CHAPTER VIII_The nutrition of man

PRACTICAL APPLICATIONS WITH SOME ADDITIONAL DATA

TOPICS: Proper application of the results of scientific research

helpful to mankind. Dietary habits should be brought into conformity

with the true needs of the body. The peculiar position of proteid

foods emphasized. The evil effects of overeating. What the new

dietary standards really involve. The actual amounts of foodstuffs

required. Relation of nutritive value to cost of foods. The

advantages of simplicity in diet. A sample dietary for a man of

70 kilograms body-weight. A new method of indicating food values.

Moderation in the daily dietary leads toward vegetable foods. The

experiments of Dr. Neumann. The value of fruits as food. The merits

of animal and vegetable proteids considered in relation to the

bacterial processes in the intestine. A notable case of simplicity

in diet. Intelligent modification of diet to the temporary needs of

the body. Diet in summer and winter contrasted. Value of greater

protection to the kidneys. Conclusion.

Knowledge has value in proportion to the benefit it confers, directly

or indirectly, on the human race. Every new scientific fact or

principle brought to light promises help in the understanding of

Nature’s laws, and when rightly interpreted and properly applied is

sure to aid in the advancement and prosperity of the individual and of

the community. Proper methods of living, economical adjustment of the

intake to the varying needs of the body, avoidance of excessive waste

of foodstuffs and of energy, are all desirable precepts, which rational

people presumably are inclined to follow so far as their knowledge and

understanding of the subject will permit. Here, as elsewhere, false

teaching may be exceedingly mischievous and lead to costly errors;

while blind reliance upon customs, instinct, and superstitions is

hardly in keeping with twentieth-century progress.

Modern scientific methods should give us help in dietetics, as in

other branches of hygiene and practical medicine. A few short years

ago, diphtheria was a scourge which brought misery to many a home,

for there was at hand no adequate means of combating the disease; but

scientific research has given us new light, and placed at our command a

weapon of inestimable value. Do we hesitate to use it when the occasion

arises, because it happens to be out of keeping with old-time customs

and traditions? No, we recognize the possibility of help, and as the

need is urgent we turn to it quickly, with hope and thankfulness that

scientific progress has opened up a pathway of escape from a threatened

calamity.

Not many years ago we drank freely of such water as was at hand,

without realization of danger from bacteria or disease germs, looking

on epidemics of typhoid fever perhaps as a visitation of Divine

Providence, in punishment of our many sins and to be borne meekly and

with resignation. But all this has changed through the researches of

bacteriologists and chemists; scientific facts of the utmost importance

have been clearly established; a classification of water-borne

diseases has been adopted, and we realize fully that diseases of this

order can be kept from our doors by proper precautions applied to

our water supply. To-day, epidemics of typhoid fever are traceable

solely to the ignorance or carelessness of the individual or of the

commonwealth, and the exemption which we of the present generation

have from this class of diseases is directly due to the application of

precautionary measures based on the information furnished by scientific

investigation. It is proper for us to use caution in the acceptance of

new ideas, but not that form of caution which refuses change on the

ground that what has been is sufficiently good for the present and the

future. The point of view is ever changing with advance of knowledge,

and it is not profitable to exclude opportunities for improvement

in personal hygiene and general good health, any more than in other

matters that affect the prosperity of the individual or the community.

Dietary habits should be brought into conformity with the true needs of

the body. Excessive consumption of proteid food, especially, should be

avoided on the ground that it is not only unnecessary and wasteful, but

is liable to bring penalties of its own, most undesirable and wholly

uncalled for. We may, perhaps, accept these statements at their full

value, and yet have a shadow of doubt in our minds as to whether, after

all, dietary customs do not harmonize sufficiently at least with true

nutritive requirements. All the data that we have presented in the

preceding chapters, however, have seemingly given a positive answer to

such doubts, and indicate quite clearly that the results of scientific

study are opposed to the prevailing dietary standards, especially

as regards proteid food. As the celebrated physiologist Bunge has

expressed it, “The necessity for a daily consumption of 100 grams of

proteid is incomprehensible, so long as we do not know of any function

of the body in the performance of which the chemical potential energies

of the destroyed proteid are used up.”

Perfectly trustworthy evidence is at hand showing that the needs of

the body for potential energy can be fully met, and indeed are more

advantageously met, by the non-nitrogenous foods, carbohydrates and

fats. The energy of muscle work, as we have seen, comes preferably

from the breaking down of non-nitrogenous material, so that there is

no special call for proteid in connection with increased muscular

activity. In fact, it would appear that the need for proteid food

by man is limited to the requirements of growth and development,

reinforced by the amount called for in that form of tissue exchange

which we have emphasized under the term “endogenous proteid

metabolism,” or true tissue metabolism. To be sure, there must be a

certain reserve of proteid, available in case of emergency, but this is

easily established without resorting to excessive feeding.

The peculiar position which proteid foods occupy in man’s dietary

naturally make them the central figure, around which the other foods

are grouped. No other form of food can take the place of proteid; a

certain amount is needed each day to make good the loss of tissue

material broken down in endogenous katabolism, and consequently our

choice and combination of the varied articles of diet made use of

should be regulated by the amount of proteid they contain. But while

proteid foods occupy this commanding position, it is not necessary

or desirable that they should exceed the other foodstuffs in amount,

or indeed approach them in quantity. We must be ever mindful of

the fact, so many times expressed, that proteid does not undergo

complete oxidation in the body to simple gaseous products like the

non-nitrogenous foods, but that there is left behind a residue of

non-combustible matter--solid oxidation products--which are not

so easily disposed of. In the forceful language of another, “The

combustion of proteid within the organism yields a solid ash which must

be raked down by the liver and thrown out by the kidneys. Now when

this task gets to be over-laborious, the laborers are likely to go on

strike. The grate, then, is not properly raked; clinkers form, and

slowly the smothered fire glows dull and dies” (Curtis).

