teins and nuclein. Nucleic acid is rich in phosphorus and
upon decomposition yields some of the purin bases (xanthin,
adenin, guanin), a carbohydrate and phosphoric acid.^
(6) Phosphoproteins. — Compounds in which the phos-
phorus is in organic union with the protein molecule other-
wise than a nucleic acid or lecithin. Examples: caseinogin
(milk), ovovitellin (egg yolk).
'"The Basis of Nutrition/' by Graham Lusk.
'Food Products," by Henry Sherman.
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22 DIETETICS FOR NTJESES
(c) Hemoglobin. — Much of the greater part of the iron
existing in the body occurs as a constituent of the hemo-
globin of the red blood cells. When the intake of iron is
not sufficient to cover the output, there must be a conse-
quent diminution in the hemoglobin of the blood with a
corresponding development of anemia.
The importance of knowing these characteristic proteins,
is apparent. Not only will such knowledge lead to a more
intelligent use of protein foods in the normal dietary, but
it will prove of the greatest assistance in the adjusting of
the foodstuffs in diet for individuals suffering from certain
abnormal conditions.
In abnormal conditions this knowledge of the various
proteins — their composition, source, and behavior in the
body assumes a position of the greatest importance; since
it represents the means for safeguarding a patient from the
results caused by the wrong kind of food. In certain types
of nephritis, for example, it is perfectly safe to give milk'
where the ingestion of meat and eggs might cause serious,
if not fatal, results. In treating gout, when it is deemed
advisable to limit the purin foods in order to control in a
measure the retention of uric acid in the body, the reali-
zation that certain of the nucleoproteins, upon being
broken down in the body, yield the purins, which in
turn give rise to the production of uric acid, will permit
the nurse to adjust the diet so as to eliminate such foods
entirely (see Gout). The importance of keeping the
hemoglobin content of the blood normal has already been
mentioned.
The Effect of Heat upon Proteins. — The fact that cer-
tain proteins are most susceptible to heat has already been
stated, but the application of this knowledge in the prepara-
tion of protein foods is important. In milk, for example,
whole raw milk forms a large hard curd; whereas boiled
milk curdles in a much finer and softer form. Pasteurized
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FOOD 23
milk shows smaller curds than raw whole milk, but larger
than the boiled whole milk.®
An egg cooked by the application of a long continued
high temperature (212T.) has a tough white; whereas an
egg cooked until hard at a temperature under the boiling
point shows a tenderness in the white which renders it
distinctly more palatable. Soft cooked eggs leave the
stomach in less time than is required for hard cooked ones;
poached (cooked in water under the boiling point), shirred
eggs (cooked in hot dish), and soft cooked eggs are among
the most readily digestible forms of eggs. Raw eggs are
slightly less stimulating to acid secretion in the stomach and
require a longer time to leave the stomach than boiled eggs.
Thus it is seen that in many cases the difference in prepara-
tion of the protein foods may make a difference in the way
in which the digestive tract handles them. Necessarily, this
point is emphasized more in abnormal than in normal condi-
tions; for example, albuminized orange juice gives rise to
a distinct gastric secretion, and leaves the stomach rapidly
— a great advantage in certain abnormal conditions, and
especially in those requiring liquid diet of high nutriment
value.
The knowledge of the coagulation of proteins by heat
points out the advantage of using cold water over hot in
the preliminary cleansing of utensils in which protein foods
have been prepared. Certain members of this group are
soluble in pure water, and will readily dissolve; whereas,
if the water is heated, their coagulation would prevent
this taking place so readily.
Functions of Protein in the Body. — The proteins serve
two distinct uses in the body; first, that of building and
repairing tissues and furnishing, in conjunction with other
'Abstracts made from thirteen papers from the Laboratory of Physio-
logical Chemistry, Jefferson Medical College, Philadelphia; published in
the "American Journal of Physiology and Science," by Minna C. Denton,
U. S. Department of Agriculture.
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24 DIETETICS FOR NURSES
substances, material for growth; second, that of producing
energy for the internal and external work of the body. For
this latter function a large percentage of the proteins in-
gested is used; consequently, since the carbohydrates and
fats axe primarily the energy furnishing material most
readily used by the organism, it is clearly demonstrated that
the average individual takes more protein into the body
than is necessary for its maintenance. Except during the
period when an allowance for growth must be made, it
is probable that a much smaller daily consumption of pro-
tein could be made without disadvantage to the organism,
leaving the bulk of the work, in so far as the running of the
engine is concerned, to the other organic foodstuffs.
