon Dioxid to Life 85
Carbon Monoxid 86
Organic Carbon Compounds 87
Classification of Organic Carbon
Compounds:
_a_ Hydrocarbons 89
_b_ Alcohols 91
_c_ Glycerin 92
_d_ Aldehydes and Ethers 93
_e_ Organic Acids 94
Organic Nitrogenous Compounds 99
_Lesson IV_
CHEMISTRY OF FOODS 103
Carbohydrates 107
Classification of Carbohydrates 108
_a_ Monosaccharids 109
_b_ Disaccharids 112
_c_ Polysaccharids 114
Fats and Oils 122
Proteids or Nitrogenous Food Substances 125
Mineral Salts in Food 131
_Lesson V_
CHEMISTRY OF DIGESTION 135
Digestive Organs and Digestive Juices 137
Saliva 142
Gastric Juice 144
Composition of the Gastric Juice 147
Bile 153
Pancreatic Juice 153
Intestinal Juices 157
The Secretion of Digestive Juices 158
Abnormal Chemical Changes in the Digestive Organs 165
The Decomposition of Food 173
Digestive Experiments 175
Mechanics of Digestion 180
The Muscular Movement of Digestive Organs 187
_Lesson VI_
CHEMISTRY OF METABOLISM 191
The Building of Actual Body-tissue 195
The Generation of Heat and Energy 197
The Measure of Human Energy 199
Metabolism of Carbohydrates 202
Metabolism of Fat 205
Metabolism of Proteids 209
The Use of Proteids in the Body 210
The Action and the Composition of Proteids 213
Food Standards 217
True Food Requirements 226
_Lesson VII_
FOODS OF ANIMAL ORIGIN 233
Meat 250
1 Flesh or Lean Meat 250
2 Animal Fats 254
Cold Storage of Meat 256
Contagious Dis-eases and Animal Food 258
Fish 260
Poultry as an Article of Food 262
Effects of Feeding Poultry 265
Eggs 269
Milk 273
The Adulteration of Milk 279
Milk Pasteurization 280
Cheese 282
Butter 283
Oleomargarin 285
VOLUME II
_Lesson VIII_
FOODS OF VEGETABLE ORIGIN 287
Grains 289
Uses of Grains:
(1) Grain as a Source of Energy 295
(2) Grain as a Source of Nitrogen 297
(3) Grain as a Remedial Food 298
Nuts 300
Peanuts 306
Legumes 307
Fruits 308
Classification of Fruits according to acidity 313
Vegetables 317
Classification of Vegetables 319
Sugars and Sirups 324
Beet-Sugar 325
Honey 330
Confections 332
Vegetable Oils 335
_Lesson IX_ _Page_
DRUGS, STIMULANTS, AND NARCOTICS 341
Alkaloids and Narcotics 349
Opium 350
Cocain 353
Nux Vomica and Strychnin 356
Quinin 356
Acetanilid 357
Tobacco 361
Coffee 363
Tea 365
Cocoa and Chocolate 366
Alcohols and Related Compounds 367
Alcohol 367
Chloroform, Ether, and Chloral 372
Poisonous Mineral Salts and Acids 373
Mercury 373
Potassium Iodid 374
Lead and Copper 375
Purgatives and Cathartics 375
_Lesson X_
IMPORTANCE OF CORRECT DIAGNOSIS AND
CORRECT TREATMENT 379
_Lesson XI_
COMMON DISORDERS--THEIR CAUSE AND
CORRECTION 403
Health and Dis-ease Defined 405
Overeating 413
Superacidity 418
The Cause 420
The Symptoms 421
The Remedy 423
Fermentation (Superacidity) 424
The Cause 425
The Symptoms 426
The Remedy 428
Gas Dilatation 431
The Symptoms 432
Importance of Water-drinking 434
Constipation 434
The Cause 434
The Remedy 436
Foods that May Be Substituted for One
Another 439
Constipating and Laxative Foods 446
Constipating and Laxative Beverages 446
Gastritis 447
The Cause 449
The Symptoms 449
The Remedy 450
Nervous Indigestion 453
The Cause 454
The Symptoms 455
The Remedy 458
Subacidity 460
The Cause 461
The Symptoms 462
The Remedy 463
Biliousness 465
The Cause 466
The Symptoms 466
The Remedy 466
Cirrhosis of the Liver 467
The Cause 467
The Symptoms 468
The Treatment 469
Piles or Hemorrhoids 471
The Cause 471
The Symptoms 472
The Treatment 472
Diarrhea 474
The Cause 474
The Treatment 476
Emaciation or Underweight 477
The Cause 478
The Symptoms 481
The Remedy 482
Obesity or Overweight 491
The Cause 493
The Remedy 495
Neurasthenia 503
The Cause 505
The Symptoms 506
The Remedy 506
Malnutrition 511
Cause and Remedy 511
Locomotor Ataxia 511
The Cause 511
The Symptoms 514
The Remedy 515
Colds, Catarrh, Hay Fever, Asthma, Influenza 519
Colds--The Cause 520
The Symptoms 521
The Remedy 523
Catarrh--The Cause 527
The Symptoms 528
The Remedy 528
Hay Fever--The Cause 530
The Symptoms 531
The Remedy 531
Asthma--The Cause 533
The Symptoms 533
The Remedy 534
Influenza--The Cause 536
The Symptoms 537
The Remedy 537
Insomnia 538
The Cause 538
The Remedy 539
Rheumatism--Gout 543
Rheumatism--The Cause 544
The Symptoms 545
Gout--The Cause 546
The Symptoms 547
Rheumatism, Gout--The Remedy 547
Bright's Dis-ease 550
The Cause 551
The Symptoms 551
The Remedy 552
Diabetes 556
The Cause 556
The Symptoms 557
The Remedy 557
Consumption 560
The Treatment 564
Heart Trouble 569
The Cause 571
The Remedy 573
Dis-eases of the Skin 574
The Cause 575
The Treatment 578
Appendicitis 580
The Symptoms 582
The Treatment 583
Chronic or Severe Cases of Appendicitis 586
VOLUME III
_Lesson XII_ _Page_
HARMONIOUS COMBINATIONS OF FOOD AND RECENT
DISCOVERIES IN FOOD SCIENCE 591
Chemical Changes Produced by Cooking 593
Starch Digestion--Cooked and Uncooked 597
Excuses for Cooking Our Food 599
Experiment upon Animals 601
Recent Discoveries in Food Science 603
Animal Experimentation 605
The Vitamines 607
General Conclusions 610
Protein 612
Mineral Salts 616
_Lesson XIII_
CLASSIFICATION OF FOODS AND FOOD TABLES 619
Simple Classification of Foods Based on
Principal Nutritive Substances 621
Purposes which the Different Classes of
Food Serve in the Human Body 625
Purpose of Carbohydrates 625
Purpose of Fats 626
Purpose of Proteids 626
Purpose of Mineral Salts 629
Difference between Digestibility and Assimilability 630
Table showing Comparative Assimilability and Carbohydrate
and Water Content of Cereals, Legumes, and Vegetables 632
_Lesson XIV_
VIENO SYSTEM OF FOOD MEASUREMENT 637
Energy 639
Nitrogen 641
Systems of Food Measurements Compared 642
The "Old" System 642
The New or "Vieno" System 645
Necessity for a Simple System 646
Explanation of Table 648
Table of Food Measurements 655
_Lesson XV_
CURATIVE AND REMEDIAL MENUS 665
Introduction 667
Cooking 669
Grains 669
Vegetables 670
Cooking en casserole 671
Rice and Macaroni 672
Fruits 672
Canned Goods 673
Buttermilk 674
Home-made Butter 674
The Banana 675
How to Select and Ripen Bananas 676
Baked Bananas 677
Recipes:
For Coddled Egg 677
For Uncooked Eggs 678
For Baked Omelet 678
For Fish and Fowl 678
For Green Peas in the Pod 679
For Pumpkin 680
For Vegetable Juice 680
For Sassafras Tea 681
Wheat Bran 681
Bran Meal 683
Choice of Menus 683
Normal Menus 685
Introduction to Normal Menus 685
For Normal Child, 2 to 5 years 687
For Normal Youth, 5 to 10 years 692
For Normal Youth, 10 to 15 years 696
For Normal Person, 15 to 20 years 700
For Normal Person, 20 to 33 years 704
For Normal Person, 33 to 50 years 708
For Normal Person, 50 to 65 years 712
For Normal Person, 65 to 80 years 716
For Normal Person, 85 to 100 years 720
Introduction to Curative Menus 724
Curative Menus:
Superacidity 726
Fermentation 753
Constipation 761
Gastritis 763
Nervous Indigestion 784
Nervousness 789
Subacidity 801
Biliousness 809
Cirrhosis of the Liver 822
Diarrhea 832
Emaciation 845
VOLUME IV
Obesity 870
Neurasthenia 897
Malnutrition 901
Anemia 905
Locomotor Ataxia 911
Colds 917
Nasal Catarrh 925
Hay Fever 931
Asthma 935
Influenza 939
Insomnia 940
Rheumatism and Gout 947
Bright's Dis-ease 979
Diabetes 983
Consumption 989
Dis-eases of the Skin 1013
Appendicitis 1029
Menus for the Pregnant Woman 1033
Importance of Food during Pregnancy 1033
The Nursing Mother 1040
Menus for the Nursing Mother 1042
Miscellaneous Menus:
Weak Digestion 1046
Building up Nervous System 1053
For Aged Person 1061
Strength and Endurance 1069
Malassimilation and Autointoxication 1074
No appetite 1081
Athletic Diet 1088
For Invalid Child 1098
For Mental Worker 1106
For School Teacher 1115
For Laboring Man 1122
For Cold Weather 1133
For Hot Weather 1134
To Build Up Sexual Vitality 1138
VOLUME V
_Lesson XVI_
ADAPTING FOOD TO SPECIAL CONDITIONS 1145
Infant, Old Age, and Athletic Feeding;
Sedentary Occupations, Climatic Extremes 1147
Normal Diet 1152
Infant Feeding 1154
General Rules for the Prospective Mother 1157
Special Rules for the Prospective Mother 1159
The Nursing Mother 1162
Care of the Child 1164
Constipation 1169
Exercise 1171
Clothing 1171
Temperature of Baby's Food 1173
Bandage 1173
Emaciation 1173
General Instructions for Children after One Year 1174
General Diet from Ages One to Two 1174
Simplicity in Feeding 1175
Old Age 1178
Three Periods of Old Age 1181
Athletics 1188
Sedentary Occupations 1194
General Directions for Sedentary Worker 1198
Climatic Extremes............ 1199
_Lesson XVII_
NERVOUSNESS--ITS CAUSE AND CURE 1209
Causes 1213
The Remedy 1217
Suggestions for Spring 1220
Suggestions for Summer 1222
Suggestions for Fall 1223
Suggestions for Winter 1224
_Lesson XVIII_
POINTS ON PRACTISE 1231
Introduction to Points on Practise 1233
Suggestions for the Practitioner 1236
Value of Experience 1239
Value of Diagnosis 1241
Educate Your Patient 1242
Effect of Mental Conditions 1245
Publicity 1247
Be Courteous and Tolerant 1250
_Lesson XIX_
EVOLUTION OF MAN 1253
What is Evolution? 1255
The Three Great Proofs of the Evolution of
Animal Life 1261
Man's Animal Kinship 1265
_Lesson XX_
SEX AND HEREDITY 1277
The Origin of Sex 1279
A Rational View of Sexual Health 1285
Embryological Growth--Prenatal Culture 1289
Heredity 1293
What Heredity Is 1295
Summary of Facts regarding Sex and Heredity 1297
_Lesson XXI_
REST AND SLEEP 1299
Rest 1301
The Old Physiology 1305
Rest and Re-creation 1306
Sleep 1308
Some Reasons 1310
Oxidation and Air 1312
_Lesson XXII_
A LESSON FOR BUSINESS MEN 1315
A Good Business Man 1320
The Routine Life of the Average Business Man 1322
Some Suggestions for a Good Business Man 1324
_Lesson XXIII_
EXERCISE AND RE-CREATION 1327
Exercise 1329
Constructive Exercises 1330
Exercise for Repair 1331
Physiology of Exercise 1333
Systems of Physical Culture 1338
Program for Daily Exercise 1343
Re-creation 1346
_A chest of miracles,
Close-packed and all secure, the unstable mass
Supported from a ruinous collapse
Or helpless flexion, by a spinous pile
Rigid as oak, yet flexile as the stem of the nodding flower.
Within, a nest of wonders, separate tasks
Each organ faithfully performing, still
From day to day harmoniously smooth
And uncomplaining, but for hindrances
Or ruinous urgence. Thou hast wisely said,
Melodious singer of old Israel,
"I am fearfully and wonderfully made."_
E. C.
LESSON I
THE INTERRELATION
OF
FOOD CHEMISTRY AND PHYSIOLOGICAL
CHEMISTRY
FOOD CHEMISTRY AND PHYSIOLOGICAL CHEMISTRY UNITED
The human body is composed of fifteen well-defined chemical elements.
A normal body weighing 150 pounds contains these elements in about the
following proportions:
POUNDS OUNCES GRAINS
Oxygen 97 12 --
Carbon 30 -- --
Hydrogen 14 10 --
Nitrogen 2 14 --
Calcium 2 -- --
Phosphorus 1 12 190
Sulfur -- 3 270
Sodium -- 2 196
Chlorin -- 2 250
Fluorin -- 2 215
Potassium -- -- 290
Magnesium -- -- 340
Iron -- -- 180
Silicon -- -- 116
Manganese -- -- 90
There are a number of other body-elements, but they are so remote that
they have not been clearly defined by physiological chemists. All these
body-elements are nourished separately, or, as it were, individually.
They must be replenished in the body as rapidly as they are consumed
by the vital processes, and this can be accomplished only through the
action of the elements, in the forms of food, air, and water, received
into the body and assimilated by it.
[Sidenote: Where 91 per cent of human ills originate]
From my professional experience I have estimated that about 91 per cent
of all human ills have their origin in the stomach and the intestines,
and are caused directly by incorrect habits in eating and drinking. If
this is true, or even approximately true, it shows that, in its relation
to health and the pursuit of happiness, food is the most important
matter with which we have to deal; yet the average person devotes far
less consideration to it than he does to the gossip of the neighborhood,
or to the accumulating of a few surplus dollars.
[Sidenote: Eminent writers agree as to importance of diet]
Profs. Pavloff, Metchnikoff and Chittenden; Hon. R. Russell; Drs.
Rabagliati, and Wiley, Ex-Chief of our Federal Bureau of Chemistry, and
many other profound thinkers and writers have given in their various
books an array of facts which prove beyond doubt that food is the
controlling factor in life, strength, and health; yet they have given us
but few practical suggestions as to how it should be selected, combined,
and proportioned, so as to produce normal health, and especially how to
make it remedial and curative, or to make it counteract the appalling
increase in disease.
I have endeavored to begin where the great theorists left off--
1 By becoming familiar with the chemistry of food
2 By becoming familiar with the chemistry of the body
[Sidenote: Food chemistry useless without body chemistry]
Until my work began these two great sciences had been taught as distinct
and separate branches of learning, while in reality _physiological
chemistry_ is but half of a science, and _food chemistry_ is, in fact,
the other half of the same science. The energy in food cannot be
developed without the body--the body cannot develop energy without food.
Each branch is worthless, therefore, without the other. In this work
I have endeavored to unite them and to make of the two one practical,
provable, and usable science.
RELATION OF SUPERACIDITY TO OTHER DISEASES
[Sidenote: Superacidity a primary cause]
Nearly all stomach and intestinal troubles begin with superacidity.
This is caused by the wrong combinations of food, or overeating.
Food passing from the stomach, thus supercharged with acid, causes
irritation of the mucous lining of the alimentary tract. This results
in nervousness, insomnia, intestinal congestion (constipation),
fermentation, and intestinal gas, while the excess of acid in the
stomach causes irritation of the mucous surface of that much-abused
organ, which develops first into catarrh, then ulceration, and sometimes
into cancer. The accumulation of gas from the fermenting mass in the
intestines causes irregular heart action, and sometimes heart failure.
The great number of sudden deaths from this cause is pronounced by
physicians "heart failure." In this the doctors and the writer agree--I
know of no other way to die except for the heart to fail. The primary
purpose of this work, however, is to ascertain _why_ the heart fails,
and, if possible, to remove the causes. From the fermenting food toxic
(poisonous) substances, such as carbon dioxid, are generated, which,
when taken into the circulation, become a most prolific source of
autointoxication (self-poisoning).
From long experience gained by scientific feeding, in treating stomach
and intestinal trouble, it became apparent that a great many disorders,
very remote from the stomach, completely disappear when perfect
digestion and assimilation of food, and thorough elimination of waste
are effected. This has led to a very searching investigation of causes,
and to the preparation of the following chart, which is designed to show
how a great many so-called diseases can be traced back to one original
cause--superacidity.
[Illustration: CHART, SHOWING THE NUMBER OF SO CALLED DISEASES CAUSED BY
SUPERACIDITY]
[Sidenote: Power to resist disease depends upon correct feeding]
Aside from emotional storms, great nervous shocks, inoculation
(vaccination), and violent exposure, nearly all diseases can be traced
back to the stomach, or errors in eating. Even in cases of exposure,
vaccination, or contagion, if the digestion and the assimilation of
food, and the elimination of waste are perfect, the body will have the
power to resist nearly all these causes of disease. Curing disease,
therefore, by scientific feeding, is merely a method of removing causes
and _giving Nature a chance_ to restore normality.
[Sidenote: Foods that ferment make inferior flesh]
Food that sours, ferments, or that does not digest within Nature's
time-limit, cannot make good bone and brain. A defective digestion that
converts food into poisonous gases in the intestinal canal will make
inferior flesh and blood, just as any other defective machine will turn
out inferior work. This is the natural law governing all animal life.
[Sidenote: Nature's protest against unsuitable building material]
Millions of learned people admit that good specimens of men and women
can be constructed only out of good building material. They admit that
the quality of a man, like that of a house, or a machine, depends upon
the kind of material used in his construction; and yet they allow this
important material to be selected and prepared by the most ignorant
and unlearned, and they take it into their bodies with a childish
thoughtlessness that is amazing; and when Nature imposes her penalty for
violating her laws, they seek a remedy in drugs and medicines, and these
are applied only to the symptoms which are merely the protest Nature is
uttering. Thus a powerful drug silences or kills the friendly messenger
who brought the timely warning, but the cause still remains. Suppose
houses, ships, and machinery were constructed and repaired after this
plan!
NATURAL LAWS DEMAND OBEDIENCE
Recompense for obedience to natural law, and punishment for its
violation, are the invariable order of the universe, and are nowhere so
effectively and emphatically demonstrated as in the cause and cure of
the condition called disease.
There are certain laws which, if obeyed, will build the human body to
its highest efficiency of energy, vitality and strength; but in order to
obey these laws, one must know them, and in order to know them one must
pass through the long and arduous mill of experience, or else learn from
one who has done so.
Pain is a warning that something is wrong with the human mechanism, and
he who tries to silence this signal with medicine will be punished for
two wrongs instead of one. Nature tolerates no trifling, no deception;
her laws are inexorable, her penalties inevitable.
[Sidenote: Treating symptoms instead of causes]
Multitudes of people are convinced that there is _something wrong_ with
their eating. Instead of food giving them the highest degree of mental
and physical strength, which it should do, it actually produces ills
and bodily disorders; moreover, not knowing the cause, people have
no conception of a remedy other than drugs. It is amazing when one
thinks how man, for two thousand years, has treated disease. Instead of
studying causes and endeavoring to remove them, he has treated symptoms
and symptoms only. It is generally known that the practise of medicine
consists in treating symptoms rather than causes. For example, nearly
all headaches--one of our common afflictions--are caused indirectly
by impaired digestion, faulty secretion and excretion, yet the drug
stores and Materia Medica (the Bible of the profession), are laden
with "headache cures," all of which act only upon the symptoms. The
whole system of drugging people when they are sick is merely a method
of quieting the signals--of killing or paralyzing the messengers. Most
drugs, taken into the human body, are merely diminutive explosives, the
effect of which is destructive. They are like a lash cruelly applied to
a willing servant who lags from sheer exhaustion.
[Sidenote: "Ease" and "Dis-ease"]
Since symptoms are really the language of Nature, if we learn to
interpret them, we need never err in diagnosis, and consequently never
err in getting directly at the causes, as we must do in order to
"cure." A drug that could _cure_ a disorder caused by wrong feeding
would perform a miracle. _It would reverse one of the fixed laws of the
universe. It would produce an effect without a cause._ Nature works
along the lines of least resistance, and points out with unerring
certainty the best, the cheapest, and the easiest way to live. Health
was originally called "ease." People who did not have health were in
disgrace or "dis-eased."
HOW TO MAKE HUMAN NUTRITION A SCIENCE
Human nutrition cannot be made a science under the conventional methods
of omnivorous eating--eating anything and everything without thought or
reason. Nutrition can only be made a science by limiting the articles of
food to such things as will reproduce all the chemical elements of the
human body, mentioned at the beginning of this lesson.
The further we remove foods from their natural state, the more difficult
becomes their analysis, their reliability, and a knowledge of their
chemistry, therefore the menus that appear in this work include only the
foods that will give to the body the best elements of nutrition.
[Sidenote: Prepared foods unscientific]
There is but little difficulty in ascertaining the chemistry of natural
foods, but when they have been preserved, pickled, canned, smoked,
evaporated, milled, roasted, toasted, oiled, boiled, baked, mixed,
flavored, sweetened, salted, soured and put into the popular commercial
forms, it becomes very difficult, if not impossible, to know what we are
eating, or to estimate the results.
Man is the net product of what he eats and drinks. Food bears very much
the same relation to him that soil does to vegetation. The following
questions, therefore, should be solved by every one who believes that
success and happiness depend upon health and vitality:
1 How to select and how to combine foods which will give to
the body a natural result, which is _health_
2 How to select and how to combine foods so that they will
counteract and remove the causes of dis-ease
3 How to select foods which contain all the chemical elements
of the body, and how to combine and proportion them at each meal so
that they will chemically harmonize
4 How to determine the quantity of food to be taken each day,
or at each meal, that will give to the body all the nourishment it
is capable of assimilating
_Note_: Too much food, even of the right kind, defeats this purpose and
produces just the opposite result.
* * * * *
Upon this knowledge hinges the building of a natural body, the cure of
a vast majority of dis-eases, our ability to reach the highest state of
physical and mental vitality, the prolongation of youth and longevity.
OUR FOOD MUST FIT INTO OUR CIVILIZATION
_We must make our diet fit into our civilized requirements._
Civilization has imposed many customs, habits, and duties upon us that
have not been properly met by nutrition or diet. This is why nearly 91
per cent of our ills are caused by errors in eating.
[Sidenote: Effect of sedative occupations upon nutrition]
Under continued physical exertion, the body will thrive for a time on
an unbalanced diet. It will cast off surplus nutrition, and convert one
element into another, a problem unknown to modern science, but under
sedative or modern business habits and occupations, it will not continue
to cast off a surplus, or to reconvert nutritive elements. As a result
of an unbalanced bill of fare, the nutrients taken in excess of the
daily needs undergo a form of decomposition, producing what is called
autointoxication, and become a most prolific source of dis-ease.
WHY THE SCIENCE OF HUMAN NUTRITION IS IN ITS INFANCY
The reader may inquire why it is that all other branches of science have
advanced so rapidly, and the science of human nutrition has just begun.
The reasons are:
1 Our ancestors, for many thousand years, were taught that
dis-ease was a visitation of Divine Providence, therefore to combat
it was to tempt the Almighty.
2 Doctors of medicine who have been custodians of the people's
health for many centuries have seldom been food scientists. Most of
them attempt to combat disease with drugs.
Now we are beginning to learn the truth about the origin of disease and
in considering the body as a human engine, to take into consideration
the all-important question of fuel.
[Sidenote: Tendency of the modern physician toward food science]
That the most learned physicians are drifting more and more toward
scientific feeding and natural remedies is a matter of common knowledge.
This splendid army of laborers in the great field of human suffering is
made up largely of what is termed the _Modern Doctor_--the man who is
brave enough to think and to act according to his better judgment.
Just to the extent that we understand the origin of drugs, and the
drugging system of treating dis-ease, we turn instinctively _from them_,
and instinctively _toward_ food, for in drugs we find an ancient system
of guesswork, while in food we find fundamental principles and primary
causes. The majority of causes are removed when the diet is made to fit
our physical condition and environment, and we then become normal by
the process of animal evolution, Nature merely bestowing upon us our
birthright because we have obeyed her laws.
3 The true science of human nutrition can be evolved only from
an accurate knowledge of both food chemistry and of physiological
chemistry.
[Sidenote: Why food chemistry and physiological chemistry have not been
united]
The science of physiological chemistry has been known and taught for
more than one hundred years, while the science of food chemistry is
of recent origin. These two branches have been kept separate because
they grew up at different periods of time. United they constitute the
greatest science known to mankind, because they affect his health, his
happiness, his life, and above all they measure the period of time he
will live.
Physiological chemistry tells what the body is and its needs--food
chemistry tells how to supply these needs. Recognizing these facts, I
have merely united these hitherto unapplied branches of science, and
have made of the union the science of Applied Food Chemistry, which
makes practical that which has heretofore been confined mainly to
theory.
