substances were to give their maximum value of vitamines.
From the foregoing description of these vitamine fac-
tors, it is readily seen why so many dietaries are deficient
in these essential substances. The limited sources from
which to obtain the "A" vitamine ; the sensitiveness of the
"B" vitamine to the action of alkalies; the sensitiveness
of the "C" vitamine to heat, alkali and acid, moreover the
limitation of its presence chiefly to the fresh fruits and
plant juices, — all point to the need of special care in the
selection of the food materials and of the manner in which
these materials are prepared for consumption.
SUMMARY
In the descriptions just given of the various foodstuffs,
especially in regard to their function in the body, it is read-
ily seen that no one foodstuff is used to the exclusion of
another. It is further seen that in the upkeep of the body,
which includes not only the building and repairing of its tis-
sues, but the running of the engine and maintaining of its
normal temperature, the organism uses each and all of
the organic food substances for the production of heat.
Furthermore, while the tissues are chiefly built from protein
material, and physiology teaches that protein can be built
only from other protein, these tissues contain a certain
amount of carbohydrate, fat, mineral salts, and water; this
furnishes distinct evidence that the building of the cells
and tissues of the body cannot be accomplished by means
of protein alone, but by the judicious balancing of all the
foodstuffs in the dietary.
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FOOD 35
Science has gone even further than this, as has just
been demonstrated, and has proven that without the sub-
stances known as vitamines the normal growth and devel-
opment in the young would be arrested, and that the main-
tenance of the adult body would be impaired. It has also
proven that certain diseases owe their development to de-
ficiencies in the vitamine supply to the body.
PROBLEMS
(a) Outline briefly what is believed to be the essentials of
an adequate dietary.
(b) List the fuel foods and show their most economical
source.
(c) List the best sources of the complete proteins.
(d) Show how the incomplete protein foods may be made
adequate for growth.
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CHAPTER II
THE FUEL VALUE OF FOOD
Science has proved that the human body is composed
of certain chemical elements and that food materials are
combinations of like elements; it has likewise proved that
the body will utilize her own structure for fuel to carry
on the work of her various functions unless material is
supplied for this purpose from an outside source, jiamely,
food, which in chemical composition so closely resembles
that of the human body.
Amount and Type of Food, — The next point of in-
vestigation would logically be the amount and kind of
food necessary to best accomplish this purpose. To be able
to do this it was necessary to have some standard unit by
which to measure the amount of heat each food was capa-
ble of producing when burned outside the body, after
which it was more or less simple to calculate the heat pro-
duction of each of the food combinations within the organ-
ism. An apparatus known as the "Bomb Calorimeter" ^
was devised by Berthelot, and adapted for the examination
of food materials by Atwater and Blakesley. The food ma-
terial to be tested was placed within the bomb, which was
charged with a known amount of pure oxygen. The bomb
was then sealed and immersed in a weighed amount of pure
water, into which a very delicate thermometer was inserted.
The food within the bomb was ignited by means of an
electric fuse, and the heat given off by the burning of the
material was communicated to the surrounding water and
* For full description and methods used, see "Journal of The American
Chemical Society," July, 1903.
36
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THE FUEL VALUE OF FOOD 37
was registered upon the thermometer. It was evident that
some definite name had to be devised by which these heat
units might be known. Hence the name "calorie," which
represents the amount of heat required to raise the temperor
ture of 1 kilogram of pure water 1 degree centigrade, or
about 4 pounds of water 2 degrees Fahrenheit.
Transformation of Foods into Available Fuel. — A
comparison has been made between the human body and
steam engine, but this comparison is not adequate, since
the food does not produce heat within the body originally,
but energy of which heat is a by-product. Each food com-
bination has a certain amount of dormant energy within its
structure and this energy does not become active nor can
it be utilized by the body until the food, of which it is a
part, is changed within the organism to substances more
nearly like its own. This liberated active energy is then
used as a motive power to carry on the internal and ex-
ternal work of the body, and the heat, which is invariably
the consequence of any active energy (motion), leaves the
body as such. It will be seen, then, that the human body
acts not as a steam engine, but rather as a transforming
machine by means of which the dormant energy of the food
is transformed into an active agent of which heat is a nat-
ural result.