WATER
Man can exist for days, even weeks, without food, but
without water life soon becomes extinct. This substance is
composed of hydrogen and oxygen in the proportion of two
to one; that is, to each atom of oxygen there will be found
two atoms of hydrogen. This is always the case no matter
where it is found. When foods are put through a drying
process the water is taken out and the rest of the chemical
composition of the food remains unchanged.
This foodstuff, unlike those belonging to the organic
group, is not changed during the process of digestion, nor
does the application of heat or cold affect it, save from a
physical standpoint. Water boils at a temperature of
100° C. (212° F.), and freezes at a temperature of 0° C.
(32° R).
Function of Water. — The uses of water in the body
are many, and the advantage arising from a sufficient
amount of this foodstuff in the dietary cannot be overesti-
mated. It is no longer considered an error in diet to drink
a moderate amount of water with the meals, so long as it
is not used as a substitute for mastication, and as a means
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FOOD 25
of washing the food into the stomach. In the diet, both
as a beverage and as a part of most of the food materials
ingested, water serves to moisten the tissues; to furnish the
fluid medium for all of the secretions and excretions of the
body; to carry food materials in solution to all parts of the
organism; to stimulate secretory cells producing the diges-
tive juices, thereby aiding in the processes of digestion,
absorption and excretion; to promote circulation; to furnish
material for free diuresis, thus preventing to a great extent
the retention of injurious substances by the body, which
might otherwise take place.
Factors Determining the Amount of Water Needed.
— In normal conditions it is probable that the kind and
amount of exercise taken has more to do with the amount
of water needed by the body than any other factor, since
the vigorously worked body excretes more water by way of
the skin than the quiescent one. With a normal amount of
exercise, it is advisable to drink from six to eight glasses
of water each day, increasing the amount to a certain extent
when exercise causes a great loss through perspiration. It
is always advisable, however, to keep in mind that an exces-
sive amount of fluid taken into the body throws a corre-
^onding amount of work on the organs (the stomach, kid-
neys and heart). In certain abnormal conditions, the
body's water supply is depleted. This is particularly true
in the case of hemorrhage, vomiting, and diarrhea. Under
other conditions (certain types of nephritis), the body be-
comes overburdened through the excess of water retained,
owing to the difficulty which the kidneys show in eliminat-
ing it. This retention of water by the tissues gives rise to
the condition known as edema.
MINERAL SALTS
Ash. — The eight remaining chemical elements, i.e.,
calcium, magnesium, sulphur, iron, sodium, potassiunx,
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26 DIETETICS FOR NTJESES
phosphorus, chlorine, constituting the mineral salts or ash,
are likewise classed as food on account of the work which
they perform in the body. Some of these elements enter
the body as essential constituents of the organic compounds,
and are metabolized in the body as such, becoming inor-
ganic only upon oxidation of the organic materials of which >
they form a part.
Importance of the Mineral Salts. — The way in which
the mineral elements exist in the body and take part in
its functions, has been graphically outlined by Sherman as
follows.
"(1) As bone constituents, giving rigidity and relative
permanence to the skeletal tissues. (2) As essential ele-
ments of the organic compounds which are the chief solids
of the soft tissues (muscles, blood cells, etc.). (3) As solu-
ble salts (electrolytes) held in solution in the fluids of the
body; giving to those fluids their characteristic influence
upon the elasticity and irritability of muscle and nerve;
supplying material for the acidity and alkalinity of the di-
gestive juices and other secretions; and yet maintaining
the neutrality, or slight alkalescence, of the internal fluids
as well as their osmotic pressure and solvent power." ^
The above outline, showing the various ways in which,
the mineral constituents enter and take part in the various
functions, as well as in the structure of the body, make it
evident that the same close attention and study which was
given to the other foodstuffs must be accorded to these sub-
stances. When the student realizes that the presence of
certain salts dissolved in the blood assists in the regula-
tion of the vital processes of the body such as the digestion,
circulation and respiration; that they are responsible for
the contraction and relaxation of the muscles; that they as-
sist in controlling the nerves; that they are, in a way, in-
• ''Chemistry of Food and Nutrition" (revised), p. 333, by Henry ^ler-
man.
