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[Illustration: _Susanna Cocroft._]
What to Eat and When
By
Susanna Cocroft
Author of
“Let’s Be Healthy,” “The Woman Worth While”
“Growth in Silence,” etc.
_Fourth Edition_
_With Additions and Revisions to Date_
_Illustrated_
G. P. Putnam’s Sons
New York and London
The Knickerbocker Press
1916
COPYRIGHT, 1916
BY
SUSANNA COCROFT
The Knickerbocker Press, New York
PREFACE
THE subject of dietetics has only of late years begun to come into
its own. For centuries it was thought that the body was a thing to be
neglected and despised; that it was a clog to the soul. The teachings
of dogma and the life of the hermit and the ascetic glorified the
mortification of the body and the elevation of the soul.
The study of the functions of life and the manner in which those
functions are upheld and vivified—the development of the sciences of
Biology and Physiology—have placed the relations of the body and its
inhabitant the soul on a more consistent and rational basis. It is
coming to be recognized that the mind cannot function to its highest
efficiency in a body below par; that in order to work harmoniously
and to accomplish the most for humanity, the sound mind must dwell
in a sound body, with all of its functions active, its organs in
vigorous condition, kept so by a thorough assimilation and a forceful
circulation. These are to be secured by means of daily exercise,
abundance of fresh air, and healthful, happy, constructive thoughts.
It has been well said that the distinguishing feature between man
and other animals is the fact that he is a cooking animal. Until he
discovered fire man’s subsistence was little more than that of the
brute. Out of his discovery of the varied uses of this element came
modern civilization. Much of this advance was made possible through the
added strength of mind that was given man by a more varied diet. His
limited raw diet gave little scope to his inventive faculties. From the
discovery of the possibilities in cooked food his mind was stimulated
to research in other directions. With the lessened need for vigorous
mastication, however, the degeneration of man’s teeth began and we
are slowly learning now that exercise for the teeth and gums is as
necessary for their health as it is for the rest of the body.
Dietetics is, in itself, both an Art and a Science. Food can be
prepared so tastefully and its appearance made so pleasing as to become
a fit subject for a painter. But the selection of food that shall give
the body all the elements it needs in its work of growth and repair,
with the greatest economy of effort, of purse, of time, and of energy,
needs the trained judgment, the knowledge of comparative values and of
chemical combinations possessed by a scientist. This is especially true
from the fact that so many bodily ills result from a faulty digestion,
due either to the food itself or to the condition of the organs which
must handle the food.
The subject is so vast and its ramifications so many that all
the resources of chemistry own themselves baffled at some of its
intricacies. However, an intelligent working knowledge of the
processes undergone by food in its progress through the body, and its
transformation into vital force, can be attained by anyone.
This book is the outcome of years of experience in correcting bodily
ills caused by wrong hygienic habits. It has been written out of a
sincere desire to awaken the every-day individual to the important
relation that food bears to his well-being.
Much has been written on this subject by medical men for the medical
profession, in language too technical for the layman. It is believed
that in this book the layman will find a fund of information hitherto
not available to him, in language stripped of technicalities, plain and
easily understood. I have tried to make it logical and interesting.
When the American people become convinced that a thing is needed they
generally “go after” it, and sooner or later the desired thing is
attained. When they arouse themselves to see that the food they eat is
pure, well prepared, and taken into digestive systems vigorous by means
of proper exercise and fresh air, a new and far more virile race will
be the outcome.
Acknowledgment is here made of the valuable assistance of Winfield S.
Hall, Ph.D., M.D., Professor of Physiology in the Northwestern Medical
School, Lecturer, and Author of _Nutrition and Dietetics_; of Alida
Frances Pattee, late Instructor in Dietetics, Bellevue Training School
for Nurses, Bellevue Hospital, New York City, Author of _Practical
Dietetics_.
The tables of Food Values and the classification of foods are kindly
furnished by Dr. Hall and used by the courtesy of his publishers,
while a few of the recipes are generously furnished by Miss Pattee.