In the calorimeter it was found that the carbohydrates
and fats burned to the same end products, namely, carbon
dioxide and water, while the proteins, upon oxidation, pro-
duced carbon dioxide, water, and nitrogen gas. In the body
it was found that the carbohydrates and the fats acted in
exactly the same manner as in the calorimeter, producing
the same end products. But this was not the case with the
proteins; the oxidation process of this chemical combina-
tion was found to be not nearly so complete within the body
as in the calorimeter, and instead of the free nitrogen as
produced in the apparatus there were urea and other ni-
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38 DIETETICS FOR NURSES
trogenous substances eliminated which, while combustible,
represented a less complete oxidation of the proteins.
The following table represents the amount of heat pro-
duced as the result of a complete oxidation of the food-
stuffs in the calorimeter.
TABLE •
Carbohydrates 4.1 cal. per gram
Fats 9.45 cal. per gram
Protein (nitrogen X 6.25) . . . 5.95 cal. per gram
The loss of potential energy due to the incomplete oxida-
tion of the proteins in the body is approximately 1.2 calories
to each gram of protein in food; consequently in calculat-
ing the fuel value of protein foods, due allowance must be
made for these losses. Allowance must also be made for
the incomplete digestion, or losses occurring in the diges-
tion, of the foodstuffs. These losses, as well as the approxi-
mate amount of each constituent absorbed, are represented
in the following table.®
Lost
A hsorhed
Carbohydrates
Fats
2 per cent
5 per cent
8 per cent
98 per cent
95 per cent
92 per cent
Proteins
The physiological fuel factors of food, or the amount of
heat produced as the result of combustion of 1 gram of
organic food material after the above mentioned losses have
been accounted for, may be obtained as follows.^
Carbohydrates . . . . 4.1 X 98% = 4 cal. per gram
Fats 9.45 X 95% = 9 cal. per gram
Proteins 4.35 X 92% = 4 cal. per gram
■"Chemistry of Food and Nutrition" (revised edition), by Sherman.
■"Chemistry of Food and Nutrition," by Sherman.
* "Chemistry of Food and Nutrition" (revised), by Shermaa
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THE FUEL VALUE OF FOOD 39
EFFECT OF HEAT AND COU> UPON THE FOODSTUFFS
In primeval days, when man led a more natural life, his
very existence depended upon his ability to wrest from the
earth his 4 — 9, — 4; these, then, constitute what are
known as the "physiological fuel factors" of carbohydrates,
fats, and proteins respectively.
Determination of Fuel Value of Food. — In determin-
ing the amount of heat produced by a given amount of
food, it is first essential to reduce the amount to grams
(for example, 1 lb. equals 480 grams) : first, because the
gram is a unit of weight commonly used in dietetic calcu-
lations; second, because the fuel factors are based on the
amount of heat produced by the burning of one gram of
organic foodstuffs. Knowing the composition of food, that
is the number of hundredths of protein, carbohydrate and
fat it contains, it is a simple matter to estimate its fuel
value by multiplying the amount of each contained in one
gram by its physiological fuel factor 4.4.9. Thus if the
composition of a food is 3 3/10% protein, 4% fat and 5%
carbohydrate, one gram would contain .033 gram of pro-
tein, .04 gram of fat and 0.5 gram of carbohydrate. Hence
one gram of milk would produce
.033 X 4 = .132 calorie from protein
.04 X 9 = .36 calorie from fat
05 X 4 = .20 calorie from carbohydrate
or .692 calorie in all
But it is not necessary to estimate the fuel value of so small
a quantity as one gram, and, since the value of protein,
carbohydrates and fats is always the same it is more satis-
factory to estimate the amount of the organic constituents
contained in the entire given quantity of food, rather than
stopping to figure out the fuel value of the small quantity.
This is done by multiplying the entire number of grams
of food given by the amount of protein, fat and carbo-
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40 DIETETICS FOR NURSES
hydrate contained in one gram, then multiplying these re-
sults by the physiological fuel factor of eei/ch. Thus 100
grams of milk would yield
100 X .033 = 3.3 X 4 = 13.2 calories from protein
100 X .04 = 4.0 X 9 = 36.0 calories from fat
100 X .05 = 5.0 X 4 = 20.0 calories from carbohydrates
or a total of 69.2 calories from 100 grams of milk.