LESSON II
SIMPLE PRINCIPLES OF GENERAL CHEMISTRY
[Sidenote: Relation of chemistry to food science]
If the student is versed in chemistry, this lesson will serve merely
as a review; if not, somewhat close attention must be given to facts
which at first may seem uninteresting. Patience should be exercised,
for, while all the information herein given does not, taken as a whole,
bear directly upon the subjects of health and dis-ease, yet with this
knowledge it will be much less difficult to understand the principles
which are applied later when we take up the chemistry of the body and
the chemistry of food.
Chemistry is not, as popularly supposed, a science far removed from
everyday life. Everyone has some knowledge of chemistry, but the
chemist has observed things more minutely and therefore more accurately
understands the composition of substances and the changes that are
everywhere taking place. For illustration:
A cook starts a fire in a stove. She knows that the fire
must have "air" or it will not burn; that when the fire is first
lighted, it "smokes" heavily, but as it burns more, it smokes less;
further, that if the damper in the pipe is closed the "gas" will
escape in to the room.
[Sidenote: Fire, gas, and smoke the result of chemical changes]
The chemist also knows this, but because he has compared his
observations with similar events elsewhere, he is enabled to express
his knowledge in the language of science. To the chemist, fire is the
process of combustion--the union of the oxygen of the air with the
carbon and hydrogen compounds of the wood or of the coal. The heat of
the fire is generated by this chemical union. To the chemist, the
smoke is a natural phenomenon occasioned by particles of carbon which
fail to unite with the oxygen gas. The gas, which to the woman suggests
suffocation if enough of it escapes into the room, to the chemist
suggests a compound resulting from combination of the oxygen with the
carbon.
CHEMICAL ELEMENTS
To the chemist, all forms of matter are mere combinations of elements.
Chemical analysis is a process of separating, dividing, and subdividing
matter. When the chemist separates or analyzes compounds, until he can
no longer simplify or subdivide them, he calls these simple products
"chemical elements."
[Sidenote: Common elements]
Many of the chemical elements are well known, such as copper, iron, and
gold. Other elements that are still more common are unknown in their
elementary form, because they combine with other elements so readily
that they exist in nature only as compounds. For example: Hydrogen,
united with oxygen, forms water; the elements chlorin and sodium,
combined or united, form common salt.
[Sidenote: Number of elements]
Altogether chemists have discovered about eighty-four elements, many of
which are rare, and do not occur in common substances.
All substances of the earth, whether dead or living, are formed of
chemical elements. These elements may be found in the pure or elementary
state, or they may be mixed with other substances, or they may be
combined chemically. Copper, iron, and gold are elements in the pure
state. If we should take iron and copper filings and mix them together,
we would still have copper and iron. Were we to take copper and gold and
melt them together, we would have a metal that would be neither copper
nor gold. It would be harder than one and softer than the other. But
this substance would still be a mixture, and its properties half way
between copper and gold.
[Sidenote: Examples of chemical changes]
If a piece of iron be exposed to dampness it will soon become covered
with a reddish powder called "rust." The rusting of iron is a process of
chemical changes in which the original substance was wholly changed by
chemically uniting with the oxygen and the moisture of the atmosphere,
which is really a process of combustion. The burning of wood, the
rusting of iron, the souring of milk, and the digestion of food are, in
a way, all mere examples of chemical changes.
[Sidenote: Difference between chemical compounds and simple mixtures]
Care should be exercised to distinguish chemical compounds from simple
mixtures. Air is not a compound, but a mixture of oxygen, hydrogen and
nitrogen gases. Water, however, is a compound of oxygen and hydrogen.
Both salt and sugar are compounds, but if we grind them together,
we do not have a new compound, but a mixture of two compounds. Most
of the common things around us are mixtures of different compounds
or substances. Rocks are mixtures of many different compounds. Wood
is, likewise, formed of many different substances. Wheat contains
water, starch, cellulose, and many other compounds. Grinding the wheat
into flour does not change it chemically, but if we heat the flour
in an oven, some of the starch is changed into dextrin. The starch
has disappeared, and dextrin, a new substance, appears in its place.
Whenever elements are combined into compounds, or compounds broken up
into elements, or changed into other compounds, we have true chemical
action.
[Sidenote: Names of elements--how derived]
The names of the elements are formed in many different ways. The name
chlorin is derived from a Greek word meaning _greenish-yellow_, as
this is the color of chlorin. Bromin comes from a Greek word meaning
_a stench_, a prominent characteristic of bromin being its bad odor.
Hydrogen is formed from two Greek words, one of which means _water_ and
the other to _produce_, signifying that it enters into the composition
of water. Potassium is an element found in potash, and sodium in soda,
etc.
[Sidenote: Symbols of elements--how derived]
For convenience, abbreviations are used for the names of elements
and compounds. Thus, instead of oxygen, we may write simply "O"; for
hydrogen, "H"; for nitrogen, "N," etc. Very frequently the first letter
of the name of the element is used as the symbol. If the names of two or
more elements begin with the same letter, some other letter of the name
is added. In some cases the symbols are derived from the Latin names of
the elements. Thus, the symbol of iron is Fe, from _ferrum_; of copper,
Cu, from _cuprum_.
The following table gives the names of the elements which it will be
necessary to understand in pursuing this work.
Aluminum Al
Arsenic As
Boron B
Bromin Br
Calcium Ca
Carbon C
Chlorin Cl
Chromium Cr
Copper Cu
Fluorin F
Gold Au
Hydrogen H
Iodin I
Iron Fe
Lead Pb
Magnesium Mg
Mercury Hg
Nickel Ni
Nitrogen N
Oxygen O
Phosphorus P
Platinum Pt
Potassium K
Silicon Si
Silver Ag
Sodium Na
Sulfur S
Tin Sn
Zinc Zn
AIR AND OXYGEN
[Sidenote: Composition of air]
AIR--The air consists chiefly of two substances, only one of which can
keep up the process of burning. This substance is known as oxygen. The
other, in which nothing can burn, is known as nitrogen. Besides these
the air contains smaller quantities of other substances, particularly
water vapor, carbonic acid (carbon dioxid), ammonia, and carburetted
hydrogen.
[Sidenote: Distribution of oxygen]
OXYGEN--Oxygen is the most common element in nature. It forms between
forty and fifty per cent of the solid crust of the earth, eight-ninths
of all the water on the globe, and one-fifth of all the air around the
globe.
We have oxygen around us in great abundance, but it is mixed with
nitrogen, and it is difficult to separate the two so as to secure the
oxygen for any practical or commercial use.
MANUFACTURE OF OXYGEN
There are three methods of obtaining oxygen:
1 From _potassium chlorate_, or, as it is commonly called,
chlorate of potash.
When potassium chlorate (KCLO₃) is heated in a closed vessel
(closed vessel means "closed at one end"), it breaks up into
potassium chlorid and oxygen; that is, KCLO₃ + heat = KCL + O₃.
Potassium chlorate is used in fireworks because it gives up
its oxygen readily. Potassium nitrate serves the same purpose in
gunpowder, which is a mixture of sulfur (S), charcoal (C), and
salt-peter or potassium nitrate (KNO₃). The explosion of gunpowder,
after a certain temperature has been reached, is due to the
formation of oxygen, which, combined with the potassium nitrate, is
set free by the very rapid burning of the charcoal and the sulfur.
Other gases formed by the explosion are nitrogen, and probably
sulfur dioxid (SO₂), and oxids of nitrogen, N₂O, NO₂, etc. Carbon
monoxid and carbon dioxid are sometimes formed. Potassium nitrate,
however, is the most active agent in gunpowder.
2 By the _electrolysis of water_.
By this method the oxygen and the hydrogen are separated by
electricity.
3 By the _liquefaction of air_, which is a very recent and a
very scientific method.
By this method the air is cooled down until it liquefies.
At normal atmospheric pressure it liquefies at a temperature of
--312.6°F., but under pressure of about 585 pounds it liquefies
at a temperature of --220°F. After the air has been liquefied, it
is allowed to go back to vapor by exposing it to the surrounding
heat of the atmosphere, and this vaporization separates the
nitrogen from the oxygen, as the nitrogen boils at a temperature of
--318°F., while the oxygen boils at a temperature of --294°F. There
is a difference of about 24° in the boiling points of these two
gases, which at this low point amounts to more than the difference
between the boiling points of alcohol and water, and this
difference is sufficient to separate the oxygen from the nitrogen.
Production of oxygen by the liquefaction of air is the latest,
cheapest, and most approved method, and is now becoming extensively
used in obtaining both oxygen and nitrogen for commercial use.
[Sidenote: Properties of oxygen]
Oxygen is tasteless and odorless. It is slightly heavier than air. When
subjected to an extremely high pressure and low temperature it becomes
liquid.
CHEMICAL ACTION OF OXYGEN
(a) _Upon Substances_
[Sidenote: Effect of air upon iron and wood]
Upon some substances oxygen acts at ordinary temperature. Iron becomes
covered with rust when exposed to air and moisture. Wood and other
vegetable and animal substances undergo slow decomposition when exposed
to the air. This is partly due to the action of oxygen at ordinary
temperature.
[Sidenote: Pure oxygen aids combustion]
A splinter of wood will burn brilliantly in a jar of pure oxygen, and
much more rapidly than in common air. Pure oxygen gas will cause many
substances to burn which will not burn in air. Iron can be burned in
pure oxygen, leaving only a reddish powder.
[Sidenote: Formation of iron-rust]
When iron rusts the carbon dioxid and water vapor combine chemically
with the iron, and form what is known as a basic hydroxid or carbonate
of iron. The process is somewhat complex. When iron burns in oxygen a
red powder is formed--ferric oxid, Fe₂O₃. Iron dissolves in water, or
moisture from the air containing carbonic acid, forming acid ferrous
carbonate--
Fe + 2H₂CO₃ = FeH₂(CO₃)₂ + H₂
Iron + Carbonic acid = Acid ferrous carbonate + Hydrogen
This acid ferrous carbonate, on drying or further oxidation, is
converted into _iron-rust_. If we represent _iron-rust_ by the formula
Fe₂O₃. 2Fe(OH)₃, the equation is as follows:
4FeH₂(CO₃)₂ + O₂ = Fe₂O₃. 2Fe(OH)₃ + H₂O + 8CO₂
Acid ferrous carbonate + Oxygen = Iron-rust + Water + Carbon dioxid
(b) _In Living Bodies_
The most interesting action of oxygen at ordinary temperature, however,
is that which takes place in our bodies and the bodies of all other
animals.
[Sidenote: Rate of blood circulation]
[Sidenote: Oxidation of waste matter]
By the constant action or beating of the heart all the blood in the body
is brought to the lungs every two or three minutes. The actual time
has not been determined in man. In large arteries the blood flows ten
times as fast as in very small ones. The usual time through a capillary
is one second. The time has been determined, however, in lower animals.
In a horse the blood travels one foot a second in the largest artery.
At present the accepted theory is that in the circuit the blood makes
throughout the body, it picks up the waste matter from tissue that has
been torn down by work or effort, and brings it to the lungs, where it
meets with the oxygen we breathe and is oxidized or burned.
If the body undergoes excessive effort or exercise, it tears down
an excessive amount of tissue, and there is created, therefore, an
excessive amount of waste or carbon dioxid. Nature very wisely provides
for this contingency by increasing the heart action, thereby sending
the blood through the body at greater velocity, forcing more blood to
the lungs, thus increasing the demand for oxygen, which is expressed by
deep and rapid breathing.
[Sidenote: Generation of heat and light]
When a substance burns it gives off heat, and generally light. The heat
is the result of chemical change or combination, and the light is the
result of heat. Whenever oxidation takes place, no matter in what form,
heat is produced.
[Sidenote: Amount of heat determined by amount of oxygen]
The amount of heat given off by the combination of a given amount of
oxygen with some other substance is always the same. If it takes place
at a very high temperature, as in explosives, the heat is all given off
at once, but if it takes place more slowly, the heat passes away, and we
may not observe it, but careful experiments prove that heat is always
present in oxidation, and the amount of heat is always measured by the
amount of oxygen.
[Sidenote: Law governing oxidation of given quantity of food]
That the combination of oxygen with other substances always produces a
certain amount of heat is a very important fact to the food scientist,
as this law enables him to determine in the laboratory the exact amount
of heat that is produced in the oxidation of a pound, or of any given
quantity of food; this food will also produce exactly the same amount of
heat if oxidized in the human body.
[Sidenote: Heat and motion]
We know that by means of heat we can produce motion. The steam-engine
is the best example of this law. We build a fire under the boiler; the
oxygen of the air unites with the carbon in the coal; the combustion
converts the water into steam; the steam is conveyed to a cylinder; the
pressure pushes a piston; the motion of the piston causes motion in the
engine, and the train or ship moves.
[Sidenote: Determination of body-heat and energy]
From such facts we know that not only the amount of heat, but the amount
of work or energy that food or fuel will yield can be determined with
reasonable accuracy. Many conditions obtain in the body, however, that
do not occur in the laboratory, hence we must study these conditions
before we can fully understand the natural laws that govern the
production of heat, and energy or work, by oxidation in the living body.
HYDROGEN AND WATER
[Sidenote: Distribution and production of hydrogen]
HYDROGEN--Hydrogen is found in nature very widely distributed and
in large quantities. It forms one-ninth of the weight of water, and
is contained in all the principal substances which enter into the
composition of plants and animals. It may be obtained by decomposition
of water by means of the electric current, or by the action of
substances known as acids on metals. The latter method is more commonly
used in the laboratory. Acids contain hydrogen, give it off easily, and
take up other elements in its place. Among the common acids found in
every laboratory are hydrochloric, sulfuric, and nitric.
[Sidenote: Physical properties of hydrogen]
Pure hydrogen is a colorless, odorless, tasteless gas. It is not
poisonous, and may therefore be inhaled without harm. It is the lightest
known substance, being about 14.4 times lighter than air, 16 times
lighter than oxygen, and 11,000 times lighter than water.
[Sidenote: Chemical properties of hydrogen]
Hydrogen does not unite with oxygen at ordinary temperatures, but,
like wood and most other fuel substances, needs to be heated up to the
kindling temperature before it will burn. Hydrogen burns if a lighted
match be applied to it. The flame is colorless, or very slightly blue.
[Sidenote: Decomposition of water]
WATER--Water is a compound and not an element, as can be shown by
passing an electric current through it. If the ends of two wires, each
connected with an electric battery, be put a short distance apart, in
acidulated water, it will be noticed that bubbles of gas rise from each
wire. As these gases cannot come from, or through the wires, they must
be formed from the water. If they be analyzed, we will find that oxygen
gas comes from one wire and hydrogen from the other.
[Sidenote: Proportion of hydrogen and oxygen in water]
This experiment shows that when an electric current is passed through
water, hydrogen and oxygen are obtained, and also that there is obtained
twice as much hydrogen as oxygen by volume. This proves that water is
not an element, but a compound of two atoms of hydrogen and one of
oxygen. The chemist therefore writes the symbol for water H₂O.
We have just learned that with electricity we could decompose the
compound water into its elements, hydrogen and oxygen. Now we can
prove by another experiment that water contains these two elements. If
we burn hydrogen gas, or any substance containing hydrogen, water is
formed. This can be illustrated by inverting a cool, dry tumbler over a
gas flame, which is composed chiefly of hydrogen, and water vapor will
collect on the inside.
[Sidenote: Properties of water]
Though water is widely distributed over the earth, we never find it
absolutely pure in nature. All natural waters contain foreign substances
in solution. These substances are taken up from the air, or from the
earth. Pure water is colorless, tasteless, and odorless.
[Sidenote: Why ice floats]
On cooling, water contracts until it reaches the temperature of 4°
Centigrade (39° Fahrenheit). When cooled from 4° to 0° C. it expands,
and the specific gravity, or weight compared with the space occupied by
ice, is somewhat less than that of water; hence ice floats.
[Sidenote: Rain-water]
[Sidenote: Hard water]
[Sidenote: Mineral water]
The purest water found in nature is rain-water, particularly that which
falls after it has rained for some time; that which first falls always
contains impurities from the air. As soon as rain-water comes in contact
with the earth and begins its course toward the sea, it also begins to
take up various substances according to the character of the soil with
which it comes in contact. Mountain streams which flow over rocky beds,
particularly beds of sandstone, contain very pure water. Streams which
flow over limestone dissolve some of the stone, and the water becomes
"hard." The many varieties of mineral water from the various springs
throughout the country, take their properties from soluble substances
with which they come in contact.
[Sidenote: Salt water]
Common salt is deposited in large quantities in different parts of the
earth. Since salt is readily soluble in water, many streams pick up
large quantities of it, and as all water courses ultimately find their
way to the ocean, the latter becomes a repository for salt with which
the earth-water is laden.
[Sidenote: Effervescent waters]
Effervescent waters all contain some gas, usually carbonic acid gas in
solution, and they merely give up or set free a part of it when placed
in open vessels.
[Sidenote: Sulfur water]
Sulfur water contains a compound of hydrogen and sulfur, called hydrogen
sulfid or sulfureted hydrogen, which we will refer to in its order later
in this lesson.
[Sidenote: Distilled water]
Water may be purified by means of distillation. This consists in boiling
the water and condensing the vapor by passing it through a tube which is
kept cool by surrounding it with cold water. By means of distillation
most substances in solution in water can be eliminated. Substances,
however, which evaporate like water, will, of course, pass off with the
water vapor. Aboard ship salt water is distilled and thus made fit for
drinking. In chemical laboratories ordinary water is distilled in order
to purify it for chemical work.
USES OF WATER IN CHEMISTRY
[Sidenote: Action of water in physiological chemistry]
Water is termed by the chemist a stable compound. This means that it is
difficult to get it to act chemically. Being thus inactive chemically,
we find that water does not combine with most substances. There are
exceptions to this, however, especially in physiological chemistry, an
instance being that starch combines with water when it is changed to
sugar in the process of digestion.
[Sidenote: Water as a solvent]
Water is the universal solvent. A greater number of substances dissolve
in it than in any other liquid. Chemical operations are frequently
carried on in solution, that is to say, the substances which are to act
chemically upon each other are first dissolved in water. The object of
this is to get the substances into as close contact as possible. If
we rub two solids together, the particles remain slightly separated,
no matter how finely the mixture may be powdered. If, however, the
substances are dissolved and the solutions poured together, the
particles of the liquid move so freely among each other that they come
in direct contact, thus aiding chemical action. In some cases substances
which do not act on each other at all when brought together in dry
condition, act readily when brought together in solution.
There is a limit to the amount of any substance which can be held in
solution at a given temperature.
[Sidenote: Chemical meaning of solution]
The question will probably arise in the mind of the student as to
whether a substance dissolved in water has chemically united with the
water, or is merely mixed. Solution is in reality a process about half
way between mixing dry substances and forming chemical combinations.
The chemist considers that the water does not form a compound with the
substance dissolved, when he can, by evaporating the water, get the
substance back into its original form.
IMPORTANCE OF SOLUTION TO THE FOOD SCIENTIST
[Sidenote: Relation of solution to assimilation]
Solution is very important in the study of foods and human nutrition.
Only substances which can be dissolved can be assimilated. Many
substances which will not dissolve in pure water will dissolve in water
which contains something else in solution. The blood is water containing
many things in solution. The salts of the blood keep the other food
elements in solution, many of which would not dissolve if the blood
did not contain these salts. The chief work of the digestive juices
is to reduce foods to a soluble form so that they can be taken into
the circulation by absorption; otherwise they would pass through the
alimentary canal practically unchanged.
[Sidenote: Milk as an example of both "Solution" and "Mixture"]
We must learn to distinguish carefully between chemical solution and
merely mixing things with water. A good example is milk. In addition to
water, milk contains principally fat, sugar, and casein. The sugar is
truly dissolved in the water. The fat and the casein are fine particles
held in suspension. If the milk stands for a while, the fat particles
rise to the top as cream. If it stands long enough, the casein particles
adhere to each other and settle to the bottom, leaving the water with
the dissolved sugar or whey in the middle.
IMPORTANCE OF WATER IN THE HUMAN BODY
[Sidenote: Proportion of water and solids in the human body]
Water, which forms about sixty-six per cent of the human body, is by far
the most important substance therein. It comprises the major part of the
blood serum and every tissue and organ. If a normal human body weighing
150 pounds were put into an oven and thoroughly dried, there would be
left only about 50 pounds of solid matter, all the rest being water.
The proportion of water in animal and vegetable substances is also very
great. As water is also a conspicuous factor in all foods, either in
chemical combination, or in solution with other elements mechanically
mixed, it is obvious that water is an important factor in food science.
USES OF WATER IN THE BODY
The uses of water in the body may be roughly grouped into three
divisions, as follows:
1 Water in small quantities enters into the actual chemical
composition of the body.
As we will notice in the discussion of carbohydrates, water
combines chemically with cane-sugar when it is digested and
transformed into glucose. (See Lesson IV, "Cane-sugar," page 112.)
2 Water forms a portion of the tissues and acts as a solvent
in the body-fluids.
[Sidenote: What blood carries in solution]
In this function the water is not changed chemically, but is
only mixed with other substances; thus the blood is in reality
water with glucose, peptone, etc., in solution, and carrying along
with them red blood-corpuscles and fatty globules.
3 Water is a most important factor in the digestion, and the
assimilation of food, and the elimination of waste.
[Sidenote: Drinking with meals]
Inasmuch as the body is nearly two-thirds water, it follows
that the diet should be composed of about 66 per cent moisture.
The old theory of dietitians that no water should be taken with
meals was based upon the hypothesis that the water diluted the
gastric juice, and that this diluted form of the gastric juice
weakened its digestive power. Actual practise has proved this
thesis to be untrue. Water is the great universal solvent, and the
hydrochloric acid of the stomach is only a helper, as it were, in
the dissolution or the preparation of food for digestion.
Water is also a valuable agent in the elimination of
body-poisons.
[Sidenote: Value of water to blood]
The liberal use of water keeps the blood supplied with the
necessary moisture, and that excess which is eliminated through the
kidneys carries away poisons that would reside in the body very
much to the detriment of health. There is little danger, therefore,
in drinking too much pure water, but much care should be exercised
that it be pure, or at least free from lime and mineral deposits.
The best water is pure water, free from all mineral substances.
[Sidenote: When water drinking is unnecessary]
[Sidenote: Disorders caused by insufficient moisture]
If a meal consists of watery food, such as fresh vegetables, salads,
etc., then the drinking of water becomes unnecessary; but where the
meal is composed chiefly of solids, then an amount of water should be
taken sufficient to make up 66 per cent of the total. If more water
is taken than is necessary for this purpose, the excess will pass off
and the stomach will only retain the necessary amount; but if the
quantity of moisture is insufficient, the stomach calls to its aid an
excess of hydrochloric acid, the strength of which has a tendency to
crystallize the starch atom (especially cereal starch), thereby causing
the blood-crystal, which is one of the primary causes of rheumatism,
gout, lumbago, arterial sclerosis (hardening of the arteries), and all
disorders caused by congestion throughout the capillary and the arterial
systems. The most common disorder among civilized people is hydrochloric
acid fermentation. Copious water drinking at meals is the logical remedy
for this disorder.
The proper amount of pure non-mineral water taken with food will do much
to remove the causes of superacidity and the long train of ills that
follow this disorder. (See "Chart," Lesson I, page 9.)
In this work I shall constantly refer to these various uses of water,
especially as a solvent (an aid to digestion), and as a remedial and
curative agent.
[Sidenote: Man's source of water]
Theories have been promulgated by hygienic teachers in the past few
years that man should get his supply of water wholly from the juices of
fruits, and not drink ground-waters, which are contaminated with mineral
substances. While it may be true that water in certain localities, such
as in the alkali deserts, is unfit for drinking, yet the writer believes
that the promulgators of the theory that man is not a drinking animal
never did a hard day's work in a harvest field. In the dry winds of the
western plains water evaporates from the surface of the body at the
rate of twelve or fifteen pounds a day. The theory of deriving one's
water supply wholly from fruits would not stand the test of such facts.
NITROGEN AND NITROGEN COMPOUNDS
[Sidenote: Sources of nitrogen]
We have learned that the air is composed chiefly of oxygen and nitrogen.
These are not combined as oxygen and hydrogen are in water, but are
simply mixed together, four-fifths of the mixture being nitrogen.
Nitrogen is also found in combination in a large number of substances in
nature. It is found in the nitrates, as salt-peter or potassium nitrate,
KNO₃, and Chili salt-peter or sodium nitrate, NaNO₃. It is also found in
the form of ammonia, which is a compound of nitrogen and hydrogen of the
formula NH₃, and exists in that form in a limited quantity of the air.
In most foods, especially in those of animal origin, nitrogen occurs in
chemical combination.
[Sidenote: Properties of nitrogen]
Nitrogen is a colorless, tasteless, odorless gas which does not burn,
and does not combine readily with oxygen, or with any other element
except at a very high temperature, and except in the formation of living
plants, or in animal life. Just as nitrogen does not support combustion,
so also it does not support life. An animal would die confined in a tank
of nitrogen, not on account of any active poisonous properties in the
nitrogen, but for lack of oxygen.
[Sidenote: Compounds of nitrogen]
When a compound containing carbon, hydrogen and nitrogen is heated in
a closed vessel, so that the air is excluded, and so that it cannot
burn, the nitrogen passes out of the compound, not as nitrogen, but
in combination with hydrogen, which forms ammonia. Nearly all animal
substances contain carbon, hydrogen, oxygen, and nitrogen, and many of
them give off ammonia when heated as above described.