Recognition is also made of the good work of Miss Helen Hammel, former
dietitian in Wesley Hospital, Chicago, in the preparation of some of
the recipes.
THE AUTHOR.
INTRODUCTION
The problem of proper nutrition for the body is as vital as any study
affecting the morals, health, and consequent power of a nation, since
on the quality and quantity of food they assimilate, depend the
sustenance, health, and strength of its citizens.
The food eaten by a nation largely determines the character of that
nation.
No subject is so vital to the individual, to the family, the community,
the nation, as health. No education is so vital as a knowledge of
foods, sanitation, hygiene.
Health is the basis of happiness and the attainment of happiness is
man’s chief pursuit. The very foundation of national life is the
education of its citizens in its preservation. The nation seeks
prosperity and happiness—yet true prosperity is based on these
fundamentals.
Money can be expended for no object which will yield the nation, or the
individual, greater returns than in the acquisition of a knowledge of
how to keep well. Health specialists, in the future, will direct their
work more to the prevention than to the cure of diseases.
The strongest powers are those which most fully guard the health of
their citizens. The endurance of an army lies in the strength of the
individual soldier.
The basic work for “preparedness” is in building the bulwarks of
physical strength and endurance.
The study of life is of most vital interest. The enjoyment and
maintenance of life is inbred. It is intuitive. The infant’s first
instinct is the preservation of life; almost immediately he seeks for
nourishment.
His body is an ever awakening wonder to him. He begins his education by
testing his lungs, by studying his hands, his legs, and his flesh.
The human race spends more time in providing nourishment for the body
than in any other line of activity. Yet we are wasteful; we have not
studied to make the food yield its greatest nourishment and the body
its greatest efficiency.
Unless the system is thoroughly nourished we miss much of the physical
satisfaction of life; we miss the joys of mental development, the
inspiration of soul, the sense of growth, of freedom, of expansion, and
the self-satisfaction of accomplishing. The satisfaction resulting from
greatest usefulness and the enjoyment of the results of usefulness, the
greatest blessings and the largest measure of life come only to those
whose nutriment is proper in quantity and quality, taken properly as to
time, and is thoroughly assimilated, because both body and brain are
thereby enabled to develop most fully.
The enjoyment of vibrant life, of bodily efficiency, is far beyond the
fancied joys of the intemperate or the ascetic.
That one may thoroughly enjoy life in the freedom which comes from
perfect activity of bodily functions, it is necessary that proper
_habits_ be formed, then the energy of thought is not constantly
engaged in deciding what is best. Habit calls for no conscious
expenditure of energy.
Nutrition is a broad subject. It means not only that the foods be
supplied which contain elements required to rebuild body substance and
to create heat and energy, but it embraces, also, the ability of the
body to appropriate the foods to its needs.
The study of nutrition in its full sense, therefore, must embrace not
only foods, but anatomy and physiology (particularly of the digestive
system). A knowledge of chemistry is also necessary that we may know
the changes foods undergo in being converted into tissue, heat, and
energy.[1] This science is known as Dietetics.
Scientific research along the lines of electricity, psychology,
metaphysics, medicine, and art has been tenaciously pursued for
centuries; yet scientific study of the natural means of keeping the
body in health, that the individual may be in physical, mental, and
moral condition to enjoy and to profit by researches made in other
lines, has been neglected.
The entire framework of the body—bone, muscle, blood, brain, and
nerve—as well as the heat and the mental and physical energy necessary
for every motion is supplied from food and drink, and from the oxygen
breathed into the lungs.
We are learning that derangements of the body are largely caused by
injudicious eating, yet, vital as it is, the subject of foods, except
in recent years, has not had a place in the courses of study in our
public schools.
We have given much attention to the “pound of cure,” but insufficient
attention to the “ounce of prevention.” Man does not enjoy life to its
full, nor do his physical or mental efforts yield him his best returns
unless his system is thoroughly nourished.