Even though no such dire fate overtakes one, the penalties of excessive

proteid consumption are found in many ills, for which perhaps the

victim seeks in vain a logical explanation; gastro-intestinal

disturbance, indigestion, intestinal toxæmia, liver troubles, bilious

attacks, gout, rheumatism, to say nothing of many other ailments,

some more and some less serious, are associated with the habitual

overeating of proteid food. But excessive food consumption is by no

means confined to the proteid foodstuffs; general overfeeding is a

widespread evil, the marks of which are to be detected on all sides,

and in no uncertain fashion. One of the most common signs of excessive

food consumption is the tendency toward obesity, a condition which

is distinctly undesirable and may prove decidedly injurious. Undue

accumulation of fat is not only a mechanical obstacle to the proper

activity of the body as a whole, but it interferes with the freedom

of movement of such muscular organs as the heart and stomach, thereby

interposing obstacles to the normal action of these structures.

Further, whenever undue fat formation is going on in the body, there is

the ever present danger that the lifeless fat may replace the living

protoplasm of the tissue cells and so give rise to a condition known as

“fatty degeneration.” While a superabundance of fat in the body is a

sure telltale of overeating, the absence of obesity is by no means an

indication that excess of food is being avoided. There is here, in man

as in animal kind, much idiosyncrasy; some persons, especially those

endowed with a long and large frame, tend to keep thin even though

they eat excessively, while others grow fat much more readily. As a

well-known physician has expressed it, “In the one case, the subject

burns, instantly and mercilessly, every stick of fuel delivered at his

door, whether or not he needs the resulting hot fire roaring within,

while the other, miser-like, hoards the rest in vast piles, filling the

house from cellar to garret.”

Temperance in diet, like temperance in other matters, leads to good

results, and our physiological evidence points out plainly, like

a signpost all can read, that there is no demand on the part of

the body for such quantities of food as custom and habit call for.

Healthfulness and longevity are the prizes awarded for the successful

pursuance of a temperate life, modelled in conformity with Nature’s

laws. Intemperance, on the other hand, in diet as in other matters,

is equally liable to be followed by disaster. A physician of many

years’ experience, with opportunities for observation among different

classes of people, has written, “that overeating tends to shrink the

span of life in proportion as it expands the liver is demonstrable

both directly and indirectly. Let any actuary of life-insurance be

asked his experience with heavy-weight risks, where the waist measures

more than the chest, and the long-drawn face of the businessman, at

memory of lost dollars, will make answer without need of words. Then

let be noted the physique of the blessed ones that attain to green old

age, and, in nine cases out of ten, spry old boys--no disparagement,

but all honor in the phrase--will be found to be modelled after the

type of octogenarian Bryant or nonogenarian Bancroft--the whitefaced,

wiry, and spare, as contrasted with the red-faced, the pursy, and the

stout. It is true, as has already been mentioned, that in old age

much of an adventitious obesity is absorbed and disappears, but the

Bryant-Bancroft type is that of a subject who never has been fat at

all. And just such is preëminently the type that rides easily past the

fourscore mark, reins well in hand, and good for many another lap in

the race of life.”[76]

[76] Edward Curtis, M.D.: Nature and Health, p. 70. Henry Holt &

Company, New York, 1906.

With these thoughts before us, we may consider briefly just what is

involved in these new dietary standards that aim to conform more

closely with actual body needs. Referring at first to proteid food, it

may be wise to again emphasize the fact that the weight of the body,

_i. e._, the weight of the proteid-containing tissues, as contrasted

with excessive fat accumulation, is one of the important factors not to

be overlooked when determining the dietary needs of a given individual.

As must be perfectly clear, from all that has been said, the man of

170 pounds’ body-weight has more proteid tissue to nourish than the

man of 130 pounds’ weight, and consequently what will satisfy the

requirements of the latter individual will not suffice for the former.

We must understand distinctly that no general statement can be made

applicable to mankind at large, but due consideration must be given to

the size and weight of the individual structure. We have found that

the average need for proteid food by adults is fully met by a daily

metabolism equal to an exchange of 0.12 gram of nitrogen per kilogram

of body-weight. This means a katabolism of three-fourths of a gram of

proteid matter daily, per kilogram.

Remembering, however, that the intake of proteid food must be somewhat

in excess of the actual proteid katabolism, since not all of the

proteid of the food is available, and as this is a variable amount

depending upon the proportion of animal and vegetable foods with their

different degrees of digestibility and availability, we may place the

required intake of proteid at 0.85 gram per kilogram of body-weight,

still keeping to maximum figures for safety’s sake. Hence, for a man

weighing 70 kilograms or 154 pounds, there would be required daily

59.5 grams--say 60 grams--of proteid food to meet the needs of the

body. These are perfectly trustworthy figures, with a reasonable margin

of safety, and carrying perfect assurance of being really more than

sufficient to meet the true wants of the body; adequate to supply all

physiological demands for reserve proteid, and able to cope with the

erratic requirements of personal idiosyncrasies. It will be observed

that such an intake of proteid food daily is equal to one-half the Voit

standard for a man of this weight, while it is still further below the

Atwater standard and far below the common practices of the majority of

mankind in Europe and America, as indicated by the published dietary

studies.

It may not be out of place to state at this point that in the writer’s

opinion the use of the terms “standard diet” and “dietary standards,”

etc., is objectionable, since such usage seems to demand a certain

degree of definiteness in the daily diet for which there is no

justification. As in the use of the term “normal diet,” there is danger

of misinterpretation, and of the assumption that dietary habits should

be regulated strictly in accord with certain set principles. This I

believe to be altogether wrong; there should be, on the contrary,

full latitude for individual freedom, but freedom governed by an

intelligence that appreciates the significance of scientific fact

and is willing to mould custom and habit into accord with them. What

is needed to-day is not so much an acceptance of the view that man

requires daily 0.85 gram of proteid per kilogram of body-weight, as a

full appreciation of the general principle, which our definite figures

have helped to work out, that the requirements of the body for proteid

food are far below the customary habits of mankind, and that there is

both economy and gain in various directions to be derived by following

the general precepts which this view leads to. In other words, there

is no advantage, but, on the contrary, much bother and worriment, in

attempting to follow out in practice the details of our more or less

exact physiological experiments.

The general teaching which they afford, however, can be adopted and

put in practice in our daily lives, without striving to follow too

closely the so-called standards which our experiments have led to.