[Sidenote: Why ammonia is used in making artificial ice]
Ammonia is written by the chemist NH₃, or one part of nitrogen gas to
three parts of hydrogen. It is a colorless, transparent gas with a
very penetrating, characteristic odor. In concentrated form it causes
suffocation. It is but little more than half as heavy as air. It is
easily converted into liquid form by pressure and cold. When pressure
is removed from the liquefied ammonia, it passes back very rapidly
into gaseous form, and in so doing it absorbs heat. Investigators have
taken advantage of these facts and are employing liquid ammonia in the
manufacture of artificial ice.
[Sidenote: Importance of proportioning food]
While air is merely a mixture of oxygen and nitrogen, this does not
prove that these two elements cannot unite. In fact they do unite in
five different proportions so as to form five different substances.
These are given below to illustrate how different substances can be
formed from the same things, by merely combining them in different
proportions. This example is also given to impress upon the mind of the
practitioner the great importance of proportioning nutritive elements
in diet so that the patient will not be overfed on some elements while
underfed on others. It is absolutely essential, in order to know what
effect a substance will have in the laboratory, or in the body, to know
not only of what it is composed, but with what substances and in what
proportions it is combined.
Nitrous oxid .....N₂O
Nitric oxid ......NO or N₂O₂
Nitrogen trioxid .. N₂O₃
Nitrogen peroxid.. NO₂ or N₂O₄
Nitrogen pentoxid N₂O₅
To further illustrate the wonders of chemical combinations, we give the
properties of two of these oxygen and nitrogen compounds:
[Sidenote: Properties and uses of nitrous oxid]
Nitrous oxid, N₂O, is colorless, transparent, and has a slightly
sweetish taste. When inhaled it causes a kind of intoxication which
manifests itself in the form of hysterical laughing, hence it is
commonly called "laughing gas." Inhaled in larger quantities it causes
unconsciousness and insensibility to pain. It is, therefore, used in
many surgical operations, particularly by dentists in extracting teeth.
Nitrogen peroxid, NO₂, is a reddish-brown gas. It has an extremely
disagreeable odor and is very poisonous.
[Sidenote: Composition of nitric acid]
[Sidenote: Properties of nitric acid]
By oxidation the nitrogen of animal substances is converted into nitric
acid, HNO₃. Furthermore, the silent, continuous action of minute living
organisms in the cell is always tending to transform the waste-products
of animal life into compounds closely related to nitric acid. This
acid, as its chemical formula indicates, is formed by the combination
of the three elements we have just studied, namely, hydrogen, nitrogen,
and oxygen. Pure nitric acid is a colorless liquid. It gives off
colorless, irritating fumes, when exposed to the air. Strong nitric acid
acts violently upon many substances, particularly those of animal and
vegetable origin, decomposing them very rapidly. Nitric acid burns the
flesh, eats through clothing, disintegrates wood, and dissolves metals.
It is one of the most active of chemical substances.
The compounds of nitrogen that occur in food are very numerous and of
complex composition. They will be discussed in Lessons III and IV, pages
99 and 125 respectively.
CHLORIN
[Sidenote: Sources of chlorin]
Chlorin, though widely distributed in nature, does not occur in very
large quantities as compared with oxygen and hydrogen. It is found
chiefly in combination with the element sodium, as common salt or sodium
chlorid, which is represented by the symbol NaCl.
[Sidenote: Properties of chlorin]
Chlorin is a greenish-yellow gas. It has a disagreeable smell and
acts upon the passages of the throat and nose, causing irritation and
inflammation. The feeling produced is much like that of a cold in the
head. Inhaled in concentrated form, that is, not diluted with a great
deal of air, it would cause death. It is much heavier than air, combines
readily with other substances, and possesses the property of bleaching
or destroying colors.
HYDROCHLORIC ACID
[Sidenote: Hydrogen and chlorin combined]
Just as hydrogen burns in the air, so it burns in chlorin. The burning
of hydrogen in air or oxygen is, as we have seen, simply the combination
of hydrogen and oxygen, the product being water in the form of vapor,
and therefore invisible. When hydrogen burns in chlorin, the action
consists in the union of the two gases, the product being hydrochloric
acid, HCl, which forms clouds in the air. The two gases, hydrogen
and chlorin, may be mixed together and allowed to stand together
indefinitely in the dark, and no action will take place. If, however,
the mixture be put into a room lighted by the sun, but where the sun
does not shine directly upon it, combination takes place gradually;
but if the sun be allowed to shine directly upon the mixture for an
instant, explosion occurs, this being the result of the combination of
the two gases. The same result can be caused by applying a flame or
spark to the mixture. In this case light causes chemical action. The art
of photography depends upon the fact that light has the power to cause
chemical changes.
[Sidenote: Importance and preparation of hydrochloric acid]
I will here consider hydrochloric acid somewhat in detail, because it
is very important in the digestion of food, being the principal fluid
composing the gastric juice of the stomach. Hydrochloric acid is always
made by treating common salt (one afflicted with acid fermentation
should omit the use of salt and soda), under high temperature, with
sulfuric acid. This product is given off as a gas, which dissolved in
water forms hydrochloric acid, sodium sulfate remaining behind as a
result of this process. The chemist describes the action that takes
place by writing what is called a chemical equation, as follows:
2NaCl + H₂SO₄ = Na₂SO₄ + 2HCl
Sodium chlorid + Sulphuric = Sodium + Hydrochloric
(common salt) acid Sulfate acid
The reader will observe that there are as many parts of each element on
the right as on the left-hand side of the = mark. Two parts of common
salt yield two parts each of sodium (Na) and chlorin (Cl). The sodium
appears as _Na_ in the sodium sulfate, and the chlorin as _Cl_ in the
two parts of hydrochloric acid.
This method of expressing chemical action by these equations may be
somewhat confusing at first to those who have not studied chemistry, but
it is best to have all such become familiar with them that they may have
the further benefit of understanding the general terms of chemistry.
Hydrochloric acid gives up its hydrogen when brought into contact with
certain metals like iron, zinc, etc., and takes up these metallic
elements in place of the hydrogen. Thus zinc and hydrochloric acid give
zinc chlorid and hydrogen.
Zn + 2HCL = ZnCl₂ + H₂
Zinc + Hydrochloric acid = Zinc chlorid + Hydrogen
ACIDS, BASES, NEUTRALIZATION, SALTS
[Sidenote: Relation of acids to bases]
We have already discussed a number of substances called acids. It is
necessary to inquire why chemists call them acids. What is there in
common, for example, between the heavy, oily liquid sulfuric acid and
the colorless gas, hydrochloric acid? It is not possible to understand
the nature of their common properties without examining a class of
substances called alkalis or bases.
Acids and bases have the power to destroy the characteristic properties
of each other. When an acid is brought into contact with a base, in
proper proportions, the characteristic properties of both the acid and
the base are destroyed. They are said to neutralize each other.
[Sidenote: Common acids and bases and tests therefor]
The most common acids are sulfuric, hydrochloric, and nitric. Among
the more common bases are caustic soda, caustic potash, and lime. A
convenient way to recognize whether a substance has acid or basic
properties is by means of certain color-changes. Litmus is a coloring
matter which is ordinarily blue. If a solution which is colored blue
with litmus be treated with a drop or two of an acid, the color is
changed to red. If the red solution be treated with a few drops of a
solution of a base, the blue color is restored.
Many substances change in color according to whether the solutions in
which they are present are acid or alkaline. An infusion of red cabbage,
for example, changes color when treated with an acid, and recovers its
color when again treated with an alkali.
[Sidenote: Formation of common salt]
What happens in the chemical sense in this neutralizing process is
nicely illustrated by the formation of common salt from hydrochloric
acid and caustic soda, also called sodium hydroxid. When these two
substances are dissolved in water, and the solutions mixed, the chemical
action is as follows:
HCL + NaOH = H₂O + NaCl
Hydrochloric acid + Caustic soda = Water + Common salt
(Muriatic acid) (Sodium hydroxid) (Sodium chloride)
[Sidenote: Common examples of neutralization]
The strong hydrochloric acid with its pungent odor and sour taste, and
the caustic alkali with its equally characteristic properties have both
disappeared, and in their place we find nothing more wonderful than
common salt dissolved in water. Other forms of neutralization that are
very common are vinegar (acetic acid C₂H₄O₂) and soda, or sour milk
(lactic acid C₃H₆O₃) and soda. When bread is "sour," we mean that there
was not enough soda to neutralize the acid.
PRINCIPLES OF NEUTRALIZING ALKALIS
If we should try many experiments of neutralizing alkalis with acids, we
would discover these general rules:
1 All acids contain hydrogen.
2 All alkalis contain oxygen and hydrogen in equal proportions.
3 When these substances react, the hydrogen of the acid joins
the hydrogen of the base or alkali, forming water, H₂O.
4 The metal of the base always replaces the hydrogen of the
acid.
2KOH + H₂SO₄ = K₂SO₄ + 2H₂O
Potassium hydroxid + Sulfuric acid = Potassium Sulfate + Water
(alkali or base) (acid) (Salt)
(In the above equation the potassium (K) of the potassium
hydroxid replaces the Hydrogen (H) in the sulfuric acid.)
5 The other elements of the original compounds unite to form
a new substance, which is neither acid nor alkali, but which is
termed a salt.
The names of a few common acids, bases and salts, and their chemical
formulas, are given here, as many of them will be important in the
pursuance of this work.
ACIDS
HCl ........Hydrochloric (in gastric juice)
HNO₃ .......Nitric
H₂SO₄ ......Sulfuric
C₂H₄O₂ .....Acetic (vinegar)
C₆H₈O₇ .....Citric (lemon juice)
BASES
NaOH ......Sodium hydroxid (caustic soda)
KOH .......Potassium hydroxid (caustic potash)
Ca(OH)₂ ...Calcium hydroxid (slaked lime)
NH₄OH .....Ammonium hydroxid
(Ammonia gas dissolved in water produces this
alkali.) The equation for this is as follows:
NH₃ + H₂O + NH₄OH
(Ammonia) gas + Water + Ammonium hydroxid
SALTS
NaCl .......Sodium chlorid (table salt)
KNO₃ .......Potassium nitrate (salt-peter)
CuSO₄ ......Copper sulfate (blue vitriol)
Ca₃(PO₄)₂ ..Calcium phosphate (normal)
(The mineral of bones)
[Sidenote: Formation of salts in the human body]
FLUORIN, BROMIN, IODIN--These three elements are in many respects like
chlorin. The first is a gas, the second a heavy, reddish-brown liquid
at ordinary temperature, and the third a dark, grayish crystalline
solid. These elements all form acids just as chlorin forms hydrochloric
acid. These acids produce salts, and these various salts exist in small
quantities in the human body.
MINERAL SULFUR--This element is of no particular importance or use to
the body, as it is insoluble and cannot be digested. The compounds of
sulfur, however, are numerous and important. Sulfuric acid, sometimes
called oil of vitriol, is one of the most active chemicals known, and
is especially destructive to living tissue, as it combines with the
water in the tissue so rapidly as to char or burn it.
When sulfur is burned in air it forms sulfur dioxid, SO₂, which is used
for the purpose of fumigation or destroying alleged dis-ease germs.
This SO₂ dissolved in water gives H₂SO₃, sulfurous acid. By oxidizing
this another part of oxygen is added, forming H₂SO₄. All three of these
compounds are poisonous and harmful.
HYDROGEN SULFID, H₂S, is a poisonous gas with a bad odor. It is formed
by the decay of certain food substances, such as eggs. Sometimes this
gas occurs in intestinal fermentation.
CARBON DISULFID, CS₂, is used extensively to kill insects. The salts
of sulfuric acid, or sulfates, are quite important, and many of them
are poisonous. Glauber's salt (sodium sulfate Na₂SO₄) and Epsom salts
(magnesium sulfate MgSO₄) are extensively used by the medical profession
as purgatives. These poisons cause the intestines to act violently in an
effort to throw out the offending substances.
VEGETABLE SULFUR IN THE HUMAN BODY--I have herein mentioned a number
of sulfur compounds which are foreign or harmful to animal life. In
wonderful contrast to this is the fact that sulfur is an essential
constituent of the human body, and in certain complex compounds with
nitrogen and other elements, forms the brain, nerves, and many other
body-tissues.
PHOSPHORUS--This element is useful in the manufacture of common matches
because it possesses the power to ignite by friction. The things of
interest to the food scientist, however, are the salts of phosphoric
acid. These enter largely into the bones, and to some extent into the
nerves and other organs of the body.
SILICON is the element which, combined with oxygen, forms the greatest
part of the rocks and the sand of the solid earth. It forms the shell of
certain sea-animals. In the human body it is found in the teeth and in
the bones in very small quantities.
METALS--Metals, when united with oxygen and hydrogen, form the bases of
nearly all the substances studied in this lesson. When these act with
acids they produce the salts. It is these salts of the metals that are
of most interest to us. The salts of common metals, such as copper, tin,
lead, and iron do not enter into the composition of the human body, and
many of these are decidedly poisonous, especially those of copper, lead,
mercury, and arsenic.
[Sidenote: Importance of metals to digestive juices]
The metals whose salts are found in the body are sodium, potassium,
calcium, and magnesium. These metals in their elementary state are
seldom seen outside a chemist's laboratory, but we can judge of their
importance when we remember that the digestive juices contain these
metals. The teeth and all bony substances are formed from these
compounds, and the ability of all body-fluids to carry food material
in solution depends upon a definite per cent of these metal salts. The
study of minerals, or of mineral salts contained in food, together with
their uses in the body, forms an important subdivision of food chemistry.
IRON--Iron is mentioned separately from other metals because it not only
yields salts that occur in small quantities in the body, but because,
like sulphur, it enters into the complex nitrogenous portions of the
body to form part of the living substance itself.
[Sidenote: Iron in patent medicines]
This organic iron, as it is sometimes called, occurs chiefly in the red
blood-corpuscles. The patent medicines which are exploited for the iron
they contain, are frauds so far as nourishing the body is concerned. The
popular deception is caused by the general belief that all compounds
containing the same elements are alike in their uses. One might as well
swallow iron filings as to endeavor to build red blood corpuscles out of
the mineral solution of iron.
LESSON III
ORGANIC CHEMISTRY
CARBON
In this lesson I will consider carbon and carbon compounds, which are
the bases of all foods and living matter. I will devote but little
attention to theories and technicalities, but will discuss the subject
from scientific and practical standpoints.
Wood, flesh, and other products of vegetable or of animal life blacken
when heated to a sufficiently high temperature. This blackening is
due to the presence of carbon. If such substances are heated with an
abundant supply of air, the carbon combines with oxygen and forms a
colorless gas; that is, the carbon burns.
[Sidenote: Sources of carbon]
The principal form in which carbon occurs in nature is in combination
with other elements. It occurs not only in all living things, but in
their fossil remains, as in coal. All products of plant life contain
carbon, hydrogen, and oxygen. Among the more common of these are
sugar, starch, wood, etc. Most products of animal life contain carbon,
hydrogen, oxygen, and nitrogen. Among these are albumin, fibrin, casein,
etc.
Carbon occurs in the atmosphere in the form of carbon dioxid or carbonic
acid gas. It is also found in the earth in the form of salts of carbonic
acid or carbonates, such as limestone, marble, and chalk.
[Sidenote: Various forms of carbon]
The pure element, carbon, is found in nature in the form of diamonds,
which are pure crystallized carbon. Small diamonds are now made
artificially in electric furnaces. Crystallized carbon also occurs
in nature in the form of graphite, from which lead pencils are made.
Charcoal, lampblack, and coke are forms of amorphous carbon which
contain a very small percentage of impurities.
[Sidenote: Properties of carbon]
Notwithstanding the marked difference in their appearance, the various
forms of carbon have some properties in common. They are insoluble
in all known liquids. They are tasteless, odorless, and infusible at
ordinary temperature. When heated without access of air, they remain
unchanged unless the temperature is very high, in which case they unite
with oxygen and are consumed, forming carbon dioxid.
INORGANIC CARBON COMPOUNDS
CARBON DIOXID (CO₂)
The principal compound of carbon and oxygen is carbon dioxid, often
called carbonic acid gas. This gas is always present in the air. It
issues from the earth in many places, particularly in the neighborhood
of volcanoes. With it many mineral waters are naturally charged.
[Sidenote: How carbon dioxid enters the air]
Carbon dioxid is constantly formed by many natural processes. Every
animal that breathes gives off carbon dioxid from its lungs. This gas
is also formed whenever ordinary combustible materials are burned. The
natural processes of decay of both vegetable and animal matter tend to
convert the carbon contained therein into carbon dioxid, which is thrown
off and absorbed into the air. The process of alcoholic fermentation,
and similar processes, also give rise to the formation of this gas.
When fruits ripen, fall, and decay, the sugar, which all fruit-juices
contain, is changed to alcohol and carbon dioxid.
RELATION OF CARBON DIOXID TO LIFE
[Sidenote: Action of plants upon carbon dioxid]
Carbon dioxid is an important factor in the life activity of the earth.
The leaves of plants absorb carbon dioxid from the air, and by means of
the chemical activity of the green coloring-matter or chlorophyl, the
plant has the power of combining the carbon dioxid with water, and with
the mineral salts which have been absorbed from the earth by the roots
of the plant. Sunlight is necessary to this action, especially in the
manufacture of starch.
This formation of food material in plants by the combination of simple
chemical substances, such as carbon dioxid and water, is one of the
fundamental life-processes. Animals do not possess this power of
utilizing simple or inorganic chemical compounds, therefore they must
take their food substances in the more complex forms which have been
created by the power of sunlight acting upon the plant.
[Sidenote: The wonderful carbon cycle]
I have already explained how carbon dioxid may enter the air. Thus we
see that the carbon dioxid which is withdrawn from the air, by the
growth of plants, is constantly replaced by combustion, and in this
way the "carbon cycle" is completed. This is one of the most beautiful
adaptations in nature. If the plant did not remove the carbon dioxid
from the air, it would soon accumulate in such quantities as to become
detrimental to life, and, on the other hand, if this gas were not
returned to the air by combustion, by the breathing of animals, and by
the decay of plants, the vegetable world would soon be without carbon
dioxid, which is as essential to plant life as is the oxygen of the air
to animal life.
CARBON MONOXID (CO)
This compound is formed when a substance containing carbon is burned
in an insufficient supply of air, as for example when the draught is
partly shut off in a stove.
[Sidenote: Properties of carbon monoxid]
Carbon monoxid is a colorless gas. It burns with a blue flame, forming
carbon dioxid. The blue flame seen playing over the embers of a coal
fire is carbon monoxid burning. This gas is extremely poisonous. Carbon
dioxid, CO₂, is not poisonous. The poisonous properties of illuminating
gas are due to the carbon monoxid which it contains.
ORGANIC CARBON COMPOUNDS
The carbon compounds thus far considered have been mentioned to
illustrate a few of the simpler or inorganic forms of carbon. We will
now begin the study of _organic chemistry_ or the compounds of carbon
which are commonly found only in plant and animal substances.
[Sidenote: Combining power of carbon]
Carbon has wonderful powers of combination with other chemical
elements, and may combine with the same elements in thousands of
different proportions. This property of carbon to form so many different
compounds is considered one of the fundamental facts of chemistry upon
which life depends. For example:
[Sidenote: Carbon and hydrogen compounds]
Oxygen can combine with hydrogen in but two
proportions--peroxid of hydrogen (H₂O₂) and water (H₂O)--while
carbon and hydrogen can combine in more than a hundred different
compounds. The simpler of these are acetylene (C₂H₂) and marsh gas
or methane (CH₄), which is the fire-damp in mines.
The compounds containing carbon, hydrogen, and oxygen number into the
thousands. A great many substances formed in plants contain these three
elements, such as fruit-acids, alcohol, sugar, and fats.
CLASSIFICATION OF ORGANIC CARBON COMPOUNDS
Only a few of the most important groups of the organic or life-formed
carbon compounds will be considered in this work, namely:
a Hydrocarbons
b Alcohols
c Glycerin
d Aldehydes and ethers
e Organic acids
f Carbohydrates
g Fats
a HYDROCARBONS
[Sidenote: Uses of hydrocarbons in industrial chemistry]
Hydrocarbons are compounds of the two elements carbon and hydrogen.
These compounds are very important in industrial chemistry. They are
found in petroleum, coal-tar, etc., which were originally formed from
decaying and petrifying masses of plants. Gasoline, benzin, naphtha,
acetylene, methane, etc., are some of the industrial forms by which
hydrocarbons are known in commerce.
[Sidenote: Coal-tar products]
The industries based upon the chemistry of these hydrocarbons are very
complex and interesting. Coal-tar yields, by repeated distillation and
chemical reaction, thousands of compounds, many of which find important
industrial usages. Coal-tar dyes are very numerous and of wonderful
coloring power. They have been extensively used in the artificial
coloring of manufactured foods. The Federal Pure Food Law attempted to
prohibit this. In fact, it was the pernicious effect and extensive use
of these poisons that stimulated the passage of the "Food and Drugs
Act." Another interesting product of the coal-tar industry is saccharin.
Saccharin has no food value whatever, but it is 280 times sweeter than
cane-sugar, and is therefore used as a substitute in sweetening some
prepared foods.
b ALCOHOLS
[Sidenote: Varieties of alcohol]
To the ordinary mind the term alcohol refers only to the intoxicating
element in liquors. To the chemist, alcohol has a much broader
significance. There are many varieties of alcohols, of which ethyl
alcohol (C₂H₅.HO), which is found in liquors, is only one example.
Another form of alcohol which is fairly well known is wood or methyl
alcohol (CH₃.OH).
[Sidenote: Formation of higher alcohols]
There are also higher alcohols, that is, those having more complex
chemical formulas, such as butyl alcohol. In the fermentation of grains
or fruits for intoxicating liquors, a small quantity of the various
higher alcohols is formed. These higher alcohols are more intoxicating
and more harmful to the human system than ethyl alcohol, and must
be separated from the latter by careful distillation. The poisonous
property of green whisky and cheap liquors is generally due to the
presence of higher alcohols.
Alcohol does not exist in normal, fresh plant or animal substances
except in very minute quantities. It is formed from sugar by
fermentation. This fermentation is due to a microscopic yeast-plant.
c GLYCERIN
Another form of alcohol is glycerin (C₃H₈O₃). It is of special interest
to the food chemist because it enters into the formation of all fats.
d ALDEHYDES AND ETHERS
[Sidenote: How formed]
These are compounds containing carbon, hydrogen, and oxygen, and are
closely related to alcohols. In fact they are formed from alcohols by a
process of oxidation, hence contain a little larger proportion of oxygen
than the related alcohol.
[Sidenote: Uses of formaldehyde]
An example of aldehyde with which many are familiar is formaldehyde,
which is used in laboratories for the preservation of animal-tissues
for dissection. This formaldehyde is a very strong germicide; that is,
it is poisonous to bacteria or germs. For this reason it is used as a
preservative of milk, a use which is forbidden by the "Food and Drugs
Act," because formaldehyde is also poisonous to the human system.
[Sidenote: Uses of ether]
Ethyl ether, which is used as an anesthetic or to produce insensibility
to pain, will serve as an illustration of this group of compounds. When
analyzing foods in chemical laboratories, ether is commonly used for
dissolving fats.
e ORGANIC ACIDS
[Sidenote: Properties of organic acids]
It will be remembered that acids were studied in the second lesson. It
was found that the common properties of acids are a sour taste, ability
to combine with alkalis in the formation of salts, and that all acids
contain hydrogen. These same properties that were studied in the second
lesson in reference to mineral acids, such as hydrochloric and sulfuric,
apply also to the organic acids. The organic acids, however, as a class
are not so strong or active as the mineral acids.
All organic acids are compounds of carbon, hydrogen, and oxygen, the
same as alcohols and ethers, the chief difference between these
compounds and acids being that the acids contain a greater proportion
of oxygen. One of the simplest organic acids is _formic acid_ (HCO.OH).
This acid is the active principle in the sting of the red ant, and also
of stinging nettles. It produces blisters when applied to the skin.
[Sidenote: Process of making acetic acid]
Impure _acetic acid_ (C₂H₄O₂) is very well known to all under the name
of vinegar. Acetic acid may be obtained by distilling wood. If it could
be manufactured cheaply enough, vinegar made from wood would be fully
as wholesome as the best cider vinegars, but this being an expensive
process of manufacture, the temptation of the food adulterator is to
make the vinegar of sulfuric acid, which is much cheaper than the mild
acetic acid, but much more harmful when taken into the body.
The formic and the acetic acids are examples of a series of organic
acids known as _fatty acids_. Other members of the series are--
Propionic acid C₃H₆O₂
Butyric " C₄H₈O₂
Palmitic " C₁₆H₃₂O₂
Stearic " C₁₈H₃₆O₂
[Sidenote: Process of making soap]
These fatty acids are very important to the food scientist as they
combine with glycerin to form fats. When combined with alkalis under a
certain temperature they form soap. Perhaps some of our older students
may remember the soap kettle on the farm at home, in which lard
cracklings and other fatty fragments of the animal were boiled with lye
or caustic potash to form home-made soap. The chemical action that took
place was a combination of these fatty acids with the caustic potash or
lye. The glycerin was set free and remained in the bottom of the kettle
as soft soap. Reference will be made to these acids again, in Lesson
IV, where the study of fats will be taken up in detail. (See "Fats and
Oils," under Lesson IV, Chemistry of Foods, p. 122).