Formerly, the physician gave general directions, or none at all, as to
the diet. His directions, when given, were often indefinite because the
subject was not definitely understood, due to the fact that the course
of instruction in medical colleges contained practically nothing on the
subject of foods. This study is not in the curriculum of all of our
medical colleges to-day.
Our public-school curriculum contains no more important study than that
of health and of the simple, hygienic laws which enable us to retain
it. The science of foods in their relation to health, sanitation,
and general hygiene should be among the foremost requirements of our
public-school courses of study. Mothers’ clubs will find no more
interesting or profitable study than Dietetics.
It is coming to be widely recognized that a far larger number of
diseases arise from the food habit than from the liquor habit. Many who
look with contempt or pity on the victims of alcohol, are themselves
diseased of body through the unintelligent use of food.
Habitual overeating not only produces diseases of the digestive organs,
from overwork and excessive secretory activity, but also of the
excretory and glandular system, as the kidneys and the liver, and may
give rise to functional disturbances of the heart.
Food, if taken in greater quantity than the digestive juices can
handle, either passes out of the system without being absorbed or it
ferments or decomposes, giving rise to constipation, diarrhea, or other
intestinal disturbances.
If the stomach and intestines are active and can handle the excess of
food, its absorption beyond what the system requires overloads the
blood and causes obesity or diseases of the skin and kidneys. It thus
brings about abnormal deposits as in gout, or the calculi found in the
kidney or the gall-bladder. Biliousness and congestion of the liver may
follow, with constant headache, coated tongue, foul breath, and languor
of body and of mind.
Many habitually eat too much and take too little fluid, though, due to
a greater spread of knowledge, overeating is becoming less common.
On the other hand, an insufficient or illy balanced diet will bring
in its train disorders of the system scarcely less harmful. A large
number, particularly of young girls, take insufficient food, eat
irregularly, and are undernourished.
When one does not eat sufficient food or the proper kind and variety,
the tissues of the digestive organs are undernourished and do their
work imperfectly.
The undernourished are usually those who work at high tension, those
who worry, or those who do not get bodily exercise proportionate to the
mental.
Mental workers are liable to become preoccupied and forget to take
food. Growing girls who are over-interested in studies, anxious
concerning examinations, etc., neglect their meals. Parents are often
to blame in these cases by unduly encouraging the intellectual effort.
Members of some religious sects practice undereating as a form
of asceticism; many others from poverty are unable to procure a
sufficient amount of food.
Too many, if not the majority of those concerned with the purchase
and preparation of food, understand but little of food values and
the importance of their proper combination. No matter how simple the
menu, it should embrace the elements the system needs for its complete
sustenance.
The problem of nutrition must be solved largely through chemistry.
The health and efficiency of the individual and of the nation depend
on careful study of the foods placed on the market, their chemical
components, and their possible adulteration.
Happily the United States Government, realizing that its power as
a nation depends on the strength and health of its citizens, has
established experimental and analytical food departments. As a result
of the findings of the government chemists, there was enacted in 1906,
the Food and Drugs Act, which has raised the standard of food purity,
by prescribing the conditions under which foods may be manufactured and
sold. The law compels the maker of artificially colored or preserved
food products to correctly label his goods. The national law instigated
the passage of various state laws, which have further helped to insure
a supply of pure food products; yet we need other laws which shall have
greater efficiency and wider scope.
The strength of Germany as a nation is due very largely to the
government supervision of foods manufactured and imported.
There is no more important branch of the United States Government than
that which protects the health of its citizens.
The custom among some nations of retaining a physician to _maintain_
the health of the family rather than to _regain_ it, to _avoid_ disease
rather than to _cure_ it, has its distinct advantages.
We should not be satisfied with anything less than perfect health and
we are beginning to realize that this perfect health is a possibility
for almost every individual.
In the maintenance of health, as well as in the cure of disease, diet
is often more important than drugs.