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FOOD 27
strumental in releasing the energy locked up in food — the
value of these elements becomes very evident, and their
importance in the dietary inestimable. Some of the mineral
salts are more widely distributed in food than others, and
the danger arising from their deficiency in the diet is not
so great as is the case with others; hence attention is called
to those found by investigators to be most often lacking or
deficient in the average diet; ie., calcium, phosphorus, and
iron. A brief summary of the special parts played by these
elements will be outlined here.
Calcium. — Physiology teaches that about eighty-five
per cent, of the mineral matter of the bone, or at least three-
quarters of the ash of the entire body, consists of calcium
phosphates. It has long been known that this mineral salt
is necessary for the coagulation of the blood, and science
has demonstrated that "the alternate contractions and re-
laxations which constitute the normal beating of the heart
are dependent, at least in part, upon the presence of a suffi-
cient, but not excessive concentration of calcium salts in
the fluid which bathes the heart muscles." ^®
Phosphorus. — According to Sherman, phosphorus
compounds are as widely distributed in the body, and as
strictly essential to every living cell as are proteins. Science
has also proved that they are important constituents in the
skeleton, in milk, in glandular tissue, in sexual elements, and
in the nervous system; that these compounds take part
in the functions of cell multiplication, in the activation and
control of enzyme actions, in the maintenance of neutrality
in the body; that they exert an influence on the osmotic
pressure and surface tension of the body, and upon the pro-
cesses of absorption and secretion. Like calcium, phos-
phorus is absolutely essential to the growth and develop-
ment of the body, and, as in the case of the mineral, its
presence in the dietary must be accorded strict attention, in
"•"Chemistry of Food and Nutrition" (revised edition), by Sherman.
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28 DIETETICS FOR NURSES
order to avoid the results accruing from its deficiency.
Casein, or caseinogen of milk and egg yolk (ovovitellin), are
the substances richest in this mineral salt The fact that
the phosphorus existing in grains (cereals) may be removed
largely in the process of milling, makes it advisable to
consider the use of the breads made from the whole grains.
Iron. — The presence of iron as an essential constitu-
ent of hemoglobin has already been discussed. That which
is not in the hemoglobin is chiefly found in the chromatin
substances of the cells.
The body does not keep a reserve store of iron on hand
as is the case with calcium and phosphorus in the bone
tissues, but must depend upon the daily intake in food to
supply its needs. The iron content of food materials is
not large, but a careful regulation of the iron bearing foods
(see Table on page 5) will make it easy to cover the de-
mands of the body with a material which has been found
to do its work most efficiently. Medicinal iron has received
much attention in the determination of the essential needs
of the body. "Whether medicinal iron actually serves as
material for the construction of hemoglobin is not positively
known, but we have what appears to be a good evidence
that food iron is assimilated and used for growth and for
regeneration of the hemoglobin to much better advantage
than are inorganic or synthetic forms, and that when me-
dicinal iron increases the production of hemoglobin, its
effect is more beneficial in proportion as food iron is more
abundant — a strong indication that the medicinal iron acts
by stimulation rather than as material for the construction
of hemoglobin" (Sherman).
The newborn infant has a store of iron already on hand,
derived from the mother through the placenta before birth.
After the birth, and through the nursing period, the child
receives a certain amount of iron from the mother's milk.
This supply is not altogether reliable, however, since any
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POOD 29
disturbance of the digestion will tend to interfere with its
absorption, and consequently deprive the organism of what
would otherwise be used for the building up of the blood
supply. Thus it is clearly indicated that the infant's safest
source of iron is from the mother during the pre-natal
period. This supply must necessarily come from her diet
during this time, and is made possible by r^ulating day
by day the iron bearing foods in her dietary. After the
original store of iron is reduced to that of the adult (after
the child has tripled in birth-weight, generally at 12 or 13
months), and during the remainder of the growth period,
it is very necessary to regulate the iron-bearing food in
the diet, in order to insure the child of an adequate amount
to cover the demands made by the increasing blood supply.