[Sidenote: Oxalic acid]
There are some other forms of organic acids which do not belong in the
fatty series; that is, they do not contain the same general proportions
of carbon and hydrogen. One of these is oxalic acid (C₂H₂O₄) which is
found in certain plants, such as sorrel, and is an active poison. Oxalic
acid is used in the household for taking iron-rust out of cloth.
[Sidenote: Lactic, malic and tartaric acids]
Lactic acid (C₃H₆O₃) is the acid of sour milk. Malic acid (C₄H₆O₅) is
found in many fruits such as apples, apricots, currants, pears, plums,
prunes, etc. Tartaric acid (C₄H₆O₆) is found principally in grapes.
It is one of the constituent elements in the sediment found in wine
casks, and is the active principle in cream of tartar. The latter is a
potassium salt of tartaric acid.
[Sidenote: Citric acid]
Citric acid (C₆H₈O₇) is one of the most important of the organic acids
from the standpoint of the food chemist. It is the active principle of
citrus-fruits, such as grapefruit, lemons, limes, oranges, etc. Lemons
contain as high as five per cent of this acid. Citric acid is often used
to make lemonade, and if pure citric acid is used, the manufactured
product is equal to the original, except from a sentimental standpoint
of having the genuine. The danger is, as in the case of adulterated
vinegar, that the manufacturer may be tempted to use cheaper mineral
acids instead of citric acid.
The other above-named groups of organic compounds which are formed from
the three elements carbon, hydrogen, and oxygen--(f) _carbohydrates_
and (g) _fats_--are very important to the food chemist. These will be
considered in detail in Lesson IV. See pages 107-125.
ORGANIC NITROGENOUS COMPOUNDS
If to the three elements carbon, hydrogen, and oxygen, the element
_nitrogen_ is added, it still further increases the number of possible
compounds that may be formed upon the base of the wonderful _carbon
atom_. With this additional nitrogen factor, a new and a distinct
quality is obtained.
[Sidenote: The elements that make life possible]
The chief characteristic of the element nitrogen is the ease with which
its compounds change their chemical form. To quote the chemist, "the
compounds of nitrogen are very unstable." Nearly all explosives are
nitrogenous compounds. When this element, nitrogen, is combined with
the wonderful variety of compounds formed by carbon, we have not only a
great many intimately related yet distinct substances, but compounds
which readily change from one form to another. These are the distinctive
qualities or conditions necessary, from a chemical standpoint, to make
the processes of life possible. _Protoplasm, which is the basis of all
life, is formed by an intimate mixture of a number of complex chemical
compounds, the chief elements of which are carbon, hydrogen, oxygen, and
nitrogen._
[Sidenote: Importance of nitrogenous compounds]
The organic compounds containing nitrogen are very numerous and very
interesting. As all tissues and substances of the animal body contain
nitrogen as a necessary element, we can see why this group of compounds
is of great importance to the student of food science.
Some of the nitrogenous compounds which are _not_ available as nutritive
substances, and many of which are poisonous or harmful to animal life,
will be considered in Lesson IX, under "Alkaloids and Narcotics." (See
Vol. II, p. 349.) The principal nutritive substances, and proteids or
compounds containing _available food nitrogen_, will be considered in
Lesson IV.
LESSON IV
CHEMISTRY OF FOODS
[Sidenote: Four general classes of food]
The chemistry of carbon compounds and the general composition of
plant and of animal substances were discussed in Lesson III. We are
now prepared to take up the chemistry of food. The chemistry of
food substances will be considered under the common divisions of
carbohydrates, fats, proteids, and mineral salts. (See "Classification
of Organic Carbon Compounds," Lesson III, p. 89.)
[Sidenote: Classes vs. groups of related compounds]
In the food tables and analyses commonly published, the above terms are
used with very little explanation, and read by the average person with
meager comprehension. When one reads that a food is composed of glucose,
citric acid, or globulin, he is likely to become confused, not being
able to understand how a food at one time can be said to be composed of
carbohydrates, proteids, and fats, and at another time to be composed
of other substances. The explanation is that the first classification
does not refer to definite chemical substances, but to groups of related
compounds having properties in common.
[Sidenote: The different methods of analyzing food]
There is still another way of giving the chemical composition of a
food, namely, to specify the chemical elements that it contains. It
will be remembered that the relation between chemical elements and
chemical compounds was explained in the first lesson. As an example, I
will take the analysis of milk. We will first say that milk contains a
certain percentage of protein, carbohydrates, and fat. We might then
say that the proteid of milk is part casein and part albumin, and that
the albumin contains certain percentages of oxygen, sulfur, etc.; also
that the chief carbohydrate in milk is milk-sugar, which in turn is
composed of carbon, hydrogen, and oxygen. Or, we could consider the
milk as a whole, without dividing it into groups, and give the per cent
of each chemical element in the milk. Thus, the carbon of the proteid,
milk-sugar, and fat would be all considered together, and show a certain
per cent of carbon in the milk as a whole.
CARBOHYDRATES
The word _carbohydrate_ means _carbon combined with water_; that is, the
element carbon is combined with hydrogen and oxygen, which exist in the
carbohydrate compound in the same proportion as they exist in water.
The carbohydrates are closely related chemically to the aldehydes and
the alcohols, so far as their composition is concerned (See "Aldehydes
and Ethers," Lesson III, p. 93), but this does not imply that they have
the same physiological effect in the animal body.
CLASSIFICATION OF CARBOHYDRATES
The carbohydrates are divided by the chemist into three classes known as
a MONOSACCHARIDS
b DISACCHARIDS
c POLYSACCHARIDS
The principal subdivisions found in these classes of carbohydrate
foods are given in the following table, arranged in the order of their
importance:
Monosaccharids Disaccharids Polysaccharids
______________ ____________ ______________
1 Glucose or grape-sugar 1 Cane-sugar 1 Starch
(formerly
called dextrose)
2 Pentoses 2 Maltose 2 Glycogen
(of which there
are several) 3 Lactose 3 Cellulose
3 Levulose 4 Gums
4 Galactose 5 Inulin
a MONOSACCHARIDS
1 GLUCOSE OR GRAPE-SUGAR (C₆H₁₂O₆)
Glucose or grape-sugar is the most important sugar known from the
standpoint of the physiological chemist. This sugar is normally found
in considerable quantities in human blood, and is absolutely essential
to the life-process, a fact which forms an amusing contrast with the
popular conception of the term glucose as something injurious or
poisonous.
[Sidenote: Sources of glucose]
Glucose is found in honey, and in nearly all fruits, grains, and sweets.
(For "Sweets" see Lesson VIII, Vol. II, p. 324). It may be taken into
the human body directly from such fruits, or it may originate by the
digestion of other carbohydrates.
Pure glucose crystallizes and resembles cane-sugar, but is not so sweet.
The glucose of commerce, sold as sirup, is a product manufactured from
corn, or other starches, and will be considered more in detail under the
heading _starch_. (See "Polysaccharids," p. 114).
2 PENTOSES (C₅H₁₀O₅)
[Sidenote: Sources of pentoses]
Pentoses form a group of sugars, the chemical formula of which contains
five atoms of carbon. Each different pentose could be studied in detail
by the chemist, but the pentoses are of no particular interest to the
food scientist. They exist, however, in the coarse parts of plants,
such as stalks and leaves, and are of considerable importance in animal
feeding. From the standpoint of human food we will remember that the
carbohydrates of green plants contain a percentage of these pentoses,
but as they are never removed from the plant separately, as are other
sugars, we must consider their physiological effect in the particular
plant rather than separately.
3 LEVULOSE (C₆H₁₂O₆)
This is the companion sugar to glucose and exists in many fruits.
Levulose is often called "fruit-sugar." The composition of levulose is
exactly the same as glucose, but the atoms are combined in different
ways.
Levulose, for all practical purposes, may be considered the equivalent
of glucose in the human body. It is sweeter than glucose and more
closely resembles cane-sugar.
4 GALACTOSE (C₆H₁₂O₆)
Galactose, which is of the same composition as levulose, is another
companion sugar to glucose, and is formed by the digestion of lactose or
milk-sugar.
b DISACCHARIDS
1 CANE-SUGAR (C₁₂H₂₂O₁₁)
Just as there are three monosaccharid sugars with six carbon atoms
each, so there are three disaccharid sugars which have twelve carbon
atoms each. The first of these is cane-sugar. It is commercially made
from either sugar-cane or sugar-beets, and is identical in chemical
composition from either source.
Cane sugar, when digested in the human body, or by artificial means,
combines with water, and forms glucose and levulose, as shown by the
following equation:
C₁₂H₂₂O₁₁ + H₂O = C₆H₁₂O₆ + C₆H₁₂O₆
Cane-sugar + Water = Glucose + Levulose
2 MALTOSE (C₁₂H₂₂O₁₁)
[Sidenote: Maltose--how formed]
Maltose is the second member of the disaccharid group, and is of the
same composition as the other two. Maltose derives its name from malt.
It is formed from the starch of grains by a process of digestion which
may be performed in the animal body, or by the process of malting.
Maltose, like cane-sugar, can be further digested into monosaccharid
sugars, but upon such digestion, instead of forming two separate simple
sugars, it is wholly converted into glucose.
The reader will now understand the meaning of the terms _monosaccharid_,
_disaccharid_, and _polysaccharid_. MONO, which means _one_, is the
simplest form of carbohydrates. Disaccharids (DI, meaning _two_), split
up to form two simple sugars. Polysaccharids (POLY, meaning _many_) are
complex compounds which form many simple sugars.
3 LACTOSE (C₁₂H₂₂O₁₁)
Lactose exists in milk and has the same formula as cane-sugar. Milk
contains about five per cent of this sugar.
When lactose is digested it combines with water as does cane-sugar,
but instead of yielding glucose and levulose, it yields glucose and
galactose.
c POLYSACCHARIDS
1 STARCH
The chemical formula of starch and other polysaccharids is written
(C₆H₁₀O₅)n. This means that the proportion of the elements is according
to the figures given, but the number of atoms that are supposed to be
combined is many times greater than five, and is not accurately known.
This is purely theoretical, and of no practical importance, except that
it shows that the polysaccharid is capable of being digested or broken
up into many simple carbohydrate compounds.
[Sidenote: Sources of starch]
Starch is the most abundant carbohydrate known. It is the chief
constituent of all cereals, and is found in large quantities in green
fruits and tuberous plants. Starch occurs in small granules, varying
greatly in size in different foods.
[Sidenote: Potato starch]
Potatoes are composed chiefly of starch and water. The starch grains of
potatoes can almost be distinguished with the naked eye. These starch
granules are not atoms or molecules in the chemical sense, but are small
receptacles in which starch has been deposited by the growing plant.
When cooked or boiled in water these starch grains swell into a mushy,
pasty or gelatinous mass; when cooked in dry heat until they begin to
turn brown, they are changed into a compound related to the gum group,
known as dextrin.
[Sidenote: Solubility of starch]
Starch does not dissolve in water as do sugars. If starch is treated
with digestive fluids, such as saliva, or with certain acids, it goes
through a complex process of digestion in which it is first turned into
soluble starch, then into the various forms of dextrin or gums, and
finally into maltose or malt-sugar.
[Sidenote: How corn-starch is changed into glucose]
Corn-starch, treated with weak sulfuric acid, changes the starch into
glucose. The ordinary glucose or corn-sirup is not all changed by this
process, into pure glucose, but contains some maltose and other gummy
compounds; hence it will not crystallize or granulate into pure sugar.
After the acid has changed the starch into glucose it (the acid) is
neutralized with an alkali. A crude compound is thus formed, which
settles to the bottom of the tank, and from which the glucose can be
easily separated. Commercial glucose is now very extensively used in
the manufacture of various food products, especially confectionery.
Pure glucose is a wholesome food, but there is some danger that the
commercial product may (due to carelessness in manufacturing, or to
the use of cheap and impure acid) contain various mineral poisons.
Government testing of glucose and similar manufactured products is, in
the writer's opinion, fully as essential as the government inspection of
packing-house products.
[Sidenote: How starch is changed into maltose]
Just as glucose may be manufactured from starch treated with dilute
acids, so maltose may be made by treating starch with malt. The brewing
of beer depends upon the chemical changes induced in starch by malt.
Barley is ordinarily used for this purpose. The barley is sprouted in
a warm, damp room, and a process of starch digestion begins, which is
necessary in order that the young barley sprouts may grow. This changes
the starch into maltose. The digestive principle developed in the
barley-malt may be utilized to malt other grains by mixing them with the
sprouted barley.
[Sidenote: Maltose in foods]
If this process of malting is stopped at the proper time, and the sugar
dissolved, and extracted, a product is formed consisting chiefly of the
sugar maltose. This is the basis of malt extract, malt honey, and many
similar foods put on the market, which are claimed by the manufacturers
to have wonderful dietetic and curative values.
2 GLYCOGEN
[Sidenote: Glycogen--how formed and where stored]
Glycogen is commonly called animal-starch. It exists in the liver in
small quantities. All carbohydrates are digested in the alimentary canal
and absorbed into the blood in the form of simple sugars of the glucose
group. When these sugars reach the liver they are again built up into
a complex carbohydrate very similar to starch in composition. This
glycogen or animal-starch is stored in the liver until the body has
need of it, when it is changed into glucose and given back to the body
in the form of energy. (See "Metabolism of Carbohydrates," Lesson VI, p.
202).
3 CELLULOSE
[Sidenote: Cellulose--its purpose, source, and importance]
Cellulose, from the standpoint of human nutrition, is not a food
product, being insoluble by the digestive juices, but it is very
important in the digestion and the alimentation of other foods. Its
chief purpose is to excite stomach and intestinal peristalsis. All
plant products in their natural form contain some cellulose, though the
percentage is very small in such grains as rice and barley. The bran of
wheat or of corn is chiefly cellulose. Wood is almost pure cellulose.
Cellulose can be digested by strong acids into simple carbohydrates, in
the same way that starch may be. Sugar can be manufactured from wood or
rags, but the process is yet too expensive to be applied commercially.
Some of us may live to see the time when the chief food of mankind
will be manufactured from scrap lumber and waste paper. Bacteria have
the power of digesting cellulose. The bacterial action or fermentation
in the human intestines may cause a small amount of cellulose to be
digested, but the quantity is of no consequence from a nutritive point
of view.
4 GUMS
The gums include a group of rather complex carbohydrates which are
intermediate between starches and sugars. From plants are derived many
varieties of gums which have various commercial uses in the market, such
as gum arabic.
I have already spoken of the formation of dextrin from starch. Dextrin
has no particular dietetic qualities that do not exist in starch. It
is, in fact, starch arrested at an intermediate point of digestion.
[Sidenote: Pectins in fruits]
Pectins are a group of gummy substances found in fruits, especially
green fruits which are in the process of being formed into sugar.
These pectins form the basis of fruit jellies. Green grapes, as every
housewife knows, will make better jelly than ripe grapes. This is
because the pectins in ripe grapes have been transformed into sugar. The
pectins in fruit are in most cases wholesome enough, though it would
seem the better part of wisdom to eat all fruits in the ripened state,
after Nature has completed her work.
5 INULIN
Inulin is a compound closely related to starch, and upon digestion with
acids, yields levulose just as starch yields glucose. It is of no
particular interest to the food chemist, as it exists in but very small
quantities in starch, and has no distinct dietetic value.
FATS AND OILS
[Sidenote: Composition and formation of fats and oils]
The fats and oils in food products, whether of plant or animal origin,
contain the elements carbon, hydrogen, and oxygen. These fats are
formed by uniting the fatty acids with glycerin, which belongs to the
alcohol group. The particular fat that is formed takes its name from the
acid which enters into its composition; thus stearic acid unites with
glycerin to form the fat stearin.
The following table gives the names of a few of the more common fatty
acids and their corresponding fats:
Stearic acid Stearin
Palmitic acid. Palmitin
Oleic acid Olein
Butyric acid Butyrin
[Sidenote: Distinction between tallow and lard]
A fat from any source will usually contain several of these chemical
compounds. The ordinary animal fats, such as tallow and lard, are formed
chiefly of the two fats stearin and olein. The different proportions of
these fats will determine the melting point or hardness of the mixed
product. Olein is a liquid at ordinary temperature, while stearin is
solid. The reason that tallow is a firmer fat than lard or butter is
because it contains a larger per cent of stearin.
Olive-oil, cottonseed-oil, and other vegetable oils contain large per
cents of olein, which accounts for their being liquid at ordinary
temperature.
[Sidenote: Dairy butter vs. artificial butter]
Butyrin is a fat found in small quantities in dairy butter, and does
not exist in cottonseed-oil and other fats from which oleomargarin is
manufactured. This is the reason that artificial butter lacks the flavor
of the dairy product, and this is remedied to some extent by churning
the fats of the cottonseed-oil and tallow with fresh cream, which
imparts a small quantity of the butyrin and similar compounds to the
oleomargarin and gives the characteristic flavor of butter.
[Sidenote: Oils as active poisons]
Besides the more common fats herein mentioned there are many other fats
that exist in certain vegetable oils in small proportions. These fats
give the oils their characteristic properties, and may render them unfit
for food. Some oils are active poisons, such as croton-oil, which is the
most powerful physic known. The power of all physics and cathartic drugs
is measured by the active poisons they contain.
[Sidenote: Packing-house uses of stearin and olein]
When fats are heated to a high temperature they decompose and form
various products, some of which are irritating and poisonous to the
human system. In the manufacture of packing-house and cottonseed
products the stearin is often separated from the olein. The granular
appearance of pure leaf lard is due to crystals of stearin. In the
packing-house stearin is separated from the tallow in large quantities.
The stearin is used to make candles, etc., while the olein is used
for food purposes in this country in the form of oleomargarin, while
in Europe it is used under its right name as a cooking product. It is
equally as wholesome, if not more so, than lard.
[Sidenote: Rancid fats made edible]
Fats may become rancid; this is caused by the decomposition of fat due
to its uniting with the oxygen of the air. Rancid fats and nut-kernels
can be restored and made edible by heating them in an oven until the
oxidized fat is neutralized by the heat.
PROTEIDS OR NITROGENOUS FOOD SUBSTANCES
[Sidenote: Proteids defined]
The food substances which contain nitrogen are commonly called
proteids, or, if these compounds are considered together, the name
protein may be given the group. Protein is not a single compound, but
includes all substances which contain the element nitrogen in such
combinations as are available for assimilation in the human body.
[Sidenote: Only proteid foods contain nitrogen]
Protein is the most important group of nutrients in the animal body. The
proteid substances in the body must be formed from proteids taken in the
form of food, because only proteid foods contain the element nitrogen.
All proteids contain nitrogen, but all nitrogen does not contain
protein. All proteids, therefore, are nitrogenous compounds.
[Sidenote: Formation of organic nitrogen]
The animal body does not possess the power of combining elementary
nitrogen with other elements. Bacteria have the power to utilize the
nitrogen of the air to form mineral salts or nitrates. Plants have the
power to unite the nitrogen derived from these nitrates with carbon,
oxygen, and hydrogen. In this way organic nitrogen, or proteids,
are formed. The animal body may digest these proteids, however, and
transform them into other proteid compounds. All proteids contain
carbon, hydrogen, oxygen and nitrogen; most of them contain sulfur, and
a few contain phosphorus, iron, copper, and bromid.
The percentage by weight of the various elements which form proteid
matter is about as follows:
Carbon 52%
Hydrogen 7%
Oxygen 22%
Nitrogen 16%
Sulfur 2%
Phosphorus 1%
The following table gives three groups of proteid substances:
_Simple Proteids_
Albumins
Globulins
Nucleo albumins
Albuminates
Coagulated proteids
Proteoses (Albumoses)
Peptones
_Compound Proteids_
Respiratory pigments
Gluco Proteids
Nucleins
Nucleo proteids
Lecith albumins
_Albuminoids_
Collagen
Gelatin
Elastin
Reticulin
Keratin
[Sidenote: Amido compounds]
Besides these real proteids there are a few substances known as amido
compounds which exist in small quantities in vegetables, and a number of
nitrogenous substances which exist in meat and meat extracts, which are
not true proteids, as they have little or no nutritive value, but act as
stimulants or irritants in the body.
[Sidenote: Ptomains--how formed]
Ptomains are another class of substances which are often found in food
products. They are formed by the growth of bacteria, and are in reality
the nitrogenous waste-products of bacterial life. Ptomains develop in
meats and dairy products held in cold storage, and are sometimes the
cause of serious poisoning. Nitrogenous waste-products will be further
discussed in Lesson VI, under "Metabolism of Proteids." (See p. 209.)
[Sidenote: Sources, coagulation and solubility of albumin]
Albumin is one of the commonest and simplest forms of proteids known. It
is found in the white of eggs, in milk, and in blood. It is coagulated
by heat, and by certain chemicals, such as acids, alcohol, and strong
alkalis. Albumin is soluble in water and in weak solutions of salt, but
it is not soluble in very strong salt solutions.
[Sidenote: Sources and properties of globulins]
Globulins are much like albumin, but are not soluble in water. They
are, however, soluble in dilute salt solutions. Globulins exist in
considerable quantities in the yolk of eggs, and in the blood. The
globulin in the body could not remain in solution if there were not
always present a small quantity of salt in the blood. There are several
types of globulins. The fibrinogen of the blood, which coagulates,
forming clots, when the blood is exposed to the air, is a globulin.
Hemoglobin, which is the chief component of red blood-corpuscles, and
which unites with the oxygen in the lungs and carries it to the various
tissues of the body, is another form of globulin, and one which contains
a considerable amount of iron.
[Sidenote: Sources of casein]
Casein is the most important proteid substance in milk, and is familiar
to all as the curd or white substance of clabbered milk. A related form
of vegetable casein is found in leguminous seeds, such as beans and peas.
[Sidenote: Sources of proteoses and peptones]
Proteoses and peptones are proteids that are formed by the digestion
of other proteids. They exist in the alimentary canal in the partly
digested food. Peptones are readily soluble, and for this reason are
easily absorbed through the walls of the digestive organs. (See Lesson
V, "Digestive Organs"--[The Stomach], p. 137; also "Composition of
Gastric Juice," p. 147).
MINERAL SALTS IN FOOD
[Sidenote: Vegetable mineral salts vs. common table salt]
[Sidenote: Foods containing mineral salts]
The subject of salt in food has received considerable attention and
discussion by scientific investigators, and many theories have been
advanced by those interested in hygiene as to the effect of common
salt used in food. The tissues and organs of the body contain certain
salts, without which life could not exist, but it does not follow that
these salts need to be supplied in mineral form. Common table salt is
an inorganic substance, while the mineral salts in green and fresh
vegetables are organic, and readily convertible, therefore a valuable
aid in the digestion of other foods. A diet of sugar, pure oil, and
artificially prepared proteids would be absolutely unwholesome and
would fail to nourish the body for any length of time because of
the lack of mineral salts. All natural food products, whether of
vegetable or animal origin, contain a limited but ever-present amount
of mineral salts. This is especially true of milk, eggs, and the seeds
and green portion of plants. The amount of salts in the human body is
considerable, especially the calcium phosphates of the bones, but the
salts that need to be supplied daily in food is small because the salts
are not consumed as rapidly as are other elements of nutrition.
[Sidenote: Grains deficient in salt]
Some grains, especially rice and corn, are somewhat deficient in salts.
At the Kansas Experiment Station some pigs were fed exclusively on corn,
and others on grain and green forage. At a certain age the pigs were
killed, and the bones weighed and tested for strength. The bones of the
pigs which had been fed on a corn diet, which is deficient in mineral
salts, were about half as heavy and strong as the bones of the pigs fed
in a more natural way.
LESSON V
CHEMISTRY OF DIGESTION
DIGESTIVE ORGANS AND DIGESTIVE JUICES
FIRST--THE MOUTH:
The three salivary glands of the mouth
secrete the saliva, which is an _alkaline_
substance containing a digestive enzym
called ptyalin.
The saliva begins the digestion of starch
and moistens food to facilitate swallowing.
SECOND--THE STOMACH:
The gastric juice secreted by the mucous
lining of the stomach is an _acid_. It contains
hydrochloric acid and pepsin, which
act on proteids, changing them to _proteoses_
("intermediate products formed naturally
in the process of digestion") and peptone.
The gastric juice also contains _rennet_,
which acts directly on milk, and indirectly
on all proteids.
THIRD--THE LIVER:
The liver secretes a digestive fluid called
bile, which is an _alkaline_ substance. Its
chief purpose is to emulsify fats and to
supply the alimentary tract with the
requisite amount of moisture.
FOURTH--THE PANCREAS:
The pancreatic juice, secreted by the
pancreas, is an _alkaline_ and slightly _acidulous_
substance. It contains three enzyms,
the names and action of which are as
follows:
Amylopsin completes the digestion of
starch.
Trypsin completes the digestion of proteids.
Steapsin converts fats into fatty acids
and glycerin.
FIFTH--THE SMALL INTESTINES
The intestinal juices secreted by the
small intestines are _alkaline_ substances
which change sugar and maltose into glucose,
and perform the last step in the process
of breaking up or subdividing food so
fine that it will pass through the intestinal
walls into the circulation.