To-day, scientific knowledge of hygiene and of food values is within
the reach of all, and every mother and teacher may learn how to guard
the health of those in her charge.
It is necessary to know the comparative values of foods as nutrient
agents, in order to maintain our bodies in health and strength, and
with economy of digestive effort, as well as efficiency.
There is no study, therefore, more important than that of bodily
nutrition, which comprises not only the right proportion of food and
drink, but also the manner in which they must be prepared in order
to yield the best returns under varying conditions—age, employment,
health, and sickness.
The body is certainly a marvelous machine! It is self-building,
self-repairing, and, to a degree, self-regulating.
It appropriates to its use foodstuffs for growth and for repair.
It eliminates its waste.
It supplies the energy for rebuilding, and eliminating this waste.
It directs its own emotions.
It supplies the energy for these emotions.
It discriminates in the selection of food and casts out refuse and
foodstuffs not needed.
It forms brain cells and creates mental force with which to control the
organism.
It keeps in repair the nerves, which are the telegraph wires connecting
the brain with all parts of the body.
It converts the potential energy in the food into heat with which to
keep itself warm.
Withal it is not left entirely free to do its work automatically. It
has within it a higher intelligence, a spiritual force, which may
definitely hamper its workings by getting a wrong control of the
telegraph wires, thus interfering with the digestion, the heart action,
the lungs, and all metabolic changes. The right exercise of this higher
intelligence, in turn, depends on the condition of the body, because
when the mechanism of the body is out of repair it hampers mental and
spiritual control.
About one-third of the food eaten goes to maintain the life of the
body in its incessant work of repairing and rebuilding, the remaining
two-thirds being held in reserve for other activities.
One of the most remarkable and the least understood of any of the
assimilative and absorptive functions, is the ability shown by one part
of the body to appropriate from the foods the elements necessary for
its own rebuilding, while the same elements pass through other organs
untouched. The body has the power, also, not only to make use of the
foods, but to use up the blood tissue itself. Just how this is done is
also a mystery.
There is surely a great lesson in industry here, and one of the most
profound studies in economics, physics, and chemistry.
Habitual worriers use up force and become thin more quickly than those
whose work is muscular. Those who spend their lives fretting over
existing conditions, or worrying over things which never happen, use up
much brain force and create disagreeable conditions within, resulting
in digestive ills. These again react on the body and continue the
process of impoverishment of the tissues.
Certain it is that improper foods affect the disposition, retard the
spiritual growth, and change the current of one’s life and of the
lives about one. Therefore the intelligent care of the body—the medium
through which the soul communicates with material surroundings—is a
Christian duty.
“The priest with liver trouble and the parishioner with indigestion, do
not evidence that skilled Christian living so essential to the higher
life.”
Man has become so engrossed and hedged about with the complex demands
of social, civic, and, domestic life, all of which call for undue
energy and annoyance and lead him into careless or extravagant habits
of eating and living, that he forgets to apply the intelligence which
he puts into his business to the care of the machine which does the
work. Yet the simple laws of nature in the care of the body are plainer
and easier to follow than the complex habits which he forms.
The “simple life” embraces the habits of eating as well as the habits
of doing and of thinking.
_The whole problem of perfect health and efficient activity is in
keeping the supply of assimilated food equal to the demand, in keeping
a forceful circulation that the nourishment may freely reach all
tissues and the waste be eliminated, and in full breathing habits
that sufficient oxygen be supplied to put the waste in condition for
elimination._
FOOTNOTES:
[1] It is impossible in this book to go into the anatomy and physiology
of digestion exhaustively. The reader is respectfully referred to Miss
Cocroft’s book on _Let’s Be Healthy_. This traces the food through the
digestive canal, indicating the juices which act on it, putting it into
the state in which it can be absorbed by the body and appropriated to
its various uses.