Again, the sample dietaries adopted in our experiments have no special

virtue, aside from the general principle they teach that simple foods

are quite adequate for the nourishment of the body, and that the amount

of nitrogen or proteid they contain was sufficient to meet the demands

of the particular individuals consuming it. Broadening intelligence on

matters of food composition is called for on all sides, and as this

is acquired together with due appreciation of the relative nutritive

values of proteid, fat, and carbohydrate, there is placed at our

command the power of intelligent discrimination, with the ability

to apply the principles set forth in our own way, in harmony with

personal likes and dislikes.

To the majority of us, not very familiar with the percentage

composition of ordinary food materials, and unaccustomed to the

weighing of food in grams, the figures given from time to time may

have failed to convey a very definite impression regarding the actual

amounts of the various foods made use of. Further, our ideas concerning

the bulk of many of the common articles of food necessary to furnish

the 60 grams of proteid required daily by a man of 70 kilograms

body-weight may be somewhat hazy. The following table, however, will be

of service in this direction:

SIXTY GRAMS OF PROTEID ARE CONTAINED IN

Fuel Value[77]

One-half pound fresh lean beef, loin 308 calories

Nine hens’ eggs 720

Four-fifths pound sweetbread 660

Three-fourths pound fresh liver 432

Seven-eighths pound lean smoked bacon 1820

Three-fourths pound halibut steak 423

One-half pound salt codfish, boneless 245

Two-and one-fifth pounds oysters, solid 506

One-half pound American pale cheese 1027

Four pounds whole milk (two quarts) 1300

Five-sixths pound uncooked oatmeal 1550

One and one-fourth pounds shredded wheat 2125

One pound uncooked macaroni 1665

One and one-third pounds white wheat bread 1520

One and one-fourth pounds crackers 2381

One and two-thirds pounds flaked rice 2807

Three-fifths pound dried beans 963

One and seven-eighths pounds baked beans 1125

One-half pound dried peas 827

One and eleven-twelfths pounds potato chips 5128

Two-thirds pound almonds 2020

Two-fifths pound pine nuts, pignolias 1138

One and two-fifths pounds peanuts 3584

Ten pounds bananas, edible portion 4600

Ten pounds grapes 4500

Eleven pounds lettuce 990

Fifteen pounds prunes 5550

Thirty-three pounds apples 9570

[77] Fuel value of the quantity needed to furnish the sixty grams of

proteid.

The figures in this table are instructive in many ways. First, it is

to be noted that the daily proteid requirement of sixty grams can

be obtained from one-half pound of lean meat (uncooked), of which

the loin steak is a type. Subject to some variations in content of

water, an equivalent weight of lean flesh of any variety, lamb, veal,

poultry, etc., will furnish approximately the same amount of proteid.

With fish, such as halibut steak, and with liver, three-quarters of a

pound are required; while with sweetbreads, four-fifths of a pound are

needed to furnish the requisite amount of proteid. Of salt codfish,

one-half pound will provide the same amount of proteid as an equivalent

weight of fresh beef; while with lean smoked bacon the amount rises

to seven-eighths of a pound. Among the vegetable products, it is to

be observed that dried peas and beans, almonds and pine nuts, are as

rich in proteid as the above-mentioned animal foods, essentially the

same weights being called for to provide the daily requirement of

proteid. The same is true of cheese, the variety designated having such

a composition that one-half pound is the equivalent, so far as the

content of proteid is concerned, of a like amount of fresh beef. We

must not be unmindful of the fact previously mentioned, however, that

there are differences in digestibility among these various foodstuffs

which tend to lower somewhat the availability of the vegetable

products, also of the cheese, thereby necessitating a slight increase

in the amount of these foods required to equal the value to the body of

lean meat.

Secondly, passing to the other extreme in our list, we find indicated

types of foods exceedingly poor in proteid, such as the fruits;

notably, bananas, grapes, prunes, apples, etc., also lettuce, and in

less degree potatoes. These are the kinds of food that may legitimately

attract by their palatability, but do not add materially to our intake

of proteid even when consumed in relatively large amounts. Thirdly, we

see clearly indicated a radical difference between the animal foods

and those of vegetable origin, in that with the former the fuel value

of the quantity necessary to furnish the sixty grams of proteid is

very small, as compared with a like amount of the average vegetable

product. One-half pound of lean meat, for example, with its 60 grams of

proteid, has a fuel value of only 308 calories, while two-thirds of a

pound of almonds has a fuel value of 2020 calories, and one-half pound

of dried peas 827 calories. Naturally, this is mainly a question of

the proportion of fat or oil present. With fat meat, as in bacon, the

calorific value rises in proportion to increase in the amount of fat,

the proteid decreasing in greater or less measure.

The main point to be emphasized in this connection, however, is that a

high proteid animal food, like lean meat, eggs, fish, etc., obviously

cannot alone serve as an advantageous food for man. We see at once the

philosophy of a mixed diet. Let us assume that our average man of 70

kilograms body-weight needs daily 2800 calories. On this assumption,

if he were to depend entirely upon lean beef for his sustenance, he

would require daily four and a half pounds of such meat, which amount

would furnish nine times the quantity of proteid needed by his system.

The same would be more or less true of other kindred animal products.

On the other hand, certain vegetable foods on our list, such as flaked

rice, crackers, and shredded wheat, contain proteid, with carbohydrate

and fat, in such proportion that the energy requirement would be met

essentially by the same quantity as served to furnish the necessary

proteid. Passing to the other extreme among the vegetable products, as

in potatoes and bananas, for example, we find fuel value predominating

largely over proteid content. The ideal diet, however, is found in a

judicious admixture of foodstuffs of both animal and vegetable origin.

Wheat bread, reinforced by a little butter or fat bacon to add to its

calorific value, shredded wheat with rich cream, crackers with cheese,

bread and milk, eggs with bacon, meat with potatoes, etc.; the common,

every-day household admixtures, provide combinations which can easily

be made to accord with true physiological requirements. The same may be

equally true of the more complicated dishes evolved by the high art of

modern cookery.