The Standard or loo Calorie Portion. — Just as it has
been more convenient to estimate a larger rather than a
smaller quantity of food material, so it is frequently more de-
sirable to estimate a hundred calories, rather than one
calorie. This is especially useful when dietaries of high
caloric (fuel) value are to be estimated, or dietaries in
which foods of like composition and fuel value are to be
interchangeable. In such cases it is a simple matter to
select the desired number of 100 calorie portions of those
foods which are to make up the dietary.*
Method of Estimating the loo Calorie Portion. — The
number of calories yielded by 100 grams of food material is
taken as a basis upon which to estimate the 100 calorie
portion, and X represents the number of grams required to
yield this portion. The problem is one of "simple propor-
tion," for example, take the 100 grams of milk just esti-
mated, we found that 100 grams (or c.c.) furnished 69.2
calories of heat, then, 100:69.2 :: X : 100— 145 or 145
grams of milk are required to furnish 100 calories of heat.
Suppose it is desirable to substitute eggs for a part of the
milk in the diet, eggs have a higher fuel value per unit of
weight than milk, their average composition being 13.4%
protein, and 10.5 7^ fat (no appreciable amount of carbohy-
drates), 100 grams of eggs would yield
100 X .134 = 13.4 X 4 = 53.6 calories from protein
100 X .105 = 10.5 X 9 = 94.5 calories from fat,
or a total of 148 calories.
•See Table of Standard or 100 Calorie Portions, in Appendix
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THE FUEL VALUE OF FOOD 41
The Standard or 100 calorie portion of eggs would be, .
100 : 148 : : X : 100 = 68
or the number of grams required to yield 100 calories.
Thus it is seen that in using the fuel value of a hundred
grams of food material for estimating the standard or 100
calories portion the extremes are always the same.
Hence, the weight of the 100 calorie portion may always
be obtained by multiplying the extremes and dividing the
result by the number of calories furnished by 100 grams of
food material.
PROBLEMS
(a) Compare the fuel value of the various common food
materials.
(b) How does the fuel value of a chicken salad compare
with that of fruit salad?
(c) Figure the fuel value of a cupful of cream of tomato
soup and compare it with that furnished by the same
quantity of beef broth.
(d) Weigh and measure a 100-calorie portion of spinach and
c(Knpare it with a 100-calorie portion of sweet potato.
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CHAPTER III
THE FOOD REQUIREMENTS OF THE BODY
The human body, as far as can be judged, does not use
one nutrient to the exclusion of another, but science has
proved that the best results are obtained from diets bal-
anced to suit the needs of the body, providing the fuel and
repair materials in the amounts which are calculated to
give the maximum value with the minimum expenditure
on the part of the organism.
For while no two individuals are exactly alike, there are
factors which govern or influence the food requirements of
all, and thus make it possible to estimate the needs of the
body with a fair degree of accuracy.
It has been found, by means of calorimeter experiments
(direct and indirect), that a certain amount of heat is pro-
duced within the body, regardless of external movement or
food; that is, when a body is lying absolutely quiet with no
movement save that of breathing, the internal work of the
organism, which is continuous, releases so much heat, and
this is produced whether there is food to replace it or
whether the body structure is burned. This is known as
the basal rate of metabolism, and constitutes the normal
basal requirements. Any external movement will increase
this rate; the greater the activity the higher the increase.
Consequently external work calls for food in addition to
that which is used to run the engine, in order to save the
body from destruction.
DuBois* finds "Basal Metabolism above normal in
exophthalmic goiter, in fevers, in lymphatic leukemia, and
* "Archives of Internal Medicine," Vol. XXVII (1916), p. 91^.
43
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FOOD REQUIREMENTS OF THE BODY 43
in pernicious anemia, in severe cardiac disease, and in
some cases of severe diabetes and cancer; it is lower than
normal in cretinism, and in myxedema, in old age, in some
wasting diseases and perhaps in some cases of obesity."
This fluctuation in the Basal Rate of metabolism furnishes
a factor in the diagnosis of disease, not only recognized but
coming more and more in use.
FACTORS DETERMINING THE FOOD REQUIREMENTS
OF THE BODY
For the Adult. — Muscular activity. Age and Size, are
most important factors influencing the food requirements.
The physical condition and environment of the individual
also exert a certain amount of influence upon the intake of
food.
Work. — Muscular activity, as already stated, increases
the body expenditures; consequently the more active the
work the greater amount of energy food needed per unit of
weight.
Age. — As the individual grows older, the rate of met-
abolism decreases until, in old age, it is not more than
a third to a fifth of what it was in earlier life. This is due
to a general "slowing down" of the machinery, the heart
does not beat so rapidly, nor is the respiration so quick.