VITAMINES
Up to a few years ago it was believed a complete diet
should contain an adequate amount of protein of a proper
t3T)e, a suflBcient amount of calcium phosphorus and iron,
and enough carbohydrates and fats to furnish the body with
sufficient fuel to cover its energy expenditures. This belief
was proved to be incorrect a number of years ago by Dr.
Hopkins of England. In making certain feeding experi-
ments with rats. Dr. Hopkins showed that some sub-
stance or substances present in milk, other than those al-
ready mentioned, was essential for the growth of the animal ;
that animals deprived of this material grew for a time, but
gradually ceased to do so. Later on, Osborne, Mendel,
McCollum and Davis discovered a like substance in butter
fat; and still later Dr. McCollum found the same growth
stimulating material, or one very like it, existing in the
leaves of plants. These scientists found, upon investiga-
tion, that there were probably two substances in milk — one
soluble in the fat, the other in the protein-free and fat-free
whey — both of which were essential for normal growth. In
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30 DIETETICS FOR NURSES
1911 Dr. Funk discovered in rice polishings a substance
which he believed to be a cure and preventive of Beri-
beri; to this substance, which is now believed to be iden-
tical with the second substance found in milk, he gave the
name "vitamine." Dr. Funk's name "Vitamine" is now ac-
cepted to cover a number of substances essential to growth,
and for the prevention and cure of certain diseases. To
the first two has been added a third member of the vitamine
family, which has proved to be a cure and preventive of
scurvy. These substances are called — on account of the
substances in which they are soluble — "Fat soluble A,''
"Water soluble B," and "Water soluble C." The table on
page 496 shows the sources from which these factors may
be obtained. The four plus system is used by Dr. Eddy to
describe the abundance with which they occur.^^
Function of "Fat Soluble A." — All investigators agree
that the "A" vitamine is an essential factor in the growth of
young tissue, and the repair of nature tissues. McCoUum
claims that this vitamine is likewise a factor in the pre-
vention of the eye disease known as xerophthalmia, and
other scientists also hold this opinion. Eddy states that a
diet lacking in the "A'* vitamine will, in the majority of
cases, result in stunted growth and the development of the
eye disease, and that the appearance of the latter may be
taken as a sure indication of the absence or deficiency of
this vitamine.
The following diagram shows the effect of adding fat
soluble "A" to the diet which was adequate in other re-
spects. This chart represents the growth curve of young
rats."
Mellanbly of England believes the "A" vitamine to be
a factor in the prevention of rickets. Scientists of America
have recently investigated this disease, and Dr. Hess (New
""The Vitamine Manual," p. 64, by Walter Eddy
"Courtesy of Dr. E. V. McCollum.
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FOOD
31
York) has found cod liver oil to be a remedy for it. Cod
liver oil is known to be rich in "Fat soluble A," but whether
the cure of rickets is due to the presence of this vitamine in
the oil, or to a possible fourth vitamine, is still undeter-
mined.
Effect or Heat on the "A" Vitamine. — Heat, as ap-
plied in the ordinary methods of cooking, is not believed to
exert a great deal of destruction upon the "A" type of
vitamine; but hydrogenation, the proc-
ess used in the hardening of certain
fats in the manufacture of lard sub-
stitutes, is said to destroy it completely.
"Water Soluble B." — The second
vitamine discovered in milk and be-
lieved to be identical with the Funk
vitamine is more widely distributed
than the "A" vitamine. For this reason
it is not so likely to be deficient in the
diet as is found to be the case with the
"A." A glance at the table shows that ^. ^ ^.
° Time "» Months
the best sources outside of yeast are the p^^^ showing the
seeds of plants and the milk and eggs effect upon growth of
of animals. In beans and peas the "B" a" t°^a diet adequate
vitamine is distributed throughout the coui^oTD^E'^V
entire seed, but in the cereal grains McCollum.
it is found chiefly in the embryo. As a result, bread made
from fine white flour or meal is much more apt to be defi-
cient in vitamine of the '*B'' type than that which is made
from the whole grain; the same is true of rice and other
cereals. Spinach, potatoes, carrots and turnips show an
appreciable amount of the vitamine, but beets are known
to be extremely poor in it. Nuts too are considered a
valuable source.