Lastly, our table throws light upon certain questions of household

economy. The cost of foods is regulated mainly not by the value of the

nutrients contained therein, but by other factors of quite a different

nature. Relationship between supply and demand naturally counts here

as in other directions, but our demand is liable to be based not upon

food values, but rather upon delicacy of flavor, palatability, and

other kindred fancies, some real and some imaginary. Ordinary crackers

can be purchased for ten cents a pound, but if we desire a little

stronger flavor of salt and a special box to hold them, we pay eighteen

cents a pound. Rolled very thin and thus made more delicate, they cost

twenty-five cents, while sold under a special name and perhaps tied

with a blue ribbon they cost thirty-five cents a pound. Their nutritive

value per pound is the same in all cases, but we pay something for

the increased labor of preparation and a good deal for the added

attractiveness to eye and palate. We pay twenty-two cents a pound for

round steak, thirty-two cents for loin steak, and seventy-five cents a

pound for sweetbreads, the high price of the latter being regulated by

the relative scarcity of the article and not by its food value. As our

table indicates, the real value of sweetbread as a source of proteid

is only a little more than half that of lean beef. Its fuel value,

however, is somewhat more than that of beef, but a little fat added

to the latter will more than compensate and at a trifling cost. When

we can afford it, we pay the increased price for sweetbreads simply

because their delicacy and flavor are attractive to us. We should

not do it under the mistaken idea that we are indulging in a highly

nutritive article of food, for as a matter of fact it is not only less

nutritive than a corresponding weight of lean beef, but in addition

it possesses certain qualities, in its high purin-content, that are a

menace to good health if indulged in too freely.

Where expense must be carefully guarded, or where the condition of the

family purse is such that conflicting demands must be intelligently

considered in order to insure wise expenditure and the greatest

permanent good of the many, it is well to remember that price is no

guarantee whatever of real nutritive value. Two quarts of milk will

furnish half the daily fuel requirement of our average man and the

entire proteid requirement, while its cost is only sixteen cents.

Reinforced by a pound loaf of wheat bread, the energy requirement for

the day would be fully met, with surplus nitrogen to store up for

future needs, and at an additional cost of only ten cents. A mixture in

this proportion, however, would not be strictly physiological, since

it is wasteful of proteid, but it may serve to illustrate the point.

A better illustration is found in an admixture, quite adequate to

supply the daily needs of our average man, both for proteid and energy,

composed of one-quarter of a pound of lean beef, two-thirds of a pound

of bread, and half a pound of butter, and at a total cost not to exceed

thirty cents. The contrast of such prices with what is so commonly

paid for table delicacies is somewhat striking; it could be made still

more so by drawing upon many common vegetable foods, rich alike in

proteid and in fuel value, the cost of which is even less than the

simple food mixtures just referred to. It is not necessary, however, to

enlarge upon this question; it is sufficient to merely emphasize the

fact that the exaggerated demand of our present generation for dietetic

luxuries is leading us far away from the proverbially simple life of

our forefathers, and without adding in any way to the effectiveness of

the daily diet. On the contrary, it is in part responsible for the high

proteid consumption of the present day, with its attendant evils, and

involves a large and unnecessary expenditure without adequate return.

The wants of the body for food are far more advantageously met by a

simple dietary, moderate in amount and at an expense comparatively

slight.

A recent writer,[78] in the “British Medical Journal,” a practitioner

of medicine in the Highlands of Scotland, has said that these are

“facts of common experience in the Highlands of Scotland, and probably

among the peasantry of other countries also, where the old beliefs and

customs have not too readily given way to the luxuries of civilization.

Oatmeal in one form or another is a daily ingredient in the diet of a

Highland peasant. The potato also is a staple food, and is consumed in

large quantities with salt herring or other fish, and perhaps in some

cases salt mutton or pork. Milk and eggs are used by most. The growing

consumption of tea, however, and the increasing relish for sweets,

candy, pastry, and biscuits, threaten to destroy the old way of living.

A typical day’s diet for a crofter or fisherman who still believes in

the traditional diet would be somewhat like this:

Breakfast.--Oatmeal porridge or brose with milk; bread, butter, and tea.

Dinner.--Potatoes galore and herrings, or other salt fish.

Supper.--Porridge and milk, or oat bread and cheese, and tea.

[78] Aran Coirce: British Medical Journal, April 7, 1906, p. 829.

“I have often been assured by shepherds that they could work all

day ‘on the hill’ after a breakfast of oatmeal brose and milk,

without fatigue and without feeling hungry, returning in the evening

to partake of a dish of broth, potatoes, and salt mutton. In these

diets, proteid forms a very small proportion, and yet a hardier race

than these shepherds and fishermen cannot be found.” It should be

added that “brose” consists of a few handfuls of oatmeal, to which

is added boiling water, the mixture being stirred vigorously and

placed for a few minutes near the fire. It is then eaten with milk, or

better, with cream. In the absence of positive data, it can only be

asserted that the above dietary stands for simplicity and frugality.

Its proteid-content may be low, but the amount of proteid taken per

day by these Highlanders will obviously depend upon the _quantity_

of food consumed. Oatmeal is fairly rich in proteid, and it is quite

conceivable that the amount eaten daily may be such as to result in a

high proteid exchange.

It will be profitable for us to gain, if possible, a fairly clear idea

of the quantities of food requisite for our average man of 70 kilograms

body-weight; _i. e._, the amounts necessary to provide 60 grams of

proteid and 2800 calories. With this end in view, we may outline a

simple dietary, expressed in terms that will convey a clear impression,

showing what may be eaten without overstepping the required limits of

proteid or total calories:

BREAKFAST

Proteid Calories

One shredded wheat biscuit 3.15 grams 106

30 grams

One teacup of cream 3.12 206

120 grams

One German water roll 5.07 165

57 grams

Two one-inch cubes of butter 0.38 284

38 grams

Three-fourths cup of coffee 0.26 ...