The digestive organs, the heart, the liver, and the kidneys,
cannot handle the volume of food which was required dur-
ing the period of greatest physical activity. Hence, any
great excess over and above that which is needed for the
maintenance of the body in health will be a source of
danger to the elderly person. Von Noorden claims the
food requirements of individuals from
60 to 70 years of age to be reduced 10% ; for people from
70 to 80 years of age to be .reduced 20% ; for people from
80 to 90 years of age to be reduced 30%,
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44 DIETETICS FOR NURSES
Sex. — Science has proved, that there is little difPerence
in the food requirements of men and women, provided they
are alike in age, weight and size, and are doing the same
amount and type of work. But women, as a rule, weigh
less than men, hence their food requirements are approxi-
mately less.
Murlin finds the food requirements of pregnant women
to be some what higher than of non-pregnant ones, and
the requirements of the nursing mother to be higher than
either (see chapter on Pregnancy and Lactation).
For the Child. — The factors influencing the food re-
quirements are different, to a certain extent, from those of
the adult. The main difference lies in the fact that the
adult needs food only for the maintenance and repair of
the body, while the child must have food, not only to cover
its maintenance requirements, but to support the growth
and development which should be continuous from birth
to maturity. Resistance, too, must be developed during
this period in order to safeguard the child through life.
The rate of metabolism in the infant is greater than at
any other period of life, consequently, even if a child were
one-third the weight of its parent, it would inevitably cease
to grow and would become malnourished, if its food re-
quirements were reckoned at only one-third that of the
parent.
Adjusting the Food Requirements. — Taking these fac-
tors as guides for estimating the food requirements of man,
it is evident that no hard and fast law can be laid down to
cover all, that each individual must adjust the food intake
according to the weight and activity of the body. Sherman
has arranged the following table showing the energy ex-
penditures per hour for the average man (154 pounds), per
pound of body weight (these are approximate averages
only).
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FOOD REQUIREMENTS OF THE BODY 45
TABLE*
Sleeping quietly 60-70 calories per hour
Awake, lying still 70-86 calories per hour
Sitting at rest 100 calories per hour
Standing at rest 115 calories per hour
Tailoring 135 calories per hour
Tyi)ewriting rapidly 140 calories per hour
'iight exercise*' (stationary bicycle) . . . 170 calories per hour
Shoemaking 180 calories per hour
Walking slowly (about 2^^ miles an hour) . 200 calories per hour
Carpentry or metal work 240 calories per hour
"Active exercise" (stationary bicycle) . . 290 calories per hour
Walking briskly (about 3% miles an hour) . 300 calories per hour
Stone working 400 calories per hour
Severe exercise, such as sawing wood . . 450 calories per hour
Running (about 5V^ miles an hour) . . . 500 calories per hour
Very severe exercise (stationary bicycle) . 600 calories per hour
The above table, calculated for an average man weigh-
ing 154 pounds, may seem less simple to use than one
based on the energy requirements per pound of body weight
per hour, of an average individual. For example, a man
weighing 123 pounds and performing practically the same
amount and type of work as done by the man weighing
154 pounds would require practically one-fifth less calories
than the latter individual. Hence, to facilitate the estima-
tion of the food requirements for average individuals, the
following table is included.®
Sleeping 0.42 calorie per hour, per lb. of body wt.
Sitting at rest .... 0.65 calorie per hour, per lb. of body wt.
Light muscular exercise . 1.10 calories per hour, per lb. of body wt.
Active muscular exercise . 1.90 calories per hour, p6r lb. of body wt.
Severe muscular exercise . 3.00 calories per hour, per lb. of body wt.
Possibly a few explanatory words, as to the terms used
in the above tables, will assist the nurse in making the nec-
essary calculation. "Sleeping quietly" makes allowance
for no movement save that of respiration; any undue rest-
lessness will call for an increase in the above allowance.
■"Chemistry of Food and Nutrition," (revised), p. 186, by Henry Sher-
man.
•The Same.
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46 DIETETICS FOR NURSES
"Sitting at rest" includes the time spent at meals, sit-
ting in class room, ward office, studying or reading. It does
not include much walking about the room, rising frequently,
or nervous restlessness.
"Light exercise" includes all light house work, running
an ordinary sewing machine, walking about office or ward,
(receiving ward included). It does not include washing,
sweeping or scrubbing.