LESSON V
CHEMISTRY OF DIGESTION
[Sidenote: Alternation of digestive juices]
The digestive juices of the human body are five in number, namely:
Saliva, gastric juice, bile, pancreatic juice, and the several
intestinal juices. Beginning with the saliva these juices alternate,
first an alkali, then an acid. It is the opinion of the writer that this
alternating plan is carried on throughout the entire intestinal tract,
as the final dissolution of food matter takes place in the intestinal
canal. These five juices are secreted from the blood by special cells
or glands. Each of these juices contain one or more enzyms or digestive
principles. These enzyms are highly organized chemical compounds which
have the property of changing other chemical compounds without being
destroyed or used up themselves except in minute quantities.
[Sidenote: Malt and yeast-cells]
Malt, which was studied in the last lesson, and which is produced by
the sprouting of barley, is a true digestive enzym of the barley.
Yeast-cells are minute plants which secrete an enzym that causes the
fermentation of bread. It was formerly thought that the fermentation of
yeast could not take place except in the presence of a living cell. This
has now been disproved, as a German scientist has succeeded in grinding
up yeast-cells and filtering off the chemical compound or true enzym
which causes the fermentation of sugar.
[Sidenote: Fermentation due to enzyms]
It is now recognized by scientists that all processes of fermentation
and digestion found in plant and animal life are due to definite
chemical compounds known as enzyms. The action of digestion is truly a
chemical one, and could take place without the body as well as within,
if we could manufacture the proper enzym and could produce the exact
conditions of temperature, moisture, etc., that are found in the human
digestive economy.
[Sidenote: Predigested foods]
The manufacture of predigested foods depends upon various processes of
fermentation, or upon the digestion that may be carried on by inorganic
chemical agents, such as acids, or by the ferments of bacteria, or other
forms of life. The following are illustrations of these processes of
predigestion:
1 The manufacture of glucose from starch by the action of
sulfuric acid
2 The malting of starch for the production of malt-sugar or of
fermented liquors
3 The making of cheese by the action of the enzym rennet which
has been extracted from the stomach of a calf
A great amount of discussion, pro and con, has been raised over the
subject of predigested food. The foregoing examples will show that the
subject of predigested food, taken in its broadest sense, cannot be
dismissed summarily with either approbation or disapproval. We must
consider the particular chemical process involved in each case and the
final chemical products, as well as its mechanical condition. These
things must be taken into consideration when we pass an opinion upon the
wholesomeness of a so-called predigested food.
With this diversion to illustrate the breadth and the importance of the
action of enzyms, I will now return to the consideration of the chemical
action of the human digestive organs.
SALIVA
[Sidenote: Starch digestion in the mouth]
The saliva is the digestive juice of the mouth. It is secreted by three
pairs of salivary glands. The secretions from these three glands
are slightly different in composition, but for our purpose may be
considered as one secretion. The saliva is an alkaline fluid, and the
principal enzym that it contains is a starch-digesting enzym known as
ptyalin, which can act only in an alkaline solution. As the gastric
juice is strongly acid, the digestive action of the saliva is stopped
soon after the food has entered the stomach, and the enzym is of no
further use. The action of the saliva is very weak, and the amount of
starch digestion which is accomplished in the mouth is comparatively
insignificant.
[Sidenote: Saliva and mastication]
The chief function of the saliva is to moisten food and to facilitate
swallowing. From these statements one might first infer that the
emphasis given to thorough mastication is unwarranted. In fact, the
mastication of food has a much more important function than the
digestion of starch by saliva. This subject will be referred to again
when the physical condition of food as a factor in digestion, and
the nervous control or co-ordination of the various functions of the
digestive system are considered. (See "Composition of Gastric Juice," p.
147.)
GASTRIC JUICE
[Sidenote: Chief function of the stomach]
The importance of the stomach as an organ of digestion has been
overestimated in modern times. From the discussions in the average
text-book and physiology, one would be led to believe that the stomach
is the only organ of digestion, when, as a matter of fact, the chief
purpose of the stomach is that of a receptacle for the storage of food
for digestion further on. I do not mean by this statement that there is
no digestive action in the stomach, but I do mean to say that there
are no digestive processes completed in the stomach, and that all foods
which are acted on by the gastric juice can also be acted on by the
digestive juices in the intestines. This has been proved by the fact
that surgeons have successfully removed the entire stomach from both
animals and men without seriously interfering with the nutrition of
the body. They merely had to eat more often, as the depot or storage
receptacle had been removed.
[Sidenote: Inaccuracy of digestive tables]
The stomach should be considered as a preliminary organ of digestion.
The tables published in the physiologies giving the digestibility of
various foods as so many hours, refer entirely to the length of time
it takes for the food to pass out of the stomach. According to these
tables boiled rice is given as one of the most digestible of foods. As a
matter of fact, the chief reason why rice passes out of the stomach more
quickly than other grains, is because it contains practically nothing
but starch, and as starch is not digested in the stomach, the rice is
passed on to the next station where it can be acted on by an alkali.
[Sidenote: Comparison of predigested and uncooked cereals]
In this connection it becomes necessary to refer to the interpretation
of the experimental results obtained by investigators at the Battle
Creek Sanitarium. In these experiments cereal products which had been
put through various processes of predigestion were compared with
uncooked whole wheat, the contents being removed from the stomach after
a given period. The results of this experiment showed a greater amount
of starch digestion in the case of the dextrinized or super-cooked
foods. These results were published as proof that starchy foods
should be put through a process of super-cooking, dextrinization or
predigestion. To those who are not familiar with food chemistry, such
results would appear very convincing, but to a well-informed food
scientist they only illustrate how misinterpretation of scientific facts
may indicate conclusions opposed to the truth.
Starchy foods are not intended by Nature to be digested in the stomach,
but in the intestines, and the processes of partial digestion of these
foods, by artificial means, before entering the stomach, serve only to
interfere with Nature's plan, and to deprive both the stomach and the
intestines of their natural functions.
COMPOSITION OF THE GASTRIC JUICE
[Sidenote: Action of pepsin on proteids]
[Sidenote: Peptone and proteoses]
The gastric juice contains three principal enzyms or digestive
principles. These are hydrochloric acid, pepsin, and rennet. The
hydrochloric acid and the pepsin are secreted by different cells, and
could be considered as separate digestive juices, but as the action of
one is dependent upon the other, I will consider these actions as one.
Pepsin, in the presence of hydrochloric acid, acts on proteids, and
changes them into proteoses and peptone. Comparatively little food is
completely peptonized in gastric digestion. Proteoses are intermediate
products between food proteids and peptone, being the principal
product of the action of the gastric juice. Thus it is seen that this
stomach-action is only preparatory for the digestive processes of the
intestines.
[Sidenote: Action of gastric juice on fat]
The gastric juice does not act on fat, but in the case of animal food,
in which the membranes or connective tissues that enclose the fat-cells
are formed of proteid material, the gastric juice sets the fat-globules
free by dissolving these enclosing membranes.
[Sidenote: Purpose of hydrochloric acid]
The chief action of hydrochloric acid in the stomach is to aid the
action of the pepsin. Pepsin alone has no digestive power. There are no
other acids produced by the secretive glands of the stomach. If other
acids are found in the contents of the stomach, it is because they have
been taken in with the food, or produced by abnormal fermentation.
[Sidenote: How hydrochloric acid is formed]
The source of hydrochloric acid is from the sodium chlorid or common
salt of the blood. The secreting cells of the stomach-glands are thought
to have the power to form hydrochloric acid by uniting the chlorin of
the salt with the hydrogen of the water. This is a very unusual chemical
process, and has not yet been successfully produced in a laboratory.
[Sidenote: Hydrochloric acid as an antiseptic]
One of the chief functions of hydrochloric acid in the stomach is that
of an antiseptic. In other words, hydrochloric acid kills bacteria. This
is not true of all bacteria, for some germs can live in an acid medium,
while others may live best in an alkaline solution. The alternation of
the digestive juices from alkali to acid is a provision of Nature which
has a dual purpose:
1 To reduce food to the finest possible solution; that is, to
subdivide or to digest food elements into a form that will admit of
assimilation and use
2 To destroy bacteria and enzyms of plant and animal origin
that are taken into the digestive tract with food
(These two facts constitute additional reasons for the
thorough mastication of food)
[Sidenote: Object of alternating digestive juices]
By such plan Nature provides for the digestion of food only by such
enzyms and ferments as will produce a finished product wholly suited
to the particular requirements of the body. When we attempt by
artificial processes to digest our food with other enzyms than those
of our own digestive organs, or take into the stomach large quantities
of food without proper mastication, which causes fermentation, we may
expect that the nutritive material supplied to our tissues will not be
perfectly adapted to the needs of human cell-growth, and, as a natural
result, consequent derangement of the body-functions will take place.
[Sidenote: Rennet]
The rennet of the gastric juice is primarily for the purpose of
digestion. Other than this it has no particular function that has yet
been discovered.
[Sidenote: Why stomach does not digest itself]
The problem as to why the stomach does not digest itself has puzzled
scientists for many years. Investigations of the twentieth century
have at last solved this fascinating question. The walls of the human
stomach are composed of proteid material, and should be dissolved by
the gastric juice according to all known chemical laws. The explanation
formerly given was that the stomach did not digest itself because it was
alive. This answer did not satisfy scientists.
[Sidenote: Antipepsin in the blood]
There has recently been discovered an enzym, known as antipepsin,
which is secreted by the cells in the stomach-walls. This antipepsin
destroys the action of the pepsin, thus in turn preventing its action
on the stomach-wall itself. Were antipepsin secreted in sufficiently
large quantities to mix with the food in the stomach-cavity, no
digestion could take place. The presence of this antipepsin in the
stomach-walls has been proved in the following manner: The arteries
leading to a portion of the stomach-wall of a dog was severed. This
portion, receiving no blood supply, did not form the usual amount of
antipepsin. The secretion of pepsin went on in the remainder of the
animal's stomach, but digested that portion of the stomach-wall which
was receiving no blood supply; that is, secreting no antipepsin.
BILE
[Sidenote: Function of bile]
The bile is a juice secreted by the liver and is alkaline in character.
It is collected by the biliary ducts to be conveyed into the duodenum.
The most important constituents of bile are bile salts and sodium
glycocholate. The chief purposes of bile are to emulsify fats, thus
aiding them to pass through the intestinal walls, and to stimulate
intestinal peristalsis.
PANCREATIC JUICE
[Sidenote: Function of the pancreas]
The pancreas is a secretive gland located entirely outside of the
intestinal walls, and produces a juice which is poured into the small
intestines at the point where the bile enters. Pancreatic juice is
acidulous, and also strongly alkaline. As soon as the food, passing from
the stomach, comes in contact with the pancreatic juice and the bile,
the acid is neutralized, and the mass becomes alkaline.
The pancreatic juice contains three important enzyms:
1 Amylopsin--acts on starch
2 Trypsin--acts on proteids
3 Steapsin--a fat-splitting enzym
Pancreatic juice also has the power of coagulating milk, and is believed
to contain some rennet.
[Sidenote: Power of amylopsin]
Amylopsin, the starch-digesting enzym, appears to be very similar to
ptyalin in its power to digest carbohydrates. Amylopsin completes the
digestion of starch that was begun by the saliva. It acts on starch
with great activity. One part of amylopsin can change forty thousand
times its bulk of starch to glucose. This can act only in an alkaline
solution, and if any abnormal fermentation takes place in the digestive
tract, producing a large quantity of acids, the digestion of starch is
stopped. It is interesting to note that this enzym is entirely absent
from the pancreatic juice of infants. This explains why infants cannot
digest starch.
[Sidenote: Comparison of trypsin and pepsin]
The second enzym to be considered in the pancreatic juice is trypsin.
This is a substance distinct from pepsin, but its action is the same.
The chief distinction is that trypsin acts in an alkaline solution,
while pepsin acts in an acid solution. Trypsin is much more energetic in
its digestive power than the pepsin of the gastric juice. It completes
the digestion of proteids that is begun in the stomach, and converts
all proteids into soluble forms. A number of forms of proteid that are
not acted on at all by the gastric juice are readily digested by the
trypsin of the pancreatic juice.
[Sidenote: Fat digestion and absorption]
The fat-digesting enzym of the pancreatic juice is steapsin. This is the
principal fat-digesting enzym of the body. This substance has power to
split fats; that is, to convert them into fatty acids and glycerin of
which they were originally composed. This fatty acid then combines with
the alkalis of the bile and of the pancreatic juice to form soap. Soap
is soluble, and passes through the walls of the small intestines in this
form. Having passed through the walls of the intestines, soap is again
changed into fat. The probable reason for which Nature adopts such a
complex process for the absorption of fat, is because fat is insoluble.
If the intestinal walls were so constructed that fat-globules could be
taken directly through them, they would also be open for the entrance of
germs and other foreign substances.
[Sidenote: Frying fat unwholesome]
Fat is not acted on by the gastric juice. This explains why the process
of frying is so unwholesome. Frying causes a thin film of melted fat to
spread over the surface of the starch and of the proteid atoms, with the
result that these atoms cannot then be properly acted on by the saliva
and the gastric juice, and therefore cannot undergo the preliminary
changes necessary to normal digestion. Fat, taken in its natural form,
does not interfere with other digestive processes.
INTESTINAL JUICES
In addition to the digestive juices that are poured into the small
intestines from the pancreas and the liver, there is a juice which
is secreted from the walls of the intestinal cells. This is called
intestinal juice or succus entericus. It is a light yellow fluid with a
strong alkaline reaction, due to the presence of sodium carbonate.
One action of the intestinal juice is to change sugar and maltose into
glucose, which is then absorbed directly into the blood.
THE SECRETION OF DIGESTIVE JUICES
[Sidenote: Recent discoveries concerning digestive juices]
Within the past few years many remarkable discoveries have been made in
regard to the secretion of the various digestive juices. Until some ten
or fifteen years ago it was believed that the secretion of the digestive
juices depended wholly upon the presence of food in the alimentary
canal. The recent discoveries in this branch of physiology are to be
accredited chiefly to Professor Palloff, a Russian scientist, and his
co-workers. The facts that are now known regarding this part of Nature's
work are essentially as follows:
The secretion of the various substances which make up the digestive
fluids of the body depend upon two kinds of stimuli:
1 Direct nerve stimulus from the central nervous system
2 The chemical stimulus on the walls of the digestive organs
Depending upon either or both of these sources of stimulation, the
digestive juices of the body are regulated in quantity, and what is
much more worthy of note, in their actual chemical composition. Thus
it will be readily seen how far-reaching in its effect upon scientific
dietetic treatment is the knowledge of the influence of various foods,
quantities, and combinations.
[Sidenote: Comparative digestibility of foods]
Professor Palloff's discoveries throw some very important light on the
comparative digestibility of foods. The former method of estimating
the digestibility of food was first to analyze the food, and then to
analyze the intestinal residue, and subtract the undigested remnant of
each particular class of food from the amount originally eaten. By such
means it was possible to show that certain foods were, say 80 or 90 per
cent digestible, as the case might be. By this method no allowance was
made for the amount of nutrition or material that was consumed by the
body in the digestion of these particular foods. According to these
investigations, milk and meat were about equally digestible. It was not
known that the digestion of milk requires only a small fraction of the
energy that is necessary to digest meat, or proteids from vegetable
sources. Thus it is obvious that when it is desirable to get a large
amount of available nitrogen into the system, with as little expenditure
of energy as possible, milk is a food par excellence. This is very
logical inasmuch as the sole purpose of milk is food for animal life.
[Sidenote: Comparative acidity and energy required in digestion]
The amount of acidity in gastric juice that must be secreted for the
digestion of meat is much in excess of that required for a given amount
of vegetable food. The amount of acidity required is greatest for milk,
second for meat, and least for bread. The digestive energy required is
greatest for bread, second for meat, and least for milk. From this we
learn that starchy foods are unsuitable for those who are afflicted with
hyperchlorhydria or supersecretion of hydrochloric acid, as the excess
of acid prevents their digestion by neutralizing the alkali of the
intestines.
[Sidenote: Insalivation of starchy foods and meats]
The saliva secreted when nitrogenous food is eaten does not contain as
much ptyalin as that secreted when starchy food is consumed; for this
reason the thorough insalivation of starchy foods is much more important
than that of meat, milk, and eggs. Some authorities have recently
advised that people should not chew meat at all, but should swallow
it as do carnivorous animals. This advice, however, is not altogether
sound. In the first place, man is not a carnivorous animal, and the
gastric juice of the human stomach does not act as rapidly on flesh
foods as does the gastric juice of meat-eating animals, but if meat be
taken into the human stomach, either in large or in small quantities,
decomposition may take place before digestion has proceeded far enough
to prevent the action of micro-organisms.
[Sidenote: Mental influence upon digestive fluids]
The mental influence upon the secretion of digestive fluids may
originate from thought, or may be brought about reflexively by the
sight, or by the smell of food. All are familiar with the experience of
having one's mouth water at the sight of a particularly appetizing dish.
Many of us have undergone the same experience by merely thinking of some
particular food of which we are fond.
[Sidenote: Digestive juices vary with different foods]
Scientific investigation has shown that the secretion of saliva is
only an example of what takes place in the other digestive organs.
The experiments of the ingenious Russian scientist, heretofore
mentioned, prove that the act of tasting and of swallowing food was
the chief factor in determining the secretion of the juices from the
stomach-walls. In a series of operations upon dogs, performed by skilled
surgeons, certain interesting facts were observed. The esophagus was
severed and made to open externally so that the food swallowed did
not pass into the stomach. The secretion of gastric juice was then
determined in the case of different foods which were taken into the
dog's mouth and swallowed, but which did not reach the stomach. Not only
did this act of pretended feeding start a flow of gastric juice, but the
juice secreted in the case of different foods was especially adapted to
the particular food, according to the general principle which we have
already discussed.
These facts emphasize several important considerations regarding our
diet:
1 We should eat slowly and get the whole taste out of food by
thorough mastication, because taste largely controls the secretion
of the digestive fluid
2 We should not disguise our food by high seasoning
3 Foods that do not require the same digestive principles
should not be taken at the same meal
[Sidenote: "Fermentation" and "Putrefaction" compared]
Fermentation is the term generally applied to changes that take place in
such food substances as carbohydrates, due to the growth of bacteria,
while the term putrefaction is applied in a similar way to the changes
taking place in nitrogenous or proteid materials. Both of these chemical
changes are exceedingly harmful.
ABNORMAL CHEMICAL CHANGES IN THE DIGESTIVE ORGANS
[Sidenote: Bacteria chief causes of abnormal changes]
Under this heading we will consider the chemical changes which take
place in the human alimentary canal, which are not beneficial or
necessary to normal digestion. The cause of the most important abnormal
changes in the contents of the stomach and the intestines is the
presence of living micro-organisms called bacteria.
In the lesson entitled "Evolution of Man," a general survey of the
history of man's development from lower forms of life is given. In this
general work I do not elaborate extensively upon the method by which
evolution proceeds, but those who are acquainted with the writings of
Darwin, and other evolutionists, are familiar with the phrases "the
survival of the fittest," and "the struggle for existence."
[Sidenote: "Survival of the fittest" among bacteria]
As we commonly think of "the survival of the fittest" in animal life, we
picture the death-struggle of the captured animal, or the fight for food
in times of scarcity, or, if it be in the case of plants, the crowding
or the struggling for soil and sunlight. We can apply the same principle
to bacteria and to other microscopic forms of life.
Bacteria, while minute masses of unconscious protoplasm, are, by the
laws of growth and reproduction, struggling for existence just as truly
as are the more conspicuous forms of life.
Because of the invariable presence of greater or less quantities of
bacteria within the intestines of all ordinary animals, some scientists
insist that their presence is in some way necessarily related to the
life of the animal, and is probably beneficial.
[Sidenote: Experiments proving accumulation of bacteria]
New-born animals, however, are free from bacteria, and the bacterial
germs found in the more matured animal must, therefore, have been taken
into the alimentary canal with food. Ingenious scientists have taken
new-born guinea pigs, and have kept them in sterile or germ-proof
compartments, giving them filtered air to breathe, and absolutely
sterile food. These pigs lived and thrived through the experiment as did
their fellows outside the bacterial-proof dwelling. This is considered
good evidence that bacteria accumulate in the digestive organs of all
animals, not for a purpose connected with animal physiology, but because
in order to digest and to assimilate food, conditions are established
which are so nearly like those required for bacterial growth, that
bacteria are produced, or take advantage of the favorable conditions,
just as weeds, if given a chance, thrive in a cultivated field.
[Sidenote: Not all bacterial growth is harmful]
I have already referred to the antiseptic or germ-destroying properties
of the gastric juice, and to other secretions of the digestive organs.
This would suggest that the growth of bacteria is undesirable from the
standpoint of man's welfare. There are many species of bacteria growing
in the human intestines, hence we cannot say with certainty that all
this bacterial growth is harmful, as, in order to determine this, the
resulting waste-products of each particular species of bacteria would
need to be considered separately. We can, however, make the general
statement that bacteria are abnormal, or foreign to the human digestive
canal, and that their presence is detrimental to human welfare.
Micro-organisms give off various substances as waste-products of their
growth, dependent upon the species of bacteria, and the material in
which they are growing. Thus the waste-products of the yeast-plant are
carbon dioxid and alcohol.
[Sidenote: Waste-products of bacterial fermentation]
In the alimentary canal there exists an abundance of carbohydrate and
proteid substances which form excellent food material for numerous
species of bacteria. The substances produced by the growth of these
various kinds of bacteria are numerous. They include the gases, carbon
dioxid, hydrogen, hydrogen sulfid, marsh-gas or methane, and ammonia.
Butyric, lactic, and other acids, together with alcohol, are also
produced as a product of bacterial fermentation in the intestines.
Perhaps the most detrimental of all are the substances produced by the
bacterial putrefaction of proteids, of which indol and skatol are the
two most important.
[Sidenote: Solubility and distribution of bacterial waste-products]
Under ordinary conditions the bacteria themselves do not penetrate
the intestinal walls, and their evil influence would be confined to
mechanical disturbance of gas in the digestive organs, and to the
destruction of a portion of the nutritive material of food, were it not
for the fact that these harmful and poisonous waste-products I have
mentioned, are soluble, and hence pass through the intestinal walls with
the digested food material, into the blood, and are thus distributed
throughout the body.
It has been observed in the presence of intestinal congestion, where
the food lies in the intestines for an abnormally long period, that the
amount of these harmful nitrogenous decomposition products excreted by
the kidneys, is considerably increased, proving that these products have
circulated throughout the body.
[Sidenote: Causes of hardening of the arteries]
Arterio-sclerosis, or the hardening of the walls of the arteries, which
has for many years been recognized by scientists as one of the principal
causes of old age, comes from two causes:
(1) The over-consumption of starchy foods, especially of the
cereal group; and (2) by the continued presence, in the blood, of
small quantities of poisonous material which gradually destroys the
protoplasm of the arterial walls, and causes them to be replaced by
a degenerate form of tissue.
For example, alcohol and the poison of syphilis are prolific causes of
the hardening of the arteries. If the diet were balanced so as to avoid
excesses of starch and these toxic substances, the hardening of the
arteries would not take place.
[Sidenote: Overeating an ultimate cause of old age]
The poisons produced in the intestines by bacterial decomposition,
superinduced largely by overeating, are absorbed into the blood,
and undoubtedly their action is similar to the other poisons herein
mentioned. Thus they become a most potent factor in the cause of old age
and premature death, being practically universal among all civilized
tribes.
Numerous other disorders or dis-eases can be traced to this same general
cause, and the subject of the poisonous products of fermentation and
decomposition in the intestines will therefore be constantly referred to
throughout this work.
[Sidenote: The growth of bacteria decreased by scientific eating]
From the deductions that have been made it is clearly evident that any
system of feeding which will reduce the amount of bacterial growth in
the intestines, would be desirable and beneficial to mankind, while
foods and habits of life that increase the amount of such poisons are to
be guarded against as detrimental to both health and life.
[Sidenote: Overeating primary cause of fermentation]
Overeating is perhaps the greatest of all dietetic errors in bringing
about a condition which favors excessive intestinal fermentation.
Overeating causes stomach prolapsus, thus reducing its mixing or
peristaltic activity. This retards the process of emptying, called
digestion, which is the primary cause of fermentation. Under this
condition the antiseptic properties of the stomach-juices are reduced,
and the bacteria from the fermenting food is vastly increased. The
food, passing from the stomach in a fermenting state, produces gas in
the intestines, with the resultant ills that follow, such as vertigo,
dizziness, irregular heart action, and usually intestinal congestion or
constipation.
THE DECOMPOSITION OF FOOD
[Sidenote: Sugar destroys putrefying bacteria]
[Sidenote: Sour milk a preventive of intestinal putrefaction]
The putrefaction of proteids in the intestines may be reduced by the
liberal consumption of fresh sweet fruits. The preserving qualities of
sugar depend upon the fact that putrefying bacteria cannot live where
sugar is abundant. The beneficial effect of sweet fruits in reducing
bacterial decomposition in the intestines, is due to the presence of
relatively large quantities of sugar and of organic acids. Sour milk
is known to have a prohibitive influence upon putrefaction in the
alimentary canal. This is due to the milk-sugar, which has been changed
to lactic acid. This explains why clabbered milk, which contains a
considerable portion of sugar changed into lactic acid by the action
of souring bacteria, is especially beneficial in preventing intestinal
putrefaction. Professor Metchnikoff, of the Pasteur Institute of Paris,
became so enthusiastic upon this discovery that he proclaimed sour milk
to be a remedy for old age. While Metchnikoff's enthusiasm is perhaps
somewhat premature, yet the idea is worthy of much consideration.