100 grams

One-fourth teacup of cream 0.78 51

30 grams

One lump of sugar ... 88

10 grams ----- ---

12.76 850

LUNCH

Proteid Calories

One teacup homemade chicken soup 5.25 grams 60

144 grams

One Parker-house roll 3.38 110

38 grams

Two one-inch cubes of butter 0.38 284

38 grams

One slice lean bacon 2.14 65

10 grams

One small baked potato 1.53 55

2 ounces, 60 grams

One rice croquette 3.42 150

90 grams

Two ounces maple syrup ... 166

60 grams

One cup of tea with one slice lemon ... ..

One lump of sugar ... 38

10 grams ----- ---

16.10 928

DINNER

Proteid Calories

One teacup cream of corn soup 3.25 72

130 grams

One Parker-house roll 3.38 110

38 grams

One-inch cube of butter 0.19 142

19 grams

One small lamb chop, broiled 8.51 92

lean meat, 30 grams

One teacup of mashed potato 3.34 175

167 grams

Apple-celery lettuce salad with mayonnaise dressing 0.62 75

50 grams

One Boston cracker, split 1.32 47

2 inches diameter, 12 grams

One-half inch cube American cheese 3.35 50

12 grams

One-half teacup of bread pudding 5.25 150

85 grams

One demi-tasse coffee ... ..

One lump of sugar ... 38

10 grams ----- ---

29.21 951

The grand totals for the day, with this dietary, amount to 58.07 grams

of proteid and 2729 calories. It is of course understood that these

figures are to be considered as only approximately correct, but the

illustration will suffice, perhaps, to give a clearer understanding of

the actual quantities of food involved in a daily ration approaching

the requirements for a man of 70 kilograms body-weight. Further, there

may be suggested by the figures given for proteid and fuel value of

the different quantities of foods, a clearer conception of how much

given dietary articles count for in swelling the total values of a

day’s intake. Moreover, it is easy to see how the diet can be added to

or modified in a given direction. If a little more proteid is desired

without changing materially the fuel value of the food a boiled egg can

be added to the breakfast, for example. An average-sized egg (of 53

grams) contains 6.9 grams of proteid, while it will increase the fuel

value of the food by only 80 calories. Or, if more vegetable proteid is

wished for, a soup of split-peas can be introduced, without changing

in any degree the calorific value of the diet. Thus, one teacup of

split-pea soup (144 grams) contains 8.64 grams of proteid, while the

fuel value of this quantity may be only 94 calories. The addition of

one banana (160 grams) will increase fuel value 153 calories, but will

add only 2.28 grams of proteid. If it is desired to increase fuel

value without change in the proteid-content of the food, recourse can

always be had to butter, fat of meat, additional oil in salads, or to

syrup and sugar.

Such a menu as is roughly outlined, however, has perhaps special value

in emphasizing how largely the proteid intake is increased by foods

other than meats, and which are not conspicuously rich in proteid

matter. All wheat products, for example, while abounding in starch,

still show a large proportion of proteid. Thus, shredded wheat biscuit

(1 ounce), which is a type of many kindred wheat preparations, from

bread and biscuit to the various so-called breakfast foods, yields

about 3 grams of proteid per ounce and approximately 100 calories.

Even potato, which is conspicuously a carbohydrate food owing to its

large content of starch, yields of nitrogen the equivalent of at least

three-fourths of a gram of proteid per ounce. If larger volume is

desired without much increase in real food value, there are always

available green foods, such as lettuce, celery, greens of various

sorts, fruits, such as apples, grapes, oranges, etc. Too great reliance

on meats as a type of concentrated food, on the other hand, augments

largely the intake of proteid, and adds a relatively small amount to

the fuel value of the day’s ration.

An ingenious method of indicating food values, which promises to

be of service in sanatoria and under other conditions where it is

desirable to record or correct the diet of a large number of persons,

has been devised recently by Professor Fisher.[79] The method aims to

save labor, and is likewise designed to visualize the magnitude and

proportions of the diet. The food is measured by calories instead of

by weight, a “standard portion” of 100 large calories being the unit

made use of. In carrying out the method, foods are served at table in

“standard portions,” or multiples thereof. In the words of Fisher, the

amount of milk served, for example, “instead of being a whole number of

ounces, should be 4.9 ounces--the amount that contains 100 calories.

This ‘standard portion’ constitutes about two-thirds of an ordinary

glass of milk. Of the 100 calories which it contains 19 will be in the

form of proteid, 52 in fat, and 29 in carbohydrate.” In the carrying

out of this plan, it is evident that the weight of any food yielding

100 calories becomes a measure of the degree of concentration. From

the standpoint of fuel value, olive oil is probably one of the most

concentrated of foods, approximately one-third of an ounce containing

100 calories. The following table, taken from Fisher’s description

of his method, will serve to show the amounts of several foods

constituting a “standard portion,” and also the number of calories in

the form of proteid, fat, and carbohydrate:

[79] Irving Fisher: A new method for indicating food values. American

Journal of Physiology, vol. 15, p. 417, 1906.

+-----------------------+-------------+--------+--------+--------+--------+

+-----------------------+------+------+--------+--------+--------+--------+

|Almonds, a dozen | 0.53 | 15 | 13.0 | 77.0 | 10 | 100 |

|Bananas, one large | 3.50 | 98 | 5.0 | 5.0 | 90 | 100 |

|Bread, a large slice | 1.30 | 37 | 13.0 | 6.0 | 81 | 100 |

|Butter, an ordinary pat| 0.44 | 13 | 0.5 | 99.5 | .. | 100 |

|Eggs, one large | 2.10 | 60 | 32.0 | 68.0 | .. | 100 |

|Oysters, a dozen | 6.80 | 190 | 49.0 | 22.0 | 29 | 100 |

|Potatoes, one | 3.60 | 100 | 10.0 | 1.0 | 89 | 100 |

| two-thirds glass | 4.90 | 140 | 19.0 | 52.0 | 29 | 100 |

| a small piece | 1.40 | 40 | 31.0 | 69.0 | .. | 100 |

|Sugar, five teaspoons | 0.86 | 24 | .... | .... | 100 | 100 |

+-----------------------+------+------+--------+--------+--------+--------+

Obviously, to make use of the “calories per cent” method a table such

as the above, covering all common foodstuffs and showing the weight of

each food constituting a standard portion, together with the calories

of proteid, fat, and carbohydrate in this portion, is necessary. The

chief advantage of the method, however, is that it lends itself readily

to geometrical representation and affords an easy means of determining

the constituents of combinations of different foods by use of a simple

mechanism, for a description of which reference must be made to the

original paper.