CONTENTS
CHAPTER I
PURPOSES OF FOOD
PAGE
Production of heat and energy; derivation of food
elements; composition of the body; building
and repair of cells; necessity of exercise; food
elements as used in body building 1-7
CHAPTER II
CLASSIFICATION OF FOOD ELEMENTS
Definition of food stuffs, of foods; basis of classifications
of foods; tabulations of classes of foods and
foodstuffs; proteins or tissue builders; carbonaceous
foodstuffs; carbohydrates; fat; water; mineral
salts 8-37
CHAPTER III
CLASSIFICATION OF FOODS
Carbonaceous: roots and tubers, green vegetables,
fruits; nitrogenous: flesh, fish, eggs; carbo-nitrogenous:
cereals and cereal preparations, legumes,
nuts, milk and milk products; table of food values 38-102
CHAPTER IV
HEAT AND ENERGY
BEVERAGES AND APPETIZERS
Tea; coffee; cocoa and chocolate; lemonade and other
fruit drinks; effervescing waters; condiments and
spices; vinegars; sauces; food adulteration; preservation
of foods; heat and energy 103-129
CHAPTER V
REPAIR AND ELIMINATION OF WASTE
(METABOLISM)
Chemical changes in foods in body; work of assimilation;
food reserve; digestion, its processes and
ferments; absorption of food; economy in food;
selection of foods for need of body; mouth and
nasal passages 130-150
CHAPTER VI
ORGANS AND CONDITIONS AFFECTING DIGESTION
The liver, the muscles, the nerves, the kidneys, the skin,
the intestines, the blood, summary of work of
organs and tissues; season and climate; habit and
regularity of eating; frequency of meals; exercise
and breathing; ventilation; fatigue; sleep; influence
of thought; the circulation; gum chewing;
tobacco and alcohol 151-184
CHAPTER VII
COOKING
Importance of proper cooking; purposes of cooking;
meats; cereals and cereal products; vegetables;
fruits 185-199
CHAPTER VIII
FOOD REQUIREMENTS OF THE SYSTEM
Elements determining quantity of food necessary;
selection of dietary food required by workers at
various occupations; average requirement; energy
derived from various foods; mixed diet versus
vegetarian diet 200-215
CHAPTER IX
DIETS
Constructing balanced meals; in sedentary occupations;
the girl or boy from thirteen to twenty-one;
the athlete; the laboring man; condition of “age”;
model diets; tables of use in making up a balanced
diet 216-241
CHAPTER X
DIET IN ABNORMAL CONDITIONS
Importance of proper diet in conditions of disease;
anemia: indigestion or dyspepsia; gastritis,
dilatation of the stomach; intestinal disorders;
constipation; derangements of the liver; gall
stones; neuralgia; kidney derangements; excess
of uric acid; asthma; tuberculosis; neurasthenia;
skin diseases; when traveling; in convalescence;
leanness; obesity 242-304
CHAPTER XI
RECIPES FOR FOODS FOR INVALIDS AND SEMI-INVALIDS
Waters; fruit juices; liquid foods; farinaceous beverages;
meat juices; semi-solid foods; gruels; souffles 305-319
CHAPTER XII
INFANT FEEDING
Problem of correct feeding; breast feeding; wet nursing;
contra-indications to nursing; anatomy and
physiology of the infant; intestinal disturbance;
times of feeding; water; normal development in
the breast-fed; weaning; artificial feeding; bacteriology;
composition of human milk; top-milk; top-milk
mixture; certified milk; milk modifications;
sterilizing and pasteurizing; comparative analysis
of milks and infant foods; gruels; vomiting; colic;
the stools in infancy; constipation; diarrhea;
anemia rickets; scurvy; feeding the second year 320-356
APPENDIX
MEASURES AND WEIGHTS 357-359
INDEX 361-366
ILLUSTRATIONS
PAGE
SUSANNA COCROFT _Frontispiece_
DIAGRAMMATIC REPRESENTATION OF VILLUS 146
What to Eat and When
CHAPTER I
PURPOSES OF FOOD
The purposes of food are:
To supply the material out of which the body may rebuild the tissues.