[Sidenote: Proper feeding chief factor in reducing bacterial growth]
We do not need, however, to seek for any one specific remedy
against intestinal decomposition, but should study the selections,
combinations, and proportions of our food at each meal with the view of
reducing to the minimum the growth in the alimentary tract.
DIGESTIVE EXPERIMENTS
It is well known that only a portion of the food taken into the
alimentary canal is digested and absorbed into the circulation. It
is obvious that the undigested food plays no part in the process of
metabolism, therefore it is necessary to know the amount of the various
food elements that are digested. For this reason we will notice briefly
the method used in making digestive experiments.
[Sidenote: Determination of the amount of food the body uses]
The food eaten for a certain period of time is analyzed and weighed,
and the intestinal excreta, corresponding to the quantity of food under
study, is also weighed and chemically analyzed. The difference should
show the amount of food actually digested.
There are several serious difficulties in the way of making accurate
digestive experiments:
[Sidenote: Quantity of feces and time consumed in passing food through
the body]
1. It is very difficult to determine the quantity of feces
(intestinal excreta) that corresponds to a given quantity of food.
A digestive experiment is usually conducted for a period of about
one week, the man or animal being given a spoonful of lampblack at
the beginning and at the close of the experiment. The lampblack
being a finely powdered form of pure carbon, is insoluble in the
digestive juices, hence passes through the body without change,
thus blackening or marking the feces at the beginning and at the
end of the test period. The subject under experiment should be
given the same diet for a few days before and after the experiment,
so that the error due to the inability to accurately separate the
feces will be reduced to a minimum.
[Sidenote: Measuring the digestible portion of food]
2. The digestive juices, and especially the bile, pour
considerable material into the alimentary canal which cannot be
distinguished from the undigested elements of food. However, it
is fair to assume that when large quantities of body-proteids
are poured into the alimentary canal, and passed out with the
feces, this amount of matter is wasted by the body, hence should
be charged against the food which stimulated the secretion. For
example: If grain causes a large secretion of digestive enzyms,
it is no more than fair to say that grain is less digestible than
milk, which wastes less body-matter in its digestion.
[Sidenote: Certain foods may either aid or hinder digestion]
[Sidenote: The mono-diet system]
3. A further difficulty with the accuracy of digestive
experiments, and one to which in the past too little attention
has been paid, is the influence upon the digestibility of one
food by the presence of others. Some foods, such as fruits, aid
the digestion of other foods, while in many cases the presence
of a certain article seriously hinders the digestive process of
all. This emphasizes the great necessity for observing the laws
of chemical harmony in combining our food at meals, and it also
emphasizes the importance of limiting the diet to the fewest number
of things possible, which in the opinion of the writer will lead
inevitably to the mono-diet system, especially in curative or
remedial feeding.
[Sidenote: Difficulty of determining amount of undigested food]
From the standpoint of the above difficulties, all digestive experiments
thus far made are only approximately correct, and we are forced back
to the conclusion that if we obey the laws of nutrition, Nature will
give us her highest result expressed in endurance. If a single article
of diet is taken by a man who is accustomed to large quantities of a
highly varied bill of fare, the digestive process will not act in the
usual way. On the other hand, if several articles such as nuts, grains,
and milk are taken at one time, it will be impossible to determine what
percentage of the proteid or of the fat from the three various sources
remains undigested in the intestinal residue, hence no accurate results
can be shown regarding the digestibility of each particular food.
MECHANICS OF DIGESTION
[Sidenote: Condition of food influences chemical action]
Chemistry is not the only factor in the digestive function that is to be
taken into consideration. The mechanical condition of food, when it is
taken into the digestive organs, very greatly influences the chemical
process that takes place.
[Sidenote: Necessity for thorough mastication]
This involves the question of masticating or subdividing the food into
small particles. The greater the dissolving surface, the more rapidly
will solution take place. If the substance being dissolved is a firm
particle, the digestion or solution will take place only on the exterior
surface, and the interior of the particle, however small, will remain
practically unchanged. This is what occurs when food materials such as
grains and nuts are taken in an uncooked state, as mastication does not
dissolve them, but only divides them into small, distinct particles.
[Sidenote: Action of enzyms during digestion]
If, however, the grain be subjected to prolonged heating with water,
partial solution takes place. The entire mass becomes mushy and
permeated with moisture. When such a mass is brought in contact with
the digestive fluids, it mixes or disintegrates with the fluid, just
as molasses would mix with water. The result is that the whole mass of
material is subjected to the action of the digestive fluids at once,
with the result that the mass is passed from the stomach too quickly,
causing congestion in the small intestines, or the whole is arrested,
and fermentation and decomposition take place. In normal digestion,
the enzyms are continuously secreted for a period of several hours.
They begin work on the outside of the food particles, dissolving the
substances gradually. Thus the enzyms are continuously used up, and
the digestion proceeds slowly, but naturally, yet as fresh enzyms are
continuously being secreted to act on the newly exposed surfaces, active
and complete digestion is constantly taking place.
[Sidenote: Predigested "breakfast foods"]
The alleged predigestion of certain proprietary foods has neither
scientific basis nor virtue. That the juices of some fruits which are
already in the form of glucose, can be immediately absorbed into the
tissues without any digestive process, does not prove that the mushy
cooking, malting, and other forms of so-called predigestion are
beneficial. The so-called "predigested breakfast foods" are not and
cannot be prepared by any process for final digestion, but are in an
intermediate state between starch and glucose. They are composed of a
semi-soluble starch, gummy dextrin, and perhaps a little maltose which
has a tendency to disturb and to interfere with the normal process of
digestion.
[Sidenote: Comparative digestibility of cooked and uncooked starch]
I do not advocate the use of uncooked grain, but I wish to correct
a popular error in regard to the digestibility of uncooked cereal
starch. Nearly all works on physiology and diet make the statement
without reserve that raw starch is indigestible. This theory has been
established by putting samples of cooked and uncooked starch into two
test tubes, and treating them with some digestive enzym. The cooked
starch, being soluble, is all exposed to the digestive enzyms at one
time, and started on its way through the numerous changes in the
complex chemical process of changing starch into glucose, while in the
sample of uncooked starch, the digestive enzym attacks the particles
from the outside, and slowly digests or eats off the exterior of the
starch grains. After a given length of time the chemist adds iodin to
the two test tubes. With starch, iodin gives a blue color. In the test
tube containing the cooked starch, all of which has undergone a certain
amount of digestion, no blue color is discerned, for no pure starch is
left, while in the other tube, in which some of the particles remain
unchanged, owing to the fact that Nature does all her work slowly, a
blue reaction is of course obtained, and the chemist proclaims that
uncooked starch is indigestible.
[Sidenote: Government experiments with cooked and uncooked grains]
At one of the United States Experiment Stations in the state of Kansas,
a comparison of two diets, consisting chiefly of several varieties of
grains, was recently made. The diets were alike in every respect with
the exception that in one instance all the grains were boiled for two
hours, while in the other case they were taken in an uncooked state.
In the case of the uncooked grains, no starch whatever passed through
the body in an undigested form. In the case of the cooked grains, the
same results were found; that is, no starch was found in the intestinal
residue. Other substances, however, remaining undigested in the cooked
diet, were much in excess of that in the uncooked, yet no starch was
present. In the case of cooked grains, the digestive processes may
start with more rapidity than in uncooked grains, yet they are not
thoroughly completed, and various decomposition products occur, as well
as undigested proteid, which is not likely to occur with foods taken in
their natural state.
[Sidenote: Uncooked starch harmless]
Moreover, if uncooked starch be taken in excess of the digestive
capacity, and passed through the body wholly unchanged, no harm results.
The starch grain, in its unchanged state, is a fine, white glistening
granule, and its presence in the digestive tract would have no harmful
effect upon the body functions. Without solution, no material can have
any effect upon the physiological processes, except by irritating the
mucous surfaces of the digestive organs; in the latter respect, starch
granules are harmless.
[Sidenote: Condition in which food should enter digestive organs]
With the exception of articles that are in solution, the condition in
which all foods should enter the digestive organs is in finely divided,
yet distinct particles, and not in pasty or gummy masses. In this latter
form "bolting" is encouraged, and mastication greatly discouraged.
THE MUSCULAR MOVEMENT OF DIGESTIVE ORGANS
[Sidenote: Peristaltic movement in alimentary canal]
Another point to be considered in digestion, and which may well be
classed under the mechanics of digestion, is the muscular action or
peristalsis of the alimentary tract. The best example is the swallowing
action observed in the throat of a horse, or of a cow, when drinking. At
each swallow, what appears to be a lump goes down the throat. This is a
wave-like relaxation of the muscular walls of the esophagus, followed
closely by a muscular contraction. This is the action that takes place
in the intestinal tract, and that which Nature employs to move the
contents along toward the final point of excretion.
[Sidenote: X-ray examination of peristalsis]
A very fascinating and scientific demonstration may be performed in the
following manner: A cat may be given food mixed with some such substance
as bismuth subnitrate, which is opaque to X-rays. Upon placing the
animal under an X-ray during digestion, this peculiar peristaltic motion
can be observed, one "swallow" passing rapidly after another down the
alimentary tract.
This method of investigation has also shown that peristaltic action
stops immediately in the case of fright, or anger, but is shown to
proceed with regularity during sleep, contrary to the antiquated idea
that digestion ceases when sleep begins.
[Sidenote: Milk for relieving constipation]
Peristaltic action in the lower parts of the alimentary canal is
stimulated by taking food into the stomach. This explains the laxative
action of such foods as fruits, or, sometimes, milk, taken at frequent
intervals. When all other methods fail, constipation can oftentimes
be relieved by taking a glass of milk every thirty minutes until four
glasses have been consumed.
[Sidenote: Moisture and peristaltic action]
The longer food remains in the intestines, the more completely is the
water absorbed from the residue. The object to be obtained in relieving
constipation is to increase the moisture and the peristaltic action.
Whatever will accomplish these things will relieve and perhaps cure
intestinal congestion.
The subject of intestinal congestion and purgative medicines will be
discussed at length in Lessons IX and XI, Vol. II, p. 375 and p. 436,
respectively.
LESSON VI
CHEMISTRY OF METABOLISM
[Sidenote: Meaning of metabolism]
Metabolism is a word used to describe all processes that take place
within the body from the time food is absorbed from the digestive
organs until it is passed out of the body through some of the excretory
channels. To be more accurate, it means the sum of both the anabolic,
or constructive, and the catabolic, or destructive, processes that
continually go on in the animal body.
[Sidenote: Distinction between anabolism and catabolism]
The process of metabolism is chiefly one of tearing apart, or of
breaking down, complex chemical substances into simpler forms of matter.
Formerly, all processes in animal life were considered to be those
of tearing down, or of simplifying, chemical compounds; while plant
life was considered to be chiefly the process of building up complex
substances from simpler forms of matter. This distinction, however, is
rather general with many exceptions. The two terms, "anabolism" and
"catabolism" are sometimes used to distinguish between the processes of
building up complex chemical compounds, and the oxidizing or tearing
down of such compounds by effort or activity. Thus, the formation of
muscular tissue from the digested proteid materials would be a process
of anabolism, or construction, while the conversion of glucose in the
muscle-cells, into carbon dioxid and water would be an example of
catabolism, or destruction.
[Sidenote: Catabolism a process of oxidation]
The process of catabolism is, in general, one of oxidation; that
is, oxygen is added to the chemical compounds taken from the food
we eat, forming simpler substances which are excreted from the body
as waste-products. Oxidized carbon in the body forms carbon dioxid;
hydrogen is oxidized into the form of water, while nitrogen leaves the
body in the more complex and incompletely oxidized substance known
as urea, the chemical formula of which is COH₄N₂. A small portion of
nitrogen leaves the body in the form of uric acid, C₅H₄N₄O₃.
[Sidenote: Why muscular work produces warmth]
The process of anabolism usually absorbs energy or heat from the
surrounding material, while catabolism produces heat as a result of
oxidation, as do ordinary fuels. This explains why muscular work warms
the body.
We may study metabolism best by considering the two purposes food serves
in the animal body, as follows:
FIRST--THE BUILDING OF ACTUAL BODY-TISSUE
Every atom composing the human body is constructed from food. The
number and the proportion of the various chemical elements composing
the body are well known, and were it not for the fact that the body is
constantly casting out old cells and waste-products, the problem of
nutrition would resolve itself into the simple process of supplying the
body with the materials needed for growth.
[Sidenote: Formation of new tissue and destruction of old]
We could analyze an adult man and a new-born infant, and know that
the infant, in order to reach maturity, would need to add to its body
so many pounds of oxygen, carbon, sulfur, iron, etc. The problem of
nutrition, however, is more complex. Not only must we consider the
formation of new tissue, but we must also allow for the rebuilding of
the old, and for all those processes of vital activity that involve the
consumption of food material and the destruction of body-tissue. Nor can
this allowance be accurately proportioned from the analysis of the body,
because the various elements composing it do not change with equal
rapidity. Thus, a man in a harvest field might pass through his blood in
one day ten or fifteen pounds of oxygen (in the form of water and carbon
dioxid), which would amount to ten per cent of the oxygen contained in
his body, but if he should take calcium or fluorin to the extent of
ten per cent of that contained in the body, death from poisoning would
speedily ensue.
We can better understand the use of foods and the process they undergo
in building the body by considering separately each class of food
material from the time it is absorbed from the alimentary tract until
it is excreted from the bowels, or from the lungs and the kidneys, or
deposited in the body as bone, fat, or tissue.
SECOND--THE GENERATION OF HEAT AND ENERGY
The second function, or rather group of functions to be considered in
the study of metabolism is the generation of heat and energy. If the
reader will recall what was said in Lesson II, regarding the production
of heat by the process of oxidation, he can more clearly comprehend the
method by which heat is produced in the animal body. However, as heat
is only one form or expression of energy, these two subjects--heat and
energy--should be considered together.
[Sidenote: Heat and energy produced by oxidation]
The production of heat and energy in the body occurs almost entirely
through the oxidation of food. All three classes of foods, namely
proteids, carbohydrates, and fats can be oxidized to produce heat.
[Sidenote: Heat, a measure of energy]
Energy may be mechanical, chemical, electrical, or thermal. The
conservation of energy, which is one of the fundamental laws of science,
teaches that no energy can be lost, but can only be changed into other
forms. This being true, and because all energy can be changed into heat,
we use heat as a measure of energy.
[Sidenote: The "calory," a unit of heat]
The unit of heat, and consequently of energy, that is used by scientists
is the "calory," which is the amount of heat required to raise the
temperature of one thousand grams of water one degree on the centigrade
thermometer scale. The energy in food is measured in calories, as will
be learned from the explanation given in the lesson entitled "Vieno
System of Food Measurement."
[Sidenote: Liberation of energy through metabolism]
The Vieno is merely a unit especially convenient in measuring the energy
in food. In order that this energy may be drawn upon or liberated in
the body, it is necessary for the food to pass through the process of
metabolism, as heretofore described.
THE MEASURE OF HUMAN ENERGY
Food may be considered as a store-house of latent or potential energy.
[Sidenote: Intake and outgo of energy accurately determined]
Because of the law, the conservation of energy, which shows that no
energy in the universe can be lost, it is possible to study, with great
accuracy, the energy produced in, and given off by, the human body.
The method by which energy is measured in accurate scientific
experiments is by means of a device called the respiratory calorimeter.
[Sidenote: How energy is measured]
[Sidenote: Energy yielded from one gram each of proteids, carbohydrates
and fats]
This device is a small room, the walls of which are impervious to the
transmission of both heat and air. In this room a man or an animal may
be kept for a period of several days. The air breathed, the food eaten,
the body-heat given off, the waste-products excreted, and the mechanical
work done, are all measured with the greatest scientific accuracy. Many
interesting results have been obtained from the investigations conducted
with this wonderful scientific device. These experiments will not be
given in detail in this work, but it might be remarked that experiments
within the respiratory calorimeter have proved absolutely that the law
of "the conservation of energy" works in the human body in the same
manner as in the scientist's laboratory. Moreover, such experiments
have confirmed the results of the oxidation of various foods in the
laboratory, and have given us data from which to compute the stored
energy in various food substances. It has thus been found that the
amount of energy yielded to the body from one gram of proteid is 4.1
calories, and from one gram of carbohydrates 4.1 calories, while one
gram of fat oxidized in the body yields 9.3 calories, which is more than
twice that yielded by the proteids and the carbohydrates.
[Sidenote: Simple method of finding number of calories in any food]
Since it has been proved that the laws established in the laboratory
also apply to the human body, it is not necessary to conduct expensive
experiments upon the human subject in order to ascertain the amount of
energy in some new food. The food may be analyzed chemically, and the
energy computed according to the above figures, or a sample of the food
may be burned with an oxidizing agent in the laboratory, and the heat
measured. This latter process consists simply of oxidizing a gram of
the food in a closed steel cylinder which is immersed in a known amount
of water at a known temperature. The increase in the temperature of the
water, multiplied by the weight of the water in grams, gives the number
of calories contained in the substance tested.
METABOLISM OF CARBOHYDRATES
[Sidenote: Products formed in the body from digested carbohydrates]
The products produced by the digestion of carbohydrates are absorbed
from the alimentary canal in the form of glucose and smaller quantities
of levulose, and acetic, butyric and lactic acids. This glucose passes
into the blood-vessels of the intestines. These blood-vessels unite to
form the portal vein which supplies blood to the liver.
[Sidenote: Conversion of glucose into glycogen]
[Sidenote: Percentage of glucose in blood]
The chief function of the liver is to regulate the sugar contained in
the blood. The liver converts this glucose into glycogen and also acts
as a reservoir in which carbohydrates are stored in the form of glycogen
until needed by the body. From this glycogen, glucose, or blood-sugar,
is again produced when the consumption from the circulation is greater
than the supply. Moreover, the liver possesses the power to produce
glucose when no carbohydrates are eaten, as glucose can be produced from
proteids. The percentage of glucose in the blood remains, or should
remain about level, averaging .15 of 1 per cent. It may seem odd at
first that the quantity of glucose in the blood remains so nearly level,
when the quantity absorbed from the digestive organs, and that utilized
in work, is so variable. The control of sugar in the blood is of very
great importance in the body-metabolism or life-processes.
[Sidenote: Uses of glucose in the body]
The chief use of glucose, and of other forms of digested carbohydrates
is in the formation of heat and energy. Glucose is oxidized chiefly
in the muscles, producing carbon dioxid, water, and some lactic acid.
Another function of glucose in the blood is to build up or form fat. Fat
is a form of stored food which is not so readily available for use as
are glycogen and glucose.
To use a homely figure of comparison, the energy-producing substances
of the human body--glucose, glycogen, and fat--may be compared to the
movement of merchandise in ordinary commerce. We could say that the
glucose of the blood is as merchandise in the hands of the people,
ready to be consumed. The glycogen of the liver would represent goods
in the hands of the retailer, while the fat which is stored in larger
quantities would be represented by merchandise in warehouses.
[Sidenote: Fat produced from carbohydrates]
Many interesting experiments have been conducted to prove that fat can
be produced from carbohydrates. For instance, during a given period of
time a pig was fed daily upon food containing half a pound of fat, and
gained during the period nine pounds of fat. Such facts prove beyond all
possibility of doubt that carbohydrates are converted into fat in the
animal body.
METABOLISM OF FAT
Fat, when absorbed from the digestive tract, is in the form of fatty
acids and glycerin, but immediately recombines into its original form
after it has passed through the intestinal walls. This fat then enters
the lacteals, which unite to form the thoracic duct. This duct or tube
empties its contents into one of the large veins near the heart, whence
it is distributed throughout the body. The fat of the blood is not
regulated to a definite amount, like the sugar content. After a meal,
very heavy in fat, the blood for a time is whitish in appearance, due to
the numerous minute globules of fat taken into the circulation.
[Sidenote: Body-fat may be absorbed directly from food]
The fat of the body may be deposited directly from food-fat. This can
be verified if an animal that has been starved until its own body has
been greatly reduced, be fed upon some particular form of fat. The fat
immediately deposited will then have the peculiar characteristics of the
fat taken with the food. Thus a starved dog that has been given a heavy
diet of tallow will deposit fat which will contain a large quantity of
stearin and palmitin, and consequently have a higher melting point than
normal dog fat. Ordinary animal fat, as has been shown in Lesson IV, is
composed of various fats, each of which is a distinct chemical compound.
[Sidenote: Human fat not identical with food-fat]
The distinction between tallow, lard, olive-oil, and human fat, is
chiefly due to the various portions of stearin, and olein, which
composes the mixed fat. In normal cases, where fat is deposited at
the usual rate, the body-fat is of uniform composition regardless of
the food-fats. The reason human fat is not identical with food-fat is
because the body has selective power in depositing these fats. Thus,
if the sole source of fat which a man takes in his food is tallow, the
fat-depositing cells in the human body would refuse a certain proportion
of the stearin, depositing a larger percentage of olein, thus giving
a softer or more liquid fat than that which was supplied in the food.
The excess of stearin would be consumed in the production of heat and
muscular energy.
[Sidenote: Why exercise reduces obesity]
When the consumption of glucose in the muscles becomes greater than
the supply available in the blood, and from the glycogen of the liver,
body-fat must be consumed. This explains why exercise reduces obesity.
The method of preventing, or of curing, obesity, is a double process:
1 The diet is selected and proportioned so as to reduce the
amount of ingested fat
2 Exercises are prescribed to consume the fat that has
accumulated
[Sidenote: Fat, the chief source of energy]
Of all food materials, fat is the least changed by digestion, and has no
particular function in the life-processes except the storing of energy.
More body-energy can be stored in a pound of body-fat than in any other
form.
From these deductions it is evident that carbohydrates and fats perform
very similar functions within the body, and can, in a large measure,
replace each other as a source of heat and muscular energy.
METABOLISM OF PROTEIDS
[Sidenote: Importance of proteid or nitrogenous foods]
Owing to the fact that the tissues of the normal body are constructed
chiefly from proteids, the metabolism of proteids or nitrogenous foods
is of very great importance. When we realize the fact that muscle,
blood, brain, nerves, cartilage, tendons, the various internal organs
and the tougher material of the skeleton are only various forms of
proteid material, and must contain their proportions of available
or organic nitrogen, we can understand why nitrogenous foods form a
distinct class that must be considered by themselves. Only the mineral
deposits of the bones and the teeth, and the globules of fat that are
deposited as a source of stored energy represent the nitrogen-free class
of substances within the animal body.
THE USE OF PROTEIDS IN THE BODY
[Sidenote: Proteids as tissue-builders]
The first use Nature makes of proteids in the body is in the actual
adding to or increasing of body-tissue. When an emaciated young man from
the city goes to work on a farm and gains twenty pounds, the cells of
his muscles have actually increased in size and number. This requires
proteids, which can be obtained only from the nitrogenous material in
food. The growth during early life is due to an actual increase in the
size of all the organs of the body, and is merely an accumulation of
proteid substance.
[Sidenote: Proteids form the nitrogenous part of the body]
The second use of proteids, and the one which, in matured life, is of
more importance than those already referred to, is in the formation
of the various nitrogenous products which are produced in connection
with the different processes of the body and which are destroyed by
the function of life. For example, the pepsin of the gastric juice is
a nitrogenous substance which can be formed only from proteids. All
digestive enzyms and other substances in the muscles, nerves, and in
the various organs throughout the body are of a nitrogenous nature,
and in their formation and use a certain amount of proteid material is
consumed. When the digestive enzyms are formed from proteids, they
consume more than their own weight of proteid material.
[Sidenote: Proteids replace worn-out cells]
The third form in which proteids may be consumed in the body is in
the actual replacement of worn-out cells. The skin, the hair, and the
mucous or lining membranes of the body-cavities are constantly being
cast off on the external surface, new cells being formed underneath.
When cells within the interior of the body have become injured, or have
passed their usefulness, they are removed by the phagocytes or white
blood-corpuscles, and must be replaced by other cells. In the case of
bacterial infections, as tumors, boils, or contagious dis-eases, the
bacteria feed upon the proteids of the blood. The white blood corpuscles
are destroyed in the conflict, or effort to remove the intruders, and
all these substances must be replaced by proteids from food.
THE ACTION AND THE COMPOSITION OF PROTEIDS
[Sidenote: Determination of income and outgo of nitrogen]
The gain or loss of body-proteids is indicated by the gain or loss
of nitrogen. The income of nitrogen can be ascertained by analyzing
the food. The outgo of nitrogen is computed by analyzing the products
excreted from the body. If the body at the beginning and at the end of
an experimental period is carefully watched, and the income and the
outgo of nitrogen determined, we can compute the amount of gain in the
body that is nitrogenous tissue. The other gain or loss of body-weight
must be fat. These calculations cannot be made exact, owing to the
amount of food and water that may be in the digestive organs at the time
the various weighings are made.
[Sidenote: Why proteids are converted into peptones]
We have learned that in the digestive tract foods are converted into a
soluble form of proteid known as peptone. The purpose of this conversion
and the fine subdivisions of food produced by the various digestive
juices are to reduce it to a form which will readily pass through the
walls of the alimentary canal.
[Sidenote: Nitrogen and urea]
This is all that was known about proteid metabolism until within very
recent years. The older scientists followed proteid digestion until the
soluble peptone stage was reached, at which point all track was lost of
the chemical changes and processes until the nitrogen was again excreted
by the kidneys in the form of urea.