"Active exercise" includes washing, sweeping, scrub-
bing, general house work, carpentry, and such. sports as
tennis, basket ball, and ordinary gymnasium work.
"Severe exercise" includes road workers (working with
pick and shovel) fast running, baseball, football, and
swimming.
"Very severe exercise" includes the work done by
miners, handling of freight, and lumbermen, especially
those working in extreme cold, where the severe cold makes
extra demands on the fuel supply. By making use of the
averages just mentioned it should be a simple matter to
calculate the food requirements of any normal individual.
It is necessary to know the weight of the person in ques-
tion, and the manner in which the twenty-four hours are
spent, and, in the case of elderly individuals, make the re-
ductions believed to be necessary for health.
Method of Using the Tables. — Let us take a nurse in
training for this purpose. Suppose the nurse weighs 110
pounds, and spends the twenty-four hours as follows,
Sleeping 8 hours
Sitting at meals 2 hours
Studying 2 hours
In class 1 hour
On duty 9 hours
Off duty (walking briskly) 2 hours
Her daily food requirements would probably be approxi-
mately 2,235 calories. This estimate would be increased,
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FOOD REQUIREMENTS OF THE BODY 47
if she were obliged to do much heavy lifting, scrubbing of
beds, or other duties requiring the expenditure of much
effort. It would be decreased if the hours spent in study
and class room work were increased and the hours on the
ward shortened. The estimation may be made as follows,
Sleeping 8 hrs 110 X 0.42 X 8 = 370 calories
Sitting at meals 2 hrs 110 X 0.65 x 2 = 143 calories
Sitting in class 1 hr 110 X 0.65 X 1 = 71.5 calories
Studying, 2 hrs 110 X 0.65 X 2 = 143 calories
On duty 9 hrs. ...... 110 X 1.10 X 9 = 1089 calories
Off duty (walking briskly) 2 hrs. . 110 X 1.90 X 2 = 418 calories
Total for day 2234.5 calories
This estimate may be made to suit any individual, the
man in the oflBce or the one working on the streets, the
woman living at home or the one spending eight or ten
hours scrubbing the floors of a great office building; it is
simply a matter of adjusting the calories in the dietary to
meet the requirements of body weight and muscular
activity.
Energy Requirements for Children. — In estimating
the energy needs of children, the above method is not satis-
factory, since the storage of material for growth must be
considered, as well as the activities of the body. The growth
period includes the years from birth to the eighteenth year,
after which time the food requirements of the body are
made on a basis of weight and muscular activity, as in all
adults. The table on the following page shows the food
allowances made for healthy children; in the feeding of
malnourished or underweight children, more food in pro-
portion to age is given in order to overcome the handicap
under which they are suffering.
Children, like adults, differ in degrees of activity; that
is, one child may be very active, running and playing more
strenuously than another. Hence a margin of safety must
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48 DIETETICS FOR NURSES
Food Allowances for Healthy Children*
Age
Calories
PER Day
YeatB
Boys
Qirls
Under 2
900-1200
900-1200
2- 3
1000-1300
980-1280
a-4
1100-1400
1060-1360
4- 5
1200-1500
1140-1440
6- 6
1300-1600
1220-1520
6-7
1400-1700
1300-1600
7- 8
1600-1800
1380-1680
8- 9
1600-1900
1460-1760
9-10
1700-2000
1550-1850
10-11
1900-2200
1650-1950
11-12
2100-2400
1750-2050
12-13
2300-2700
1850-2150
13-14
2500-2900
1950-2250
14-15
2600-3100
2050-2350
15-16
2700-3300
2150-2450
16-17
2700-3400
2250-2500
Calories per Pound of Body Weight per Day.*
Years
Calories per pound, per day
Under 1 year
45
1- 2
40-43
3- 4
37^0
4- 6
37^0
6- 6
36-37
6-7
34r^6
7-8
32-34
8-9
30-35
9-10
30-35
10-11
28-32
11-12
28-32
12-13
28-32
13-14
25-30
14-16
20-25
15-16
20-25
16-17
20-25
After which time the food requirements are based on degree of mus-
cular activity, boys and girls of seventeen years and over requiring
as much food as men and women.
*GiIIett, Al.C.P.of N. Y.
•Table compiled from material in "Feeding the Family," by Rose.
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FOOD REQUIREMENTS OF THE BODY 40