Any attempt to follow a daily routine which accords with the true

needs of the body leads necessarily toward foods derived from the

plant kingdom, with the adoption of simple dietary habits, and with

greater freedom from the exciting influence of the richer animal

foods. There is, however, virtue in a simple dietary that appeals and

satisfies, and in so doing testifies to the completeness with which

it meets the physiological requirements of the body. A physician,[80]

writing in the “British Medical Journal,” says: “I determined to give

the minimum-of-proteid diet a fair trial in my own case. The result

was that I was relieved of a life-long tendency to acid dyspepsia and

occasional sick headache; my fitness for work, my appetite and relish

for food, were increased, without any diminution, but rather a slight

increase, in my weight. My practice extends over a wide area of rough

mountainous country involving long journeys on cycle, on foot, driving,

and in open boats, in fair and foul weather. The muscular exertion

and endurance necessary for the work would seem to require a large

proportion of proteid and a generous diet altogether, but since I began

to experiment I have suffered less than formerly from fatigue, and seem

to eat in all a smaller quantity of food. My diet consists of:

[80] Aran Coirce: British Medical Journal, April 7, 1906, p. 829.

Breakfast, 8.30 A.M.--Oatmeal cakes, bread and butter, about 1 cubic

inch of cheese or bloater paste, marmalade, and one breakfast cup of

tea.

Lunch, 1.30 P.M.--Same as breakfast, with occasionally a boiled egg,

and sometimes coffee instead of tea.

Dinner, 7 P.M.--Thick soup containing vegetables, with bread,

followed by suet pudding or fruit tart; or vegetable stew, containing

2 or 3 ounces of meat, with boiled potatoes, followed by milk pudding

and jam, and occasionally a cup of black coffee.”

This statement of personal experience is in close accord with

statements that have come to the writer in hundreds of letters during

the past two or three years, from persons who have for some reason

chosen to follow a more abstemious mode of life. Such testimony has a

certain measure of value in that it offers corroborative evidence of

the beneficial effects of a moderate diet, more closely in accord with

the actual demands of the body for food. It does not, however, carry

quite that degree of assurance that scientific evidence, gathered by

careful observers and controlled by weights and measures that hold the

imagination in check, affords; and so we may turn to a different type

of testimony, presented in an elaborate research by Dr. Neumann,[81]

of the Hygienic Institute at Kiel, an experiment on himself extending

through a total of 746 days.

[81] Dr. med. et phil. R. O. Neumann: Experimentelle Beiträge zur

Lehre von dem täglichen Nahrungsbedarf des Menschen unter besonderer

Berücksichtigung der notwendigen Eiweissmenge. Archiv für Hygiene,

Band 45, p. 1, 1902.

The experiment was divided into three periods. In the first period of

ten months the subject, with a body-weight of 66.5 kilograms, consumed

daily on an average the amounts of food indicated in the following

table. In this same table are also included the daily values, based on

the preceding data, for a body-weight of 70 kilograms. Thirdly, the

table likewise shows the amounts of utilizable food contained in the

foodstuffs actually eaten, on the basis of 70 kilos body-weight.

AVERAGE DAILY FOOD FOR TEN MONTHS

+------------+-----------------+----------------+-----------------+

+------------+-----------------+----------------+-----------------+

|Fat | 83.5 | 90.2 | 81.2 |

|Carbohydrate| 230.0 | 242.0 | 225.0 |

|Alcohol | 43.7 | 45.6 | 41.0 |

+------------+-----------------+----------------+-----------------+

During this period of ten months, the body-weight of the subject

remained practically constant, or indeed showed a slight gain up to 67

kilograms. All the functions of the body, and the general condition

of good health, were in no wise impaired; so that in the words of the

subject, the amount of food eaten must have been sufficient for the

needs of the body. Somewhat striking is the fact that of the 2309

calories in the daily food, more than one-fourth was derived from the

beer consumed daily (1200 c.c.). Also noticeable is the relatively

small amount of carbohydrate taken daily, only about one-half the

quantity designated by Voit as the average requirement of German

laborers. Finally, it is to be observed that during this period of

ten months, the daily consumption of food as calculated for a man of

70 kilograms body-weight, based on the actual food consumption of the

subject with a weight of 66.5 kilos, was not widely different from our

own statement of 60 grams of proteid and 2800 calories. The tendency,

however, in Dr. Neumann’s experiment was toward lower fuel values and

somewhat higher proteid consumption.

In a second period of 50 days, with a slightly larger daily intake,

Dr. Neumann observed that his body was laying by nitrogen, _i. e._,

storing up proteid on a daily diet of 76.5 grams of proteid and with

sufficient fat and carbohydrate to furnish a total fuel value of 2658

calories. In the final period of 8 months, the following data were

obtained:

AVERAGE DAILY FOOD FOR EIGHT MONTHS

+------------+-----------------+----------------+-----------------+

+------------+-----------------+----------------+-----------------+

|Fat | 109.0 | 106.1 | 95.5 |

|Carbohydrate| 168.9 | 164.2 | 152.7 |

|Alcohol | 5.5 | 5.3 | 4.7 |

+------------+-----------------+----------------+-----------------+

During this period, it is to be noted that the fuel value of the

day’s food averaged only 2057 calories, which for a body-weight of

70 kilograms would amount to less than 2000 calories. The proteid

consumption, however, was larger than we have found to be necessary

for a man of the above weight. Still, the facts are in harmony with

the general principle that there is no necessity for a daily intake

of food such as common usage dictates, there being obviously a wide

difference between a minimal daily consumption of 118 grams of proteid

and 3000 or more calories, such as is assumed to be needed by a man of

70 kilos, and 74 grams of proteid with 1999 calories. Under the latter

conditions, the subject gained a kilogram in weight during the eight

months, while the establishment of nitrogen equilibrium testifies to

the now generally accepted view that it is quite possible for the body

to establish nitrogen equilibrium at different levels, _i. e._, with

different quantities of proteid food and different fuel values.