No scientist attempted to explain how the radically different proteids,
such as egg-albumin, milk-casein, and wheat-glutin could appear in the
body as blood-globulin, brain-lecithin, or as a myosis of the muscles.
The history of all these investigations cannot be fully explained here,
but the discussion must be confined to that which actually takes place
in the metabolism of proteids.
[Sidenote: Composition of proteids]
Proteids, as the student will remember, contain carbon, hydrogen,
oxygen, and nitrogen, and sometimes small quantities of sulfur,
phosphorus, or iron. These forms of proteids are now known to be
chemically changed, by the digestive enzyms of the intestines, into
simpler compounds containing these same elements.
[Sidenote: How proteids may form body-fats]
These simple nitrogenous substances pass into the liver. Just as the
liver regulates the supply of blood sugar, so it regulates the supply of
nitrogenous compounds in the blood. A certain amount of proteid-forming
material is passed through the liver, and goes on to perform the various
functions for which proteid is utilized in the body. All nitrogenous
material in excess of the amount required by the body is secreted by
the liver, and the nitrogen, together with a portion of the carbon,
hydrogen, and oxygen, is split off, forming urea, which is excreted by
the kidneys. The remainder of the proteid substance, having been robbed
of its nitrogen, is now essentially the same as carbohydrates, and goes
to form glucose or blood-sugar, which may in turn form body-fats.
[Sidenote: Excess of proteids harmful]
In the light of this explanation, we can understand several things
already mentioned. It has been stated that proteid is the most essential
food material of the body because it alone contains the nitrogenous
compounds from which the body-tissues, and the chemical enzyms which
control all living processes, can be constructed. But we now see that
as important as is a supply of proteid materials, any excess above the
body-needs is immediately turned into glucose and urea. The glucose,
though useful to the body, could be taken in a simpler and less
expensive form, while the urea is a waste-product, harmful to life, and
must be immediately excreted by the kidneys.
The nitrogen that is actually used in the body serves a different
purpose from that which is split off from the excessive proteid taken
as food. The food proteid is simply split by the chemical addition of
water, much the same as starch and other carbohydrates are changed into
glucose. The proteid that is really used by the body is oxidized, and is
excreted by the kidneys chiefly in the form of creatinin and uric acid.
FOOD STANDARDS
[Sidenote: Incorrect interpretation of scientific data]
The term "dietary standard," as it has been applied in the past, means
the quantity of the several nutrients that should be taken by the human
body under its varying conditions. During the past twenty-five years,
many investigations have been made in this country, Europe, and Japan,
regarding the amount of foods consumed by various groups of people. All
the facts gathered, which include more or less accurate records of the
foods eaten by many thousands of individuals under all circumstances
and conditions of life, are invaluable scientific data, but the
interpretation that has been placed upon these interesting observations
is one of the most conspicuous blunders made by the scientific world.
Whether this criticism should fall wholly upon the men of science, who
made these investigations, or upon the people who misinterpreted their
meaning, is perhaps an open question; but the fact remains that from the
general teachings in physiologies, and from popular bulletins published
by the National Government, very incorrect ideas have been widely spread
respecting the amount of food required to maintain life and health.
[Sidenote: Data of foods consumed daily by various people]
In order to give the reader some idea of the results obtained, when
data is kept each twenty-four hours, of the amount of food consumed
by various people on the conventional diets of civilization, I will
select at random some of the results that have been recorded in these
investigations, and will give in the Vieno System the approximate
results. (See "Vieno System of Food Measurement," Vol. III, p. 639):
_Decigrams_
_Nitrogen_
_Vienos Consumed_
California Football Team 66 375
New England Rowing Club 40 255
Wealthy Class in American Cities 30 250
U. S. Army Rations. 37 200
Farmers, Eastern U. S. 34 160
Skilled laborers, U. S. Cities. 40 220
Alabama Negroes 34 145
Japanese Peasants 20 100
[Sidenote: Atwater's Government Standards]
From such records Government standards have been roughly approximated.
The standards published by the Government, computed by Prof. Atwater,
and commonly known as the Atwater standards, are as follows, expressed
in vienos:
_Decigrams_
_Nitrogen_
_Vienos Consumed_
Man at hard muscular work 55 280
Man at hard work 41½ 240
Man at moderate work 34 200
Man at light muscular work 30½ 180
Man of sedentary habits 27 160
The Atwater standard for women is estimated to be four-fifths of the
amount of food required for a man under similar conditions.
[Sidenote: Faulty standards due to inexperience]
It is generally recognized by investigators that these so-called
standards are faulty, but by mutual agreement it seems that they have
been accepted as the best that could be given. They lack accuracy
because the men who prepared them lacked experience. Accuracy can
come only from experience gained in the practical work; that is, in
prescribing food, and combinations of food, for people under all the
varying conditions of age, climate, and activity, and having these
people report, at stated periods, the results of their dietetic
prescriptions.
[Sidenote: Importance of correct dietary standards]
The average person eats what is set before him and asks no question
about nitrogen and energy; nevertheless, advice so universally
distributed as the Government Dietary Standards must exert much
influence and have a considerable effect upon the habits of the people.
Obviously the correctness of these standards is of vital importance to
the health and the welfare of the nation.
[Sidenote: What a dietary standard should contain]
A dietary standard should tell the quantity and the proportion of food
required to keep the human body in its very best working state. The
great error committed by the man who planned the above-named standards
has been that he assumed that an average of what a man _does_ eat is a
criterion of what he _should_ eat in order to maintain the best mental
and physical condition. A greater error could not have been made. _Our
feeding instincts have been lost in the chaos of civilization._ Both our
appetite and our food have been perverted. We have been trained to want
or to crave intoxicants, stimulants and sedatives; we have learned to
relish things that have no food value, and we have grown to dislike the
best food that nature produces, and to accept many of her worst. Dietary
standards, therefore, made up from the conventional eating habits of
the people, merely endorse their errors and pass them on to future
generations. The work, therefore, of the true scientist is to point out
these errors and to prescribe a remedy.
[Sidenote: We are creatures of many (bad) habits]
Man is a creature of habits, and civilized man is a creature of a great
many bad habits. The argument that the average amount of food eaten is
the amount that should be eaten falls under suspicion at once when we
consider the fact that by a similar line of reasoning we could prove
that the use of tobacco is necessary because the majority of men use it,
or that slender waists are necessary to good social standing because a
few million women so consider them.
[Sidenote: American prosperity not due to rich diet]
The idea has been spread far and wide that the diet of the American
working man, which is the richest in proteid of any race in the world,
is responsible for the greater economic thrift of the American people.
It is a matter of history that rich diet is always associated with
prosperity, but the theory that the diet is the cause of the prosperity
is an egregious error. Meat and rich foods gain a hold upon the appetite
as do alcohol and narcotics. When nations or cities become wealthy,
intemperance in eating is the usual result, but this in nowise indicates
that a heavy consumption of food is the cause of a nation's greatness.
History recites many instances of the rise and growth of a people to
power and prosperity, together with the consequent adoption of excessive
and luxurious habits of eating and drinking, only to be followed by
physical deterioration.
[Sidenote: Excessive food a waste of energy]
It is not the quantity of food that is eaten, but the quantity of food
that will give the greatest vitality and capacity to do things, that
should determine our dietary standards. It is reasonable to assume that
this amount would be the least quantity that would maintain activity
without using up the food material stored in the body. All food taken
in excess of the amount actually required must be cast from the body at
a tremendous expense of energy. To do a given amount of work, or to add
one pound of muscular tissue to the body, requires a definite quantity
of energy-yielding or tissue-building material, but if more food is
taken than the body can use, the excess ferments in the stomach and in
the alimentary tract, producing poisonous products which are absorbed
into the blood. These poisonous products cause a great number of human
ills. The process of eliminating these poisons we call "dis-ease."
[Sidenote: Former dietary standards cut in half]
The assumption that the correct amount of food that should be taken by
the body is the least quantity that will maintain normal body-functions,
has been amply proved by recent scientific investigations to be correct.
Many years of experience on the part of the writer have shown that to
make food remedial and curative, the old dietary standards must be,
roughly speaking, cut in half.
TRUE FOOD REQUIREMENTS
[Sidenote: Quantity of food required for various occupations]
The degree of energy required by the body depends very largely upon
the amount of work or activity it undergoes, hence the amount of food
required to supply this activity cannot be accurately prescribed
when the degree of required energy is unknown. However, there is a
certain amount of work performed by the beating of the heart and in
the maintenance of body-heat which can be fairly well estimated. The
quantity of energy-yielding food required, each twenty-four hours, for
the maintenance of the activities of life is about one vieno for every
ten pounds of body-weight. For a man at steady muscular work, such as
a carpenter or a farmer, this quantity should be about doubled. The
quantity required by a man of sedentary habits, but who takes regular
exercise for an hour or two each day, is about half way between these
two amounts. Thus, a man weighing one hundred forty pounds would require
one and one-half vienos for each ten pounds, or twenty-one vienos of
food each day. These weights apply only to people of normal flesh, who
desire neither to gain nor to lose.
The fact that either fat or carbohydrates can be used as a source of
muscular energy may be taken advantage of in prescribing dietaries
for persons whose digestive organs are so impaired that they cannot
digest a normal quantity of either of these nutrients, but who could
digest a small quantity of either. This does not mean, however,
that the proportion of fat and of carbohydrates in the food can be
disregarded. The digestive processes involved are radically different,
hence a suitable proportion of carbohydrates and fats should always be
maintained.
[Sidenote: Proportion of fat required under ordinary conditions]
With a view to guiding in a general way those who wish to adopt a
standard of diet for ordinary use, and who consult tables in which
fats and carbohydrates are listed separately, I might state that
the fat should form about one-eighth the total source of energy, or
one-sixteenth the weight of all water-free (solid) food eaten.
[Sidenote: Fallacy of lean meat producing muscle]
Until forty years ago the idea was held by scientists, and is still a
matter of popular belief, that nitrogenous foods are the sole source of
all muscular energy. This is quite a natural assumption. Lean meat is
muscle. If a man eats the muscle of another animal, by the primitive
process of reasoning, he should acquire muscle. This belief among people
who are not acquainted with physiological chemistry is almost universal,
while the facts are, the man who eats the muscle of an ox for the
purpose of adding strength to his own biceps is acting no more wisely
than the college boy who takes calf's brain for breakfast the day before
examination.
[Sidenote: Nitrogenous foods not a source of muscular energy]
The fact that nitrogenous foods are not a source of muscular energy has
been repeatedly proved by experiments on man and animals too numerous
to relate here. The sugar and the fat in the blood are taken into
the muscle-cells, and there unite with the oxygen brought from the
lungs, producing energy. When the body is fed upon proteids lacking a
sufficient quantity of other food elements, a portion of this proteid
is converted into glucose or sugar, which maintains body-heat and
energy. This is what happens in the case of carnivorous animals that
have excretory organs especially adapted to the converting and the
eliminating of useless or surplus products.
[Sidenote: Small amount of proteid matter required by animals]
It has been proved that dogs are capable of living for an indefinite
period of time upon a diet containing only a small proportion of
proteid matter, while maintaining health and increasing in weight.
Thus we see that even carnivorous animals require, for the maintenance
of the body-functions, a comparatively small amount of nitrogenous
material. Their strength and heat-forming elements can be secured
from carbohydrates and fats, probably to their actual benefit. It is
interesting to note, however, that dogs as a general rule cannot live
and thrive on a vegetable diet; a certain amount of animal proteids
seems indispensable. The same principle applies to other carnivorous
animals. Even ducks and chickens need a small percentage of animal
proteids in order to properly thrive and develop.
[Sidenote: Conditions governing quantity of nitrogen]
In order to maintain good health, every person requires a certain
amount of nitrogen, the quantity being governed by activity, exposure,
age, and temperature of environment. The growing youth needs nitrogen to
supply material for the tissue growth of his body; an emaciated person
who wishes to increase weight, a person recovering from illness, or a
man who is constantly performing strenuous work, would all require a
generous quantity of nitrogenous food.
[Sidenote: Lowest daily amount of nitrogen required]
The lowest possible nitrogen requirement for one of normal weight has
been determined by various methods to be from 40 to 60 decigrams per
day. This quantity, however, is the actual amount that is used in
the body-processes, and should be increased according to activity or
exposure to the open air.
[Sidenote: Amount of nitrogen required by the body]
From the results of numerous experiments under normal activity, the
quantity of nitrogenous food estimated to maintain the best bodily
condition is about three-fourths of a decigram for each pound of
body-weight; less than one-half of a decigram per pound of body-weight
would cause nitrogen starvation, while more than one decigram per pound,
except in the cases just mentioned, would result only in thrusting
needless work upon the liver and the kidneys, whose duties are to guard
the body against the results of incorrect eating. There are certain
conditions under which this amount of nitrogen may be exceeded in order
to gain definite and specific purposes, but in such cases the nature of
the proteid is of great importance. In certain occupations, for instance
sedative labor, the most soluble proteids, such as egg albumin (white of
eggs), milk, and green peas and beans should be selected; while in cases
of heavy manual labor, the heavier proteids, such as nuts, cheese, dried
legumes, fish and fowl should be selected.
LESSON VII
FOODS OF ANIMAL ORIGIN
An intelligent discussion of this lesson leads us directly into a
subject commonly known as "vegetarianism." The question whether man
should eat the flesh of animals is especially fascinating for those
who give attention to the food they eat. There are many standpoints,
however, from which the subject of vegetarianism may be discussed.
[Sidenote: Influence of religion on man's food]
In the first place, nearly all religious teachings that have wielded
such a powerful influence over the civilization and destiny of men,
have laid some restrictions upon the flesh-eating habit. Some religions
require man to refrain from all animal products, while others interdict
only the flesh of certain animals. Coupled with man's world-wide search
for food, these religious teachings have played a conspicuous part in
the question of human nutrition.
[Sidenote: Vegetarianism from animal's standpoint]
The second phase of the question that merits attention is the moral
side, or vegetarianism from the animal's standpoint; in other words, the
cruelty involved in the slaughter of our dumb friends and helpers, for
whose presence here we are largely responsible. That the practises and
customs which train humanity in cruelty toward animal life, are to be
discouraged, cannot well be disputed, but this phase of vegetarianism is
one which is somewhat without the realm of applied food chemistry, hence
is mentioned only as a factor in the general discussion.
[Sidenote: Vegetarianism from standpoint of scientific living]
I will now consider vegetarianism from the standpoint of true food
science, or the welfare of the physical man. It will be observed that in
the lesson entitled "Evolution of Man," one of the first considerations
taken up is the scientific discussion of man's natural adaptation to the
use of flesh foods. By natural adaptation I mean Nature's evolutionary
plan of fitting the physiological organism to the food man is able to
procure. The organism of man will, to a certain extent, adapt itself to
a given diet within the brief period of one generation, just as, in the
long ages of evolution, the digestive organs of any species of animal
become adapted to such diet as may be procured. Thus it is of especial
importance for us to know the diet of primitive man at a time before his
intellectual resourcefulness made it possible for him to gather his bill
of fare from the four corners of the earth.
[Sidenote: Primitive diet of man]
The diet of our related anthropoid apes, of every primitive savage
tribe, and of our ancestors, indications of which have been found
in fossils and caves--all three throw light upon the subject. The
consensus of these various studies indicates that the original or
natural diet of man was one drawn chiefly from the vegetable kingdom,
but not entirely so. Fruits, nuts, green vegetables, edible foliage,
tubers or roots were all included in man's primitive diet. The foods
of animal origin were varied, and consisted of such articles as birds,
eggs, shell-fish, many insects, and other forms of lower animal life, of
which our modern habit of eating frogs' legs, eels, escargots (snails),
etc., is merely an inheritance.
[Sidenote: Why flesh-eating is unnecessary]
Since the digestive, the assimilative, and the excretory organs of man
have been constructed from, and adapted to, the use of vegetables, it
is obvious that the flesh of animals is unnecessary, especially in view
of the fact that there is nothing in flesh that cannot be secured from
the vegetable world in its best and purest form. Man's primitive diet
does not prove that he is by nature a vegetarian, as is the cow, and
therefore entirely unsuited to digest any material of animal origin. The
anatomy of man's teeth and of his digestive organs, however, indicates
that he is by nature a vegetarian, and that his digestive organs are
prepared to dissolve and to assimilate a diet that is somewhat more
bulky than that of carnivorous animals, but, on the other hand, less
bulky than the diet of animals which subsist wholly upon succulent
plants, as do the purely herbivorous species.
[Sidenote: Food problem of the Aryan races]
Man is by nature a tropical animal, and so long as his habitat was
confined to that section, he could live from the prodigality of
Nature, but when he began his early migration northward, his food was
the greatest problem he had to solve. He was often forced to choose
between eating the flesh of animals and death from starvation. It was
this fierce struggle for food, not the character of his food, which
exercised both the physical and the mental powers, and caused the Aryan
or northern races to think, and therefore to develop into people so much
superior to their tropical brothers.
[Sidenote: Forced to think and to work, man became civilized]
The defenders of flesh food often point to the fact that flesh-eating
people have achieved the highest civilization. Man's superior
achievement in northern countries can no more be credited to
flesh-eating than to the wearing of fur caps or leather boots. To meet
the exigencies of his environment, he was forced to think and to work,
and thinking and working developed the brain and laid the foundation for
his present stage of civilization.
Another reason for the early habit of flesh-eating is found in the
fact that in order to sustain the required amount of body-heat in cold
climates, a liberal consumption of fat was necessary. Vegetable fats
not being available, his only source of supply was from the body-fat of
animals.
[Sidenote: Use of meat unscientific]
Aside from fat, protein is the only nutritive element meat contains.
With the variety of vegetable and butter-fats, and vegetable proteids
available in this age, supplemented by our knowledge of chemistry as a
guide in their use, the consumption of flesh as an article of human food
is entirely unscientific and wholly without reason.
[Sidenote: Life MAY BE maintained by meat]
A diet composed exclusively of flesh contains fat and nitrogenous
compounds only. These two classes of foods can, of course, maintain
life, as was explained in our sixth lesson, as proteid is capable of
forming blood, sugar, and body-fat. The fact, however, that the proteid
or the fat of meat can be made to fill, in the physiological economy,
the place naturally supplied by the carbohydrate materials of vegetable
food, does not prove that such a diet is without its harmful effects.
The living body has many wonderful provisions whereby life is maintained
under unfavorable influences. Just as a blind person develops a sense of
touch which in a way acts as a substitute for sight, so the ability of
the body to convert either proteids or fats into sugar, may be utilized
in cases of emergency, but the using of this emergency or substitute
function of the body cannot develop and energize the human machine as
well or as perfectly as can a naturally balanced diet. The fact that
some people exist largely upon a meat diet does not prove that this is
without its handicapping and evil influences, any more than the use
of alcohol and tobacco proves that man is benefited by indulging in
intoxicants and sedative poisons.
[Sidenote: Flesh-eating produces appetite for stimulants]
That flesh-eating is largely responsible for the universal desire among
civilized people for some form of stimulant has ceased to be questioned
by those who have been placed in a position to make experiments--the
source from which all real knowledge is obtained. These conclusions were
first forced upon the writer by noticing the gradual decline of appetite
for coffee and tobacco in his own case, when he began to subsist upon
natural foods. With this hint no opportunity was lost, among the
thousands of patients he treated, to observe the effects and get at the
truth. If only one or two people had completely lost their appetite
for all forms of stimulation, after following a natural food regimen,
it might have revealed only an idiosyncrasy. When a dozen undergo the
same treatment, with the same results, it leaves but little doubt that
the theory may be true, but when many hundreds give the same testimony,
through a period of a dozen years' practise, it reveals a truth that
cannot be consistently doubted. Such experience proves beyond doubt
that flesh-eating supports and perpetuates the habit of taking distilled
and ardent liquors, tobacco, tea, and coffee, and the numerous drugs
which, altogether, have done the human race more harm; dethroned more
intelligence; sapped from the human economy more vitality; ruined more
homes; made more widows and orphans; changed more natural virtue into
vice, and caused more sorrow and tears, more failure and fears, than all
other agencies of destruction combined.
Since fats and proteids are the only nutrients supplied by flesh foods,
we may well ask, "Is meat the best source from which these elements may
be secured?"
[Sidenote: Flesh food contains unexcreted waste matter]
The proteid substance of meat includes all the edible portion of a
carcass except the fat. The proteid of meat is more easily and more
rapidly digested than the proteid of vegetables. Notwithstanding this
fact, there are serious objections to the use of meat as a source of
nitrogen. All flesh food contains the unexcreted waste matter of the
slaughtered animal. When the process of metabolism that is continually
going on during life is suddenly arrested by death, the effete and
decomposing cells, and the partly oxidized waste-products which are
still held in the muscle-tissues, are left in the flesh of the dead
animal, hence these poisons must be consumed by the flesh-eater in order
to secure the meat proteids and fats.
[Sidenote: Body-poisons generated by fear]
It is now a matter of common knowledge among scientists, and among
the more advanced school of pathologists, that the usual conditions
under which animals are slain change the chemical constituents of the
blood-serum, charging it with a form of poison that to the chemist is as
yet unknown, but the presence and the potency of which is attested by
its effect.
The method of slaughtering animals in the great abattoirs is especially
conducive to the generation of these poisons. The condemned herd is
driven to the place of slaughter and killed, one at a time, in plain
view of their fellows. These animals are very intelligent and possess
remarkable senses of danger. They are as conscious of approaching death
as the creature who takes their lives, hence the amount of poisons
generated in their bodies is measured by the time they are kept in
waiting. Most animals when killed labor under these conditions, and
that these mental states render their flesh entirely unfit for human
nutrition can no longer be questioned.
[Sidenote: Mother's milk poisoned by fear or anger]
We find fragments of evidence supporting this theory in the fact that
Nature's perfect food--the milk of a nursing animal, or of a nursing
mother--can be changed in an instant into a poison by sudden fright,
anger, or fear.
[Sidenote: Meat a source of autointoxication]
Thus we see that in eating meat, we are eating animal waste-material
similar to that thrown off through our own body-cells. The waste
material in meat being soluble, passes through the walls of our
digestive organs, and enters the circulation, where it is added to
similar poisons which are constantly being produced within our own
bodies. It is the universal law of animal cell-growth that the waste
matter of the cell acts as its own poison. When bacteria, growing in
a solution of sugar, have excreted alcohol until it forms a certain
percentage of the total contents, their activity ceases--they die from
poisons thrown off from their own bodies. This is the reason that
liquids containing a high percentage of alcohol must be distilled, and
cannot be brewed. It is obvious, therefore, that in the consumption
of flesh, we are adding to our bodies the poisons that are residual
in the body of other animals, and are, therefore, approaching the
conditions under which bacteria kill themselves by autointoxication or
self-poisoning.
Plants utilize the carbon dioxid excreted by the animal, and the
excrement of animals is in turn used to fertilize our fields. Although
one form of life may utilize what is excreted by another form of life,
the living thing that cannot get away from the excreted matter of its
own activity is poisoned thereby.
[Sidenote: Flesh food burdens the excretory organs]
The flesh of animals whose physiological processes are almost identical
with our own, containing as it does waste-products that have not yet
been excreted, must, when taken into the human body, add extra burdens
to our excretory organs which are usually burdened with all they can
do. Carnivorous animals are especially provided with an excretory
system capable of taking care of such matter, but it is unreasonable to
expect the excretory organs of man, which are not adapted to such a
purpose, to throw off, in addition to the regular body-poisons, similar
decomposing products of other animals.
[Sidenote: Flesh-eating will disappear as science advances]
It is true that flesh will support, and has supported what is commonly
regarded as a high form of anthropoid life (man), but not having the
natural standard from which to measure, we do not know how much better
the opposite course would have been, or just how much longer one would
live under a perfectly natural regimen. The effects of flesh-eating have
not been definitely known until recent years, but is now acknowledged
by the most advanced authorities to be one of the greatest errors of
civilized people, and will, within a few years, disappear from the
catalog of human habits, when the great masses of people are made
familiar with the chemistry of food, and how to secure vegetable instead
of animal proteids and fats.
MEAT
Meat, in the sense the word is here used, includes beef, mutton, pork,
and an occasional allowance of wild game. Chemically considered, meat
may be divided into two classes, namely (1) flesh or lean meat, and (2)
animal fats. The former will be first considered.
1 FLESH OR LEAN MEAT
[Sidenote: Composition of lean meat]
Lean meat is composed of the muscles of the animal. Approximately it is
70 per cent water, 20 per cent protein, and 10 per cent fat. The protein
is composed of connective tissue, which is a tough, fibrous substance
that forms tendons, and holds the muscle-cells in place. Chemically,
connective tissue is formed of albuminoids, which were discussed in
Lesson IV. These substances are somewhat difficult to digest, and are
not of very great importance in the human body, as they cannot take the
place of true proteid in tissue-formation.
The percentage of connective tissue in flesh depends upon the cut of
the meat. As every housewife knows, the cheapest cuts of meat contain a
larger amount of this material.
The gelatin of commerce is a manufactured product derived from the
connective tissue of animals.
Other forms of protein are globulin and myosin, which form the actual
muscle-substance. These elements form perhaps three-fourths of the
entire proteid of the animal, and are the most valuable substances of
flesh food. A very small portion of meat proteids is formed by the
free albumins of the blood, which are mechanically retained in the
muscle-cells, the purpose of which is the nourishment of the animal, and
therefore are not unwholesome as food.