To produce heat, and to liberate muscular and mental energy.
Every particle of body substance is constantly changing. The new
material for cells and tissues, the substance to supply the energy
needed in the metabolic work of tearing down and rebuilding, the energy
used in the digestive process of converting the food into condition
to be assimilated, and the energy used in muscular, brain, and nerve
movement must all be supplied by food.
Every effort of the brain in the process of thinking, every motion, and
every muscular movement requires energy which the food must supply.
The body is composed of a vast number of cells varying according to
the tissue or organ in which they are found. The characteristic of all
living matter is that it constantly reproduces itself. Cells perform
their appointed work, wear out, and must be replaced by new ones or
derangements follow.
The new cells constantly being formed, increase in size and in so doing
push the worn-out, dying, and dead cells out of the way. The process of
building and eliminating continues within the body and on its surface
every instant of life.
An idea of the number of dead cells constantly being thrown off from
every part of the body may be gained by noticing the amount of dead
skin cast off. The fine scales of “scarf” or “dead” skin, which we
easily rub off in a friction bath, are composed of these dead cells
which have been crowded out by the hosts of vital cells constantly
forming beneath. The process is the same in every tissue and organ. The
dead or worn-out matter within the body is burned by oxygen and put in
condition to be carried by the blood to the organs of elimination, the
kidneys, intestines, lungs, and skin.
Much waste is eliminated in liquid form through the sweat glands. It
is said that stokers throw off four pounds of water and waste a day
through the skin.
In the growing child the process of building and of eliminating is
active and rapid. In the youth it is less rapid, in the adult still
less, but unless the process is kept active, stagnation and death ensue.
_Daily exercise is necessary to keep up the body activities; yet very
few take the trouble to secure daily a complete, thorough circulation
of blood, especially through the vital organs and the deeper tissues.
Perfect circulation is the key-note of health._
Activity of any kind necessitates the expenditure of energy. The
process is a chemical one and in all chemical processes heat
is necessary to cause the decomposition of elements and their
recomposition into different substances.
Heat in its turn has two functions. It enables the chemical changes to
be carried on which fit the food for the use of the various tissues,
and it burns to an ash the worn-out products of the body’s activity,
fitting them for elimination.
It keeps the tissues flexible and the secretions fluid; coagulation
takes place when the secretions become cold.
As previously stated, food in the body, then, is needed for two
purposes:
(1) to build and maintain the cell until its work is done;
(2) to furnish the heat necessary to decompose the food into its
elements, and to produce the energy by which all the body processes are
carried on.
[Sidenote: Food Elements]
That the food may be appropriated by the body it must be not only
proper in kind and quantity, but the body must also be in condition to
digest, absorb, and assimilate it and to eliminate the waste, otherwise
the body needs are not met.
It is the nourishment which _the body assimilates and appropriates to
its needs_ which counts in food economy, _not necessarily the amount
consumed_.
Therefore if the food is to economically serve its purpose, the body
must be in a condition to digest and assimilate it—_this condition
depends largely on perfect circulation, correct position of organs, and
correct breathing habits_.
Of the fifteen to twenty substances contained in foods and comprised in
the body, the principal ones are oxygen, hydrogen, carbon, nitrogen,
chlorin, sodium, potassium, magnesium, iron, calcium, phosphorus, and
sulphur. The differences in the forms of matter lie in the proportions
in which these elements are combined.
Those containing the largest proportion of nitrogen are called
_Nitrogenous_ foods or _Protein_—such as meat, eggs, and some
vegetables.
Those containing the largest proportion of carbon are known as
_Carbonaceous_—such as cereals, sugar, and fat.
The four food elements, indispensable to life, either of plant or
animal, are oxygen, hydrogen, carbon and nitrogen.
Carbon combined with oxygen forms carbon dioxid.
Oxygen, nitrogen, and carbon dioxid largely form the air.
Oxygen and hydrogen form water.