The diet made use of by Neumann was a mixed one, containing a great

variety of animal and vegetable foods, but withal simple and moderate

in quantity. Calculated per kilogram of body-weight, the average

consumption of food material per day during the three periods was as

indicated in the following table:

DAILY FOOD CONSUMPTION PER KILOGRAM OF WEIGHT

+-------------+--------+-----+-------------+--------+--------+

+-------------+--------+-----+-------------+--------+--------+

|First Period | 0.99 | 1.3 | 34.5 | 0.56 | 34.7 |

|Second Period| 1.10 | 2.3 | 33.4 | . . | 59.7 |

|Third Period | 1.00 | 1.5 | 23.4 | 0.07 | 28.5 |

+-------------+--------+-----+-------------+--------+--------+

The average of daily food consumption for the total of 746 days was as

follows: 74.2 grams proteid, 117 grams fat, 213 grams carbohydrate, and

2367 calories. On such a diet, during this long period, equilibrium was

satisfactorily maintained, thereby furnishing additional evidence that

quantities of food way below the so-called normal amounts are quite

adequate to meet the needs of the body. There is no conflict whatever

between these results and our own; they both point in the same general

direction. Perhaps the one thing that needs to be again emphasized,

however, in view of the low fuel values used by Neumann, is that while

they proved quite adequate in his case, the demand in this direction is

governed largely by the degree of bodily activity. In fact, Neumann’s

results with fuel values are in perfect harmony with the data obtained

by us with professional men, but the writer is inclined to believe that

for the majority of mankind, with the varying degrees of activity and

muscular exertion called for, a somewhat larger number of heat units is

desirable, and indeed on many occasions demanded.

Still, it is perfectly obvious that custom has greatly exaggerated

the fuel values required in ordinary muscular work, and such results

as are here presented tend to emphasize the true relationship between

actual requirements and fuel intake. Further, it must not be overlooked

that the rate of proteid katabolism is governed in large measure by the

amount of non-nitrogenous food, and consequently a too narrow margin in

the consumption of the latter will obviously result in a higher rate

of proteid exchange. We are inclined to the belief that a satisfactory

degree of bodily efficiency is more liable to be maintained with a

somewhat larger consumption of carbohydrate food, combined with a

reduction in proteid food to a level nearer our own figures. It will

be observed that the average amount of carbohydrate taken daily by

Neumann, during the 746 days, was only 213 grams, while the daily

consumption of fat averaged 117 grams. These figures are interesting

and instructive in many ways, especially as indicating the ease with

which the body accommodates itself to a relatively low intake of

proteid food, combined with a small proportion of starches and sugars.

This relationship between carbohydrate and fat might well occur at

times as a natural result of personal taste, but as a general rule it

is probably better, from the standpoint of digestibility and general

availability, for the daily food to contain a larger proportion of

carbohydrate.

Under this head, I would lay special stress upon the value to the

body of the natural sugars as well as of starch. We are inclined to

deprecate the widespread use of candy, especially among children, and

there is no doubt that the too lavish use of sugar in such concentrated

form does at times do harm; but when eaten as an integral part of the

many available fruits its use cannot be too highly lauded, for both

young and old. Oranges, grapes, prunes, dates, plums, and bananas are

especially to be commended, and in lesser degree peaches, apricots,

pears, apples, figs, strawberries, raspberries, and blueberries. In

all of these fruits, it is the sugar especially that gives food value

to the article, while the mild acids and other extractives, together

with the water of the fruit, help in other ways in the maintenance

of good health. Where personal taste and inclination are favorably

disposed, the first six fruits named can be partaken of freely, and the

diet of the young, especially, can be advantageously modified by the

liberal use of such articles of food.

Of the other fruits, apples when thoroughly ripe are above reproach

if properly masticated, but the raw fruit is somewhat indigestible

when swallowed in too large pieces, and may cause trouble to a

delicate stomach. A baked apple, on the other hand, is both savory and

wholesome, and if served with sugar and cream, for example, constitutes

a most healthful and satisfying article of food. Peaches, apricots,

and strawberries as ripe fruits are likewise exceedingly valuable, but

here personal idiosyncrasy frequently comes to the fore, especially

with strawberries, and prohibits their free use. The peculiar acidity

of these latter fruits is occasionally a source of trouble, which

leads to their avoidance; but this is far less liable to happen with

people living on a low proteid diet with its greater freedom from purin

derivatives, or uric acid antecedents. Further, there is a tendency

on the part of some individuals to suffer from acid fermentation with

too liberal use of starches and sugar, but as a rule the advantages

of ordinary starchy and natural sugar-containing foods cannot be

overestimated. It is certainly wise to give them a conspicuous place in

the daily dietary and to encourage their use, especially by children.

As has been stated in several connections, a diet which conforms to the

true nutritive requirements of the body must necessarily lead toward

vegetable foods. In no other satisfactory way can excess of proteid be

avoided, and at the same time the proper calorific value be obtained.

This, however, does not mean vegetarianism, but simply a greater

reliance upon foods from the plant kingdom, with a corresponding

diminution in the typical animal foods. This raises the question of the

possible relation of diet to the bacterial processes of the intestine,

knowing, as we do, that the latter are of primary importance in the

causation of certain forms of auto-intoxication, etc. Recent studies

have indicated that the bacterial flora of carnivorous animals is

quite different from that of herbivorous animals, and this being so,

it is easy to see how a predominance of vegetable or animal food may

modify the bacterial conditions of the intestinal tract in man. Dr.

Herter[82] has reported the presence in the intestines of cats, dogs,

tigers, lion, and wolf of many spore-holding bacilli, as well as free

spores and vegetative forms of anærobic organisms; some of which at

least are decidedly pathogenic when injected into the subcutaneous

connective tissue, leading to serious and even fatal results within

twenty-four hours. With herbivorous animals, on the other hand, such as

the buffalo, goat, horse, elephant, etc., the predominating organisms

are of a different order from those found in the intestines of the

carnivora; proving practically non-pathogenic, or only slightly so,

when injected subcutaneously, and less disposed to produce putrefactive

changes or other chemical decompositions.