[Sidenote: Meat extractives and their composition]
Another class of nitrogenous substances found in flesh foods is called
meat extractives. Though they exist only in quantities of from one to
two per cent of the weight of the flesh, they are the most interesting
from the standpoint of chemistry, because they are found only in flesh
foods, and are products only of cell life, hence not wholesome as food.
They are composed of urea, uric acid, creatin, etc., and are similar or
identical to the waste-products of human cell metabolism. The amount of
these substances contained in flesh depends upon the condition of the
animal at the time of slaughter, being much greater in animals slain
after the chase, or laboring under fear or abuse.
The chemical composition of the different cuts of meat does not vary
greatly, except in a greater or less per cent of fat, and no chemical
calculation can compute this accurately, as the fat in every cut of meat
varies widely.
[Sidenote: Prejudice against the hog]
Beef and mutton are comparatively the same in both nutritive value
and popularity, but the use of pork has been generally condemned the
world over. The reason for this is probably explained by prejudices of
tradition and religion, rather than by scientific or hygienic knowledge.
The prejudice against swine because of the filthy habits of the animal
is more a matter of sentiment than of science. It is sometimes the
custom among farmers to confine hogs in a pen, and to feed them upon
swill and garbage. This makes of the animal a filthy creature. However,
when left in the open fields or woods, they are as cleanly in their
habits as any of their brother animals. Corn and alfalfa-fed pork is
equally as wholesome as beef or mutton, when prepared in a similar
manner, and eaten in temperate quantities, while the hog fattened upon
acorns and herbs, in his native habitat (the woods), is much more
healthy, and his flesh really superior to most of his brother animals.
2 ANIMAL FATS
[Sidenote: Animal fats not a necessity]
The use of animal fats as food is a very ancient custom, especially
among the northern tribes. This custom was once justified owing to
the necessity for the consumption of a liberal amount of fats in
cold countries, but in this country where our marvelous system of
international transportation places at the door of every northern home
the delicious fats from the olive orchards of Italy, France, and Spain,
the refined oil from the cottonseed, and more than a dozen varieties of
nuts, including the humble peanut, there is but little necessity for the
use of animal fats except in the form of butter and cream.
[Sidenote: Chemical change in frying fats]
Perhaps the most injurious way in which animal fats are used is in
the process of frying, which is much practised in southern countries
in the preparation of other food. The chemical change which takes
place in fats, when treated in this manner, renders them exceedingly
indigestible, and almost wholly unfit for food.
That per cent of animal fats contained in the ordinary meat diet is
quite as wholesome as any other element of nutrition secured from animal
sources. However, with the splendid supply of vegetable fats civilized
people have to draw upon, the use of animal fats cannot be recommended
in any form except that of cream and butter, and when we consider the
expense of these by comparison with many pure vegetable fats, our sense
of ordinary economy would bid us discard them.
[Sidenote: Chemical difference between animal and vegetable fats]
The chief distinction between animal and vegetable fats is in the
proportion of olein compared with stearin and palmitin. The proportion
of the two latter fats is much greater in fats of domestic animals than
it is in the human body; this is especially so of tallow. For this
reason vegetable fats, which are of a more liquid nature, are more
desirable than those of animal origin, especially where we wish to add
fatty tissue to the body.
COLD STORAGE OF MEAT
A very small amount of the meat produced in this country at the present
time is consumed near its place of slaughter. Cold storage plants and
refrigerator cars have been constructed for the purpose of preserving
meats until they can reach their destination, and to hold them awaiting
market advances for the benefit of packers and tradesmen.
[Sidenote: Decomposition of cold storage meat]
Meat in cold storage is slowly undergoing a form of decomposition which
is evidenced by the fact that cold storage meat decays much more
rapidly upon its removal from storage than do the same cuts of fresh
meat.
The process of ripening meat in rooms of varying temperatures depends
upon this form of decomposition. The natural enzyms of the meat, and the
bacteria contained therein, digest a portion of the proteids, forming
nitrogenous decomposition products, similar to the above-mentioned meat
extractives. Ripened or storage meats contain a much larger per cent of
this group of compounds than does fresh meat.
[Sidenote: "Ripened meat" a step toward decay]
The high flavor and "peculiar rich taste" of ripened meats is produced
by these decomposition products, while the decay of the gelatinoid or
connective tissue is the primary reason for its tenderness. There are
certain species of bacteria that produce more poisonous waste-products
than others, and this occasionally causes the development of ptomains
in storage meat.
[Sidenote: A choice between two evils]
The use of flesh as an article of food is fraught with many serious
and scientific objections, but the use of cold storage or ripened
animal products is to be condemned from every standpoint of hygiene.
Nevertheless, if people insist upon using flesh foods, and economical
conditions make it profitable to produce them far from their place of
consumption, cold storage methods seem inevitable. The choice between
storage meats and home-killed is, in its last analysis, a matter of
selecting the lesser of two evils.
CONTAGIOUS DIS-EASES AND ANIMAL FOOD
[Sidenote: Rare beef unfit for food]
Much has been written as to how, from dis-eased animals, human beings
have contracted contagious dis-eases, especially tuberculosis. The
risk of such contagion has in all probability been much exaggerated.
Flesh foods are seldom taken in an uncooked form, and dis-ease germs
are usually destroyed by the sterilizing process involved in cooking.
The cooking process, however, must be very thorough in order to destroy
dis-ease germs; that is, the heat must be sufficient to coagulate the
proteids. The interior of a rare beefsteak, such as popularly demanded
by the flesh-eater, has not reached this temperature, hence this form of
meat should be condemned on this ground if for no other.
[Sidenote: Trichinosis]
Perhaps the worst form of dis-ease contamination from fresh flesh food
is that of trichinosis. Trichinae are worm-like creatures which have
the first stage of their growth in the flesh of swine, and then become
encased in a cyst or egg-like structure, which, when taken into the
human digestive organs are revived, and the trichinae then bore their
way through the walls of the digestive organs, completing their growth
in the human muscle-tissue. Trichinosis is one of the most fatal of
diseases, but fortunately is not common. Tapeworms owe their origin to a
similar source. There are several species of tapeworms; some have their
origin in pork, and some in beef.
FISH
Under this heading I will consider fish and other sea-creatures.
[Sidenote: Nutrients in fish]
[Sidenote: Fish as brain food]
The flesh of most fish is quite free from fat, and consists almost
entirely of water and proteids. It is less concentrated than the flesh
of warm-blooded animals, averaging about 18 to 20 per cent proteids, and
60 to 70 per cent water. The percentage of ash in fish is also somewhat
greater than in any other flesh food. The popular idea that fish is good
food for the brain originated in the fact that analysis of some fish
shows a considerable percentage of phosphorus, which substance is also
found in the brain. There is no reason to believe, however, that the
liberal use of fish would develop or produce an excess of brain-tissue.
Any well-balanced diet contains ample phosphorus to nourish the brain.
The true science of human nutrition lies in the knowledge of selecting,
combining, and proportioning food according to age, climate, and work.
When this is done, the tendency of the body is to eliminate dis-ease and
to assume normal action; this accomplished, every part of the anatomy
shares in the general improvement.
[Sidenote: Fish superior to flesh of mammals]
My theory advanced against the use of meat because of nitrogenous
decomposition products, holds true with fish, though in a somewhat
limited degree. The decomposition products of cold-blooded animals are
not identical with those of mammals, hence their consumption as food
does not add to the percentage of human waste-products so directly as do
other meats.
[Sidenote: Oysters and clams unfit for food]
Oysters and clams, which are generally eaten uncooked, are recommended
by many authorities as valuable sources of proteid. The serious
objection to their use, and especially uncooked, is the fact that they
are grown in the sea-water around harbor entrances which are flooded
with sewage, and hence they are likely to be contaminated with typhoid,
or similar germs. The actual food value in shell-fish is quite small.
They contain only about ten per cent of proteids, and are scarcely worth
considering as a source of nutrition.
POULTRY AS AN ARTICLE OF FOOD
The objections that I have made against the use of the flesh of fish
and mammals as an article of food may also be assessed against the use
of domestic and wild fowls. There are a few special points, however, in
favor of poultry as food that are worth special consideration.
The production of chickens and other domestic poultry is one of the
most prolific industries in America, and is of great importance to the
general public because it is capable of being carried on in communities
too thickly settled for the economic production of beef and other meats.
[Sidenote: Poultry superior to the flesh of mammals]
Another point to be observed in the use of poultry as food is that,
because of the ease with which every farmer and villager can keep a
flock of chickens, it is possible for him to have fresh meat produced
under the most sanitary and hygienic conditions, while if he uses meat
as food, he will be compelled to depend upon the various meat products
of unknown age and origin, secured from the general market.
Another reason why the use of poultry, from a hygienic standpoint, is
less objectionable than the use of pork and beef is that the quantity
consumed is usually much smaller than the amount eaten of these
heavy-blooded meats.
For example: When five pounds of beefsteak is purchased in the market,
the amount consumed would be almost the full weight of the purchase. If
the money were invested in a five-pound chicken, a goodly portion of
this weight would be lost in preparing the fowl for the table, while
a still further loss would occur in the bones and in the inedible
portions, so that the actual amount of flesh consumed would not be more
than perhaps two pounds.
According to the old idea of economy and diet, this would be a serious
argument against the use of poultry products, but as has been clearly
proved in this course of lessons, the most serious criticism that can be
urged against the modern bill of fare is quantity, and especially the
use of meat in large quantities, so common among the American people.
[Sidenote: Custom vs. hygiene]
The chief reason for which meat is kept upon the bill of fare of most
civilized people is that of conformity to custom, surely not to that of
hygiene. That form of meat, therefore, which is pleasing to the taste,
and which has a tendency to reduce the quantity of flesh consumed, is a
step in the right direction of true food reform.
EFFECTS OF FEEDING POULTRY
[Sidenote: Fattening poultry]
The methods of fattening poultry by shutting them in small coops or
compartments, and feeding them upon soft mushy foods, is condemned by
some writers on the ground that it is unnatural and harmful to the
health of the fowls, and therefore the meat cannot be wholesome. In
truth, this process, if not carried too far, will produce a quality of
meat less harmful than that of the barnyard and ill-fed poultry. One of
the greatest objections to the use of animal food, as already explained,
is the presence of the unexcreted waste-products of animal metabolism.
The flesh of fowls, fed and fattened in coops, contains the smallest
possible quantity of waste or decomposition products, because of the
limited amount of motion or exercise they are permitted to undergo. For
this reason, when poultry is to be eaten, the whiter the meat the less
objectionable it is as an article of food.
[Sidenote: Marketing poultry undrawn]
The marketing of poultry in an undrawn condition (without the removal
of the internal organs), has been much condemned by the public, and the
legislatures of some states have passed laws against this practise.
This, however, is to some extent a misapplication of good intentions.
When poultry is to be killed for the market by those who thoroughly
understand the business, the fowls are left without food for a period of
twenty-four hours. Since the digestive processes of these small animals
are very rapid, this results in emptying the intestines of most of the
fecal matter, which removes the principal objection to the practise.
On the other hand, if the fowls are drawn at the time of killing, and
several days elapse before their consumption, bacteria gain access to
the interior of the carcass and cause very rapid decomposition.
[Sidenote: "Hanging" poultry]
It is the practise in some oriental and European countries to "hang"
poultry for a few days before they are eaten. This process, as in the
case of ripened meats, is simply one of partial decay. The enzymotic
action taking place in the meat is arrested only by the process of cold
storage. Decomposition proceeds slowly until it reaches that point when
it is pronounced high-flavored and "ripened." This is very largely
practised in this country at the present time. It is a custom that is
instinctively condemned by everyone from the standpoint of both hygiene
and aestheticism. The people should demand and force Congress to pass a
law labeling all cold storage meats with the date of slaughter, and all
canned meats with the date of packing.
[Sidenote: Slaughter of game as sport, a step backward]
What is true of domestic poultry is also true of all wild game. The
amount of actual food contributed to the world by the slaughter of game
is exceedingly small. A similar quantity of domestic food could be
produced at one-tenth the cost of time and labor, without slaughtering
the wild creatures of our forests. The popularity of hunting as a sport,
and the idea that the flesh of all wild animals is a rare and dainty
article of diet, is merely an illustration of anthropoid inheritance. It
is a step backward toward savagery instead of forward toward a higher
civilization.
EGGS
Eggs and milk occupy a unique place in the catalog of foods. The purpose
for which they were produced in nature throws much light upon their
value as food.
[Sidenote: Every form of life exists for itself alone]
As will be learned from the lesson, "Evolution of Man," no living
creature exists for the sole benefit of other creatures, but because
once created, the inherent struggle of all living matter to survive
and to reproduce itself has evolved wonderful and various adaptations.
Every organic substance is primarily produced in nature for a specific
purpose in the life of its species. The lumber in our houses owes its
existence to the plant's struggle for sunlight, which made it necessary
for the tree to possess a strong storm-withstanding stem to hold aloft
its leaves above the shade of other foliage.
The leaves and the stems of grass are primarily an essential part of the
life of the plant, and not food for animals. The greater part of the
human food of plant origin represents in nature the nutrient material
supplied by the parent plant for the early life of the seedling. All
grains, nuts, fruits and roots, and tubers are merely modified forms of
food material adapted to the rapid nourishment of the young plant.
The starch and the oil of seeds, the sugar of fruit, and the lesser
quantities of nitrogen contained in all seeds, are in a more available
form for cell-nourishment than would be the original mature portions of
plant life.
Milk and eggs in the animal world occupy a position identical to that of
seeds and fruit in the plant world; that is, they are created for the
first nourishment of the offspring.
In the process of evolution, a fundamental distinction between birds and
mammals is in the manner in which the young are nourished. The egg of
the bird supplies sufficient nourishment to develop the young bird to a
point where it can exist upon the ordinary food of the adult bird.
The hen's egg must contain all food material necessary to form all
portions of the body of the chick, and to supply it for a time with heat
and energy.
[Sidenote: Composition of eggs]
An average egg weighs two ounces; of this weight about 10 per cent is
shell, 30 per cent yolk, and the remainder white. The white of the
egg is composed of albumin and water. The yolk consists of globulin,
egg-fat, and lecithin; this latter substance contains a considerable
proportion of phosphorus, and is one of the essential contingents of
brain and nerves. The egg-shell contains 13 per cent protein, 10 per
cent fat, and one per cent ash.
[Sidenote: Milk and eggs not a balanced adult diet]
The younger the animal, the more rapid is the growth of the animal
body compared with the amount of energy expended. For this reason the
percentage of nitrogen in milk and in eggs is much too great to form a
balanced adult diet, and should be supplemented by articles containing
larger proportions of heat-producing materials, preferably carbohydrates.
[Sidenote: Eggs for emaciation and convalescents]
The proteid material of eggs is in a form especially adapted to the
construction of new cells. For this reason it is one of the best known
foods for use in cases of emaciation, where new tissue is to be added
rapidly to the body. An egg contains about fourteen decigrams of
nitrogen. Ten eggs, therefore, would supply an ample amount of nitrogen
for the daily needs of the average body, were no nitrogen taken from
other sources. In feeding patients who are convalescing from fevers or
other wasting dis-eases, it is sometimes necessary to prescribe a diet
of from ten to twelve eggs daily for a limited time.
The consumption of five eggs a day, when we rely wholly upon this
article for animal proteids, is quite sufficient for one performing
ordinary labor, when supplemented by one succulent and one tuber
vegetable.
MILK
[Sidenote: Milk the best animal food]
Milk and the various products made therefrom constitute one of the most
important groups of food in the modern bill of fare. Milk and eggs are
interdicted by some vegetarians, but aside from the sentimental feeling
against the taking of any food of animal origin, there are no scientific
reasons for such exclusion. Dairy products are free from many of the
objections assessed against the use of flesh, and they supply a number
of readily soluble, digestible, and assimilable nutrients that, in many
respects (curative and remedial feeding), excel anything that can be
secured from the vegetable kingdom.
[Sidenote: Results of special feeding]
The composition of cow's milk varies widely. Dairy cows, by long
domestication, breeding and feeding, have been brought to a high state
of specialization. Some breeds have been so trained, fed, and bred as
to produce large quantities of milk. Some Holsteins have been known to
produce one hundred pounds of milk per day each, which of course is many
times the quantity required for the nourishment of their young. Some
Jersey stock have been so bred, raised, and fed as to produce large
quantities of butter; in some cases the butter-fat of especially fed
Jerseys has been known to run as high as 8 or 10 per cent, whereas the
normal fat content of milk is not more than 3.5 or 4 per cent.
The average composition of mixed milk from many cows runs about as
follows: Water, 87 per cent; lactose or milk-sugar, 4.5 per cent;
butter-fat, 3.5 per cent; ash, .7 per cent; proteids, 3.3 per cent, of
which about 2.5 per cent are casein, and .8 per cent albumin.
[Sidenote: Value of milk depends upon its nitrogenous content]
The commercial value of milk is measured almost entirely by its content
of butter-fat. This is because the public knows practically nothing
about the food value, or the chemistry of milk, therefore its value is
estimated upon that which can be seen, and upon that which tastes best.
The chief value of milk as a food lies in the nitrogenous element it
contains. Fat can be secured from many other sources.
The nutritive elements of milk from various animals vary according to
the natural requirements of the young of various species.
Cow's milk contains too large a proportion of casein, and not enough
milk-sugar to meet the natural requirements of the human infant. This
subject, however, will be discussed at length in Lesson XVI on "Infant
Feeding," Vol. V, p. 1154.
[Sidenote: Coagulation of casein in milk]
The casein in cow's milk is coagulated by the hydrochloric acid of the
stomach, which forms into lumps or curds, rather difficult to digest.
This can be overcome or counteracted in several ways. First, if milk is
allowed to sour or clabber, the casein is coagulated by nature, which is
really the first process of digestion. In this form it neither burdens
the digestion nor causes the supersecretion of hydrochloric acid, which
is likely to occur when sweet milk is too liberally used. Second, the
sipping and thorough insalivation of milk, by taking it into the mouth
with something that requires thorough mastication, insures better
digestion and assimilation, and less liability to produce intestinal gas.
Milk will harmonize chemically with all non-acid fruits, cereals and
nuts. Milk is in chemical harmony with meat and eggs, but all of these
articles being highly nitrogenous, when taken at the same meal, the
portions should be limited to the minimum.
Milk should not be combined with acid fruits, especially those of
a highly acidulous character, such as lemons, limes, grapefruit,
pineapples, etc. (See Lesson VIII, Vol. II, p. 314.) Neither should
it be taken at the same meals with succulent plants, such as lettuce,
watercress, romaine, parsley, etc.
[Sidenote: Milk for sour or acid stomach]
When the stomach has long been over-burdened with food, and made the
receptacle in which acid fermentation has taken place until the mucous
membrane has become irritated or probably ulcerated, there is no food
so acceptable as milk. For the common disorder of hyperchlorhydria,
which is a term used to describe a condition of chronic sour stomach
or supersecretion of hydrochloric acid, milk is one of Nature's best
counteractive food nutrients. (See "Superacidity," Vol. II, p. 418.)
In cases of severe constipation or alimentary congestion, milk should be
given as follows:
[Sidenote: Milk diet for constipation]
Omit breakfast. Begin about 9:30 taking an ordinary glassful of fresh,
cool milk every twenty or thirty minutes, until about one and one-half
quarts have been consumed. After two or three hours, repeat the same
process until about two quarts more have been taken. With each quart
of milk, from three to four heaping dessert-spoonfuls of clean, wheat
bran should be taken, in thin cream or rich milk. At noon and at evening
a few tablespoonfuls of coarse cereal (wheat or rye flakes), might be
eaten. They should be masticated thoroughly, and eaten with nuts and
a limited quantity of cream. Under this regimen I have known the most
severe cases of constipation to yield readily, and the patient to make
a gain in weight of half a pound daily for a period of from twenty
to thirty days. If the appetite should rebel against taking milk in
this quantity, the amount should be reduced, and a cupful of soaked
evaporated apricots taken at night just before retiring, and in the
morning, just after rising.
When milk is taken for the purpose of counteracting a congested
condition of the bowels, or an irritated condition of the mucous
membrane of the stomach, it should be combined with the fewest possible
things--one coarse cereal only will give the best results. A large
quantity of milk, three and one-half to four quarts taken daily, as
above directed, will act as a laxative, while a small quantity will have
a tendency toward constipation.
THE ADULTERATION OF MILK
The old method of adulterating milk with water has very largely gone
out of practise, owing to the surveillance of city authorities, and the
passing of laws that fix legal standards, which require milk to contain
a certain percentage of fats and total solids.
[Sidenote: Evil of milk preservatives]
The chief form of criminal tampering with milk has been the use of
preservatives to prevent souring. Formaldehyde has been used very
extensively for this purpose. Formaldehyde is a poison, destructive to
all cell life, and has probably been the cause of more actual deaths
than any other form of food adulteration.
MILK PASTEURIZATION
Pasteurization, which takes its name from Pasteur, the French
bacteriologist, is merely a process of heating milk to about 170 degrees
Fahrenheit for the purpose of destroying possible dis-ease germs, and
the bacteria that produce fermentation. In this process the milk is
not allowed to come to a boil for the reason that boiled milk is rather
"dead" or distasteful, and would readily be detected by the public. It
is quite evident that any method of Pasteurization, which would kill
bacteria, would also cause coagulation of the protoplasm and the albumin
of the milk, and render it much less nutritious, and much more difficult
to digest.
[Sidenote: Virtue of naturally soured milk]
If milk producers and dairymen understood the superior food and remedial
value of naturally soured milk, and would exert some effort to educate
the public in its use, they would soon establish a new and profitable
industry, and would give the dairy business of the whole country a new
commercial impetus. The souring of milk can be prevented by cleanliness,
which renders Pasteurizing unnecessary. At the time of the Paris
Exposition, a dairy farm in Illinois sent pure unpasteurized milk to
Paris, which arrived in an unsoured condition. This was achieved by
absolute cleanliness, with the cows, dairy utensils, etc.
CHEESE
Cheese consists of the coagulated casein of milk, together with the
fat globules that may be mechanically retained. Cheese is made by
coagulating the milk with rennet, which has been extracted from the
stomach of a calf, the sugar of the milk being passed off in the whey,
and lost.
Schmier Käse or cottage cheese is formed by allowing the milk to sour,
and to coagulate by gradual warming. This cheese is usually made from
skimmed milk, hence contains practically no fat.
[Sidenote: The several processes of making cheese]
The cheese of commerce is ripened in various ways. The process of
ripening is due to the action of enzyms present in the milk, or to those
formed by bacterial growth. Ripened cheese is considered to be more
easily digested than the unripened product. The best that can be said
of this process is that the ripening of cheese is perhaps the least
objectionable of all processes of decomposition taking place in food
proteids. The only benefit that can be claimed is one of flavor, and, in
matters of flavor, the appetite for Limburger, and similar cheeses, is
at least a cultivated taste that furnishes evidence neither of merit nor
of nutrition.
In the manufacture of cheese, the milk, sugar, and a part of the albumin
and fat are wasted, and as there are no advantages in taking the milk
in this changed form, there exists no scientific reason for the use of
cheese when fresh milk can be obtained.
BUTTER
Butter constitutes one of the most wholesome and palatable of all animal
fats, and is probably one of the most extensively used articles of food
of animal origin.
When the pure butter-fat has been separated from the casein of milk
it can be kept sweet and wholesome for a length of time sufficient to
transport it, and to pass it through the various links in the chain of
commerce, so that it can reach the family table a long distance from
its source of production. This, in addition to man's instinctive relish
for dairy products, makes butter the most popular fat in the diet of
civilized man.
[Sidenote: Fresh butter made in the home]
In prescribing butter-fat, however, it is advisable to nominate fresh,
unsalted, or what is commonly termed "sweet" butter. It is also
advisable for the practitioner to suggest that this can be made daily,
merely by whipping either sweet or soured cream with an ordinary rotary
egg beater until the fat globules have separated from the whey.
Pure butter contains about 3,600 heat-calories to the pound, and
therefore constitutes one of the most important and readily convertible
of all winter foods.
If no other fat is used, about two ounces of butter each twenty-four
hours is sufficient to give the ordinary body, under a temperature
ranging from forty to sixty degrees above zero, the required amount of
heat.
OLEOMARGARIN
Oleomargarin is a general term that includes all manufactured
preparations of fats which imitate dairy butter.
Oleomargarin is manufactured by combining beef-fat with cottonseed-oil
until a product is formed which has a melting point similar to that
of butter. Lard is also used in some oleomargarin products. This
combination of fats is then churned with either cream or milk and dairy
butter is frequently added so as to give to the artificial product
the pleasant flavor or odor of dairy butter. There is much popular
prejudice against the use of oleomargarin, but when made under hygienic
conditions, and by cleanly methods, it is practically as digestible, and
quite as wholesome as the dairy product.
+--------------------------------------------------------------+
| Transcriber's notes: |
| |
| The side notes appear before the paragraph they are situated |
| in the text file. |
| |
| P.64. 'NaCL' changed to 'NaCl'. |
| P.236. 'vegetarianisn' changed to 'vegetarianism'. |
| P.238. 'escargoes' changed to 'escargots'. |
| Both dis-ease and disease are found in this book, leaving as |
| it is. |
| Fixed various punctuation. |
+--------------------------------------------------------------+
*** End of this LibraryBlog Digital Book "Encyclopedia of Diet - A Treatise on the Food Question, Vol. 1 of 5" ***
Copyright 2023 LibraryBlog. All rights reserved.