Calcium, iron, magnesium, sodium, and potassium are used in the
formation of the various tissues and secretions of the body.
The substances contained in living organisms are the same as those in
inorganic matter, only in different complexities as appropriated to the
needs of each organism.
The difference between living and non-living matter is in the relative
proportion and arrangement of the same elements.
Before it is fit to supply the needs of the body, the raw material must
undergo a chemical change.
It has been demonstrated by scientific investigation that no
unorganized elements, such as pure nitrogen, pure iron or magnesium,
are assimilated by the system and converted into its various
structures.
While the body needs carbon, it cannot use coal; it needs nitrogen,
yet it cannot appropriate it to rebuilding bone and muscle, until, by
chemical action with other elements, it has been converted into complex
substances called proteins.
The muscles, ligaments, and labor-performing structures contain the
largest amount of nitrogen.
The fat contains the largest amount of carbon.
The brain, the nerves, and the bones contain the largest proportion of
phosphorus compounds.
Yet, while the brain contains phosphorus, and the tissues nitrogen,
the brain cannot be built up by eating elementary phosphorus, nor the
muscles by pure nitrogen, but compounds rich in phosphorus or nitrogen
may be utilized.
Plants use the simple compounds of the earth, air, and soil, and,
within their own cells, build them up into such complex substances as
starch, sugar, protein, fat, and salts, putting them in condition for
man and other animals to appropriate to their use.
All plant life is compounded from the elements in the soil, air, and
water, by the action of the sun’s rays. The rays of heat and light
store something of their power in latent heat and energy in these plant
compounds.
The end of plant life is the completion of its compounds—when it has
matured them, the plant dies.
All organic matter is thus formed by the action of the sun’s rays on
inorganic matter.
The gluten of wheat is formed from the chemical union of nitrogen in
the air and nitrogen in the soil with other substances.
The starch of wheat and other grains is from carbon which the plant
has taken from the soil and combined with other substances.
All meats are largely derived from plants which have appropriated
the elements from the soil, water, and air. The chemical processes
of the animal convert the energy latent in the plant foods into the
more concentrated form of meat. The animal thus performs a part of
the chemical work for man—the digestive organs of one animal convert
the food contained in certain plants, into a substance more easily
assimilated by another animal.
Man would need to eat a large amount of nitrogen-containing plants in
order to get as much protein as is contained in one egg or in a piece
of lean meat the size of an egg. It is because the nitrogen is in
such condensed form in meat and eggs that one is likely to take more
than the system can handle, if he eats too freely of these two foods,
particularly of meat. We will discuss this question more fully under
“Proteins.”
Most domestic animals take their food elements from air and water, as
well as from the compounds which the plants have formed, while wild
animals and some domestic ones, such as hogs and chickens, make use of
meat as well.
The greater part of muscle, nerve, and gland is composed of _protein_.
When the muscles are exercised constantly they use up their protein and
must have it resupplied, or the muscle substance will waste. When the
muscles are exercised freely, as in the laborer, or the athlete, they
need more building material.
The skeleton is composed largely of deposited _salts_, as _calcium_.
If, therefore, the growing child be not supplied with a sufficient
amount of this substance, the bones will be weak and liable to
deformity and the teeth will be slow in coming or will be small and
malformed. Children need foods rich in lime.
The elements which supply heat and keep up muscular activity are
_starches, fats, and sugars_.
It must be apparent to every thoughtful person, that, since the nerves,
muscles, and glands are composed largely of protein and the skeleton
largely of calcium salts, in order to furnish the body with the
elements necessary for growth and repair, all of these elements, as
also the energy-producing substances, must be provided.
_Each individual, therefore, should learn how much he requires to
replace his daily waste, both for rebuilding tissue and for supplying
heat and energy._
The day laborer, though he may do more muscular work than an athlete in
training, expends scarcely any nervous energy. Therefore he needs less
protein in his diet than one does who expends both nervous and muscular
activity, as does the athlete.