Function of the "B" Vitamine. — Like the "A'' vita-
mine, water soluble "B'' is believed to be essential to growth.
Digitized by
Google
32 DIETETICS FOR NURSES •
Funk established its value as a preventive and cure of Beri-
beri, the disease common in the Orient among people living
largely upon a diet of polished rice and fish. Besides being
a growth-stimulating substance and an antineuritic, the
"B" vitamine is highly valued for its stimulating effect upon
the appetite. To this property is probably due at least
part of the credit for which certain substances work for
the promotion of growth in animals. This can be utilized
to good advantage for children showing a disposition to re-
fuse food, by supplementing formulas made from milk,^*
with the expressed juice of vegetables and fruits known to
be rich in the "B" vitamine.
EflFect of Heat on the "B'' Vitamine. — This vitamine
also shows a resistance to heat; that is, as applied in the
methods generally used in cooking, pasteurization tempera-
tures do not materially affect the vitamine property of the
formula as far as the "A" and "B" factors are concerned. '
The EfiFect of Alkali (Soda) upon the "B" Vitamine.
— It has been an ordinary practice to add soda to the
water in which certain vegetables are cooked, for the osten-
sible purpose of softening the vegetables and hastening their
cooking. This practice has been condemned by many scien-
tists who are making experiments along these lines, on
account of its destructive power upon the "B" vitamine.
Chick and Hume in England claim that when the amount
of food given contains originally just sufficient vitamines
to cover the growth factor the use of soda in the cooking
water does serious harm to these vitamines. This is a
point well worth remembering. It is often difficult to per-
suade certain individuals to eat vegetables in appreciable
quantities; if the vitamines were reduced througji the
method of preparing the food, these individuals would not
obtain a sufficient quantity of the vitamines.
"Milk from cows whose diet has been deficient in vitamines shows a
like deficiency in vitamine content — the same is true of mother's milk.
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FOOD 33
"Water Soluble C." — The third member of the vita-
mine family is known for its antiscorbutic property; that
is, it is the best known cure and preventive of scurvy.
It likewise exerts a certain amount of influence upon the
growth of the animal and must be present in the diet, in
order that the health and well-being of the individual may
be safeguarded. The "C" vitamine, like the "B" vitamine,
is soluble in water, and is present to an appreciable extent
in the fresh juices of the fruits and vegetables. Some are
richer in this respect than others (orange and tomato juice),
while the cereals, grains, seed of plants, sugars, oils, and
meats are singularly deficient. Milk (whole) does not con-
tain a great amount of the "C" vitamine, and this amount
is still further reduced under certain methods of preparation.
Milk powders, made either from the whole or the skimmed
milk, are found to contain only very small amounts of this
essential substance. Condensed milk and cream are sup-
posed to be free of "C/' and the same is true of eggs.
££Fect of Heat on "C" Vitamine. — All authorities
agree that the "C" vitamine is much more sensitive to heat
than the other two; and for this reason much of the value
obtained from this vitamine in uncooked material may be
lost when the food containing it is subjected to long con-
tinued heat. Hess claims that the temperature used for
pasteurizing milk for some time, is more destructive to this
vitamine than boiling water temperature continued for a
few minutes only.^^ There is need for care in formulating
the diet for children to see that they are given fresh fruit
every day; or when that is not possible, to see that they are
at least given tomato juice. This substance is rich in the
antiscorbutic vitamine, and according to experiments made
by Sherman, LeMer and Campbell, loses fifty per cent, of
its antiscorbutic power when boiled one hour. Dr. Delf at
the Lister Institute experimented with raw and cooked
""The Vitamine Manual," p. 64, by Walter H. Eddy.
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34 DIETETICS FOR NURSES
cabbage, and found that when this material was cooked for
one hour at temperatures ranging from 80"^ to 90^ C the
loss in antiscorbutic power amounted to 90 % in the
cooked leaves over the raw material. Dr. Delf also con-
cluded from her experiments that it was advisable to add
neither acid nor alkali in the cooking of vegetables if these