[82] C. A. Herter: Character of the Bacterial Flora of Carnivorous

and Herbivorous Animals. Science, December 28, 1906, p. 859.

In the words of Dr. Herter, “These differences in the appearance

and behavior of the bacteria derived from typical carnivora and

herbivora suggest that the habit of living upon a diet consisting

exclusively of raw meat entails differences in the types of bacteria

that characterize the contents of the large intestine. The occurrence

of considerable numbers of spore-bearing organisms in the carnivora

points to the presence of anærobic putrefactive forms in great

numbers. The results of subcutaneous inoculations into guinea-pigs

bear out this view and indicate that the numbers of organisms capable

of producing a hemorrhagic œdema with tissue necrosis, with or without

gas-production, are very considerable.... The observations recorded are

of much interest in relation to the bacterial processes and nutrition

of herbivorous as distinguished from carnivorous animals, and are

significant furthermore for the interpretation of bacterial conditions

found in man. The question arises whether the abundant use of meat over

a long period of time may not favor the development of much larger

numbers of spore-bearing putrefactive anærobes in the intestinal tract

than would be the case were a different type of proteid substituted for

meat.” While it may be said truly that observations of this character

are as yet not sufficiently numerous or conclusive to warrant positive

or sweeping statements, yet there is a suggestion here well worthy of

thoughtful consideration in its general bearing on the nutrition of

mankind.

Simplicity in diet, with or without complete abstinence from meat,

is often resorted to as a means of relief from bodily ailments, and

such cases sometimes afford striking illustrations of the adequacy

and benefits of a relatively low intake of food. Cases of this sort,

perhaps, are more frequently observed among elderly people, where the

daily requirements are not so great as with younger and more active

persons, but they offer evidence in support of our main thesis that

dietary habits are no guarantee of bodily requirements. I have in mind

the details of an exceedingly interesting case reported with much care

by Dr. Fenger;[83] the case of a man who at 61 years of age, after a

long period of poor health, brought himself quickly into a condition of

sound health by a daily diet characterized by extreme simplicity and

with an exceedingly low fuel value. The daily diet made use of during

the fifteen years the subject was under examination consisted of the

following articles:

[83] Dr. S. Fenger: Beiträge zur Kenntniss des Stoffwechsels im

Greisenalter. Skandinavisches Archiv für Physiologie, Band 16, p.

222, 1904.

1889–1892: 1 egg, 1 quart of oatmeal soup, 2 quarts of skim milk,

1-1/2 ounces of red wine, 1/4 ounce of sugar.

1892–1894: 2 eggs, 1 quart of oatmeal soup, 2 quarts of skim milk,

1-1/2 ounces of red wine, 1/4 ounce of sugar.

1894–1900: 3 eggs, 1 pint of oatmeal soup, 2 quarts of skim milk,

1-1/2 ounces of red wine, 1/4 ounce of sugar, 2 ounces of plum and

raspberry juice.

1900–1903: 3 eggs, 1 pint of barley soup, 3 pints of sweet milk, 1

pint of buttermilk, 1-1/2 ounces of red wine, 1/4 ounce of sugar, 2

ounces of plum and raspberry juice.

It will be observed that during these fifteen years the subject

partook of no meat whatever, and further, that the diet was wholly

in fluid form. At the close of this long period, the subject, being

then 75 years of age, was reported as well and in good health, with

satisfactory physical condition for a person of his years. He was a

man of small body-weight, only 42 kilograms, but during this period

of voluntary restriction in diet, he suffered no loss. It is perhaps

worthy of comment also that all through this lengthy period no salt

was taken other than what was naturally present in the simple foods

made use of. The point to attract our attention especially, however, is

that for fifteen years, during which the quality and quantity of this

man’s food was carefully observed, body-weight, general good health,

and physical vigor were all maintained, together with freedom from the

ills of previous years and with a daily diet characterized by extreme

simplicity. The chemical composition of the diet was likewise peculiar,

particularly in its exceedingly low fuel value. The following table

shows the amounts of proteid, fat, and carbohydrate consumed daily

during the four periods designated:

+---------+--------+-----+--------+---------+---------+---------+

| Period. |Proteid.|Fat. |hydrate.|Calories.| per | per |

+---------+--------+-----+--------+---------+---------+---------+

|1889–1892| 79.8 | 21.7| 152.0 | 1125 | 26 | 1.90 |

|1892–1894| 85.2 | 27.0| 152.0 | 1200 | 28 | 2.03 |

|1894–1900| 87.0 | 30.1| 150.1 | 1230 | 29 | 2.07 |

|1900–1903| 84.4 | 73.7| 148.3 | 1600 | 38 | 2.00 |

+---------+--------+-----+--------+---------+---------+---------+

Especially noticeable here is the low intake of fat and carbohydrate,

with the corresponding low fuel value, and also the relatively high

consumption of proteid, averaging 2.0 grams daily per kilogram of

body-weight. Dr. Fenger concludes that for a man of this age and

weight, with the relative inactivity characteristic of old age, a heat

value in the intake of 30 calories per kilogram of body-weight is quite

sufficient for the needs of the body. This may be quite true, but to

maintain nitrogen equilibrium under such conditions requires a larger

intake of proteid food than is desirable. It will be observed that in

the last period of four years a very decided change in the diet was

instituted; proteid was diminished somewhat, but the noticeable change

was the decided increase in fat, produced in large measure by the

substitution of whole milk, with its contained cream, for skim milk. In

the words of Dr. Fenger, this change was necessitated by the appearance

of gout in the subject. From superficial examination of the dietary of

the preceding eleven years there would seem no occasion for criticising

the subject for high living, and yet I believe we are quite within the

limits of reason in saying that the proteid exchange for a subject of

this body-weight was altogether too high. The heat requirements of the

body were being met in an unnecessarily large degree from the breaking

down of proteid material, with consequent formation of excessive

nitrogenous waste, among which uric acid was plainly conspicuous.

One comment to be made here is that meat and other rich

purin-containing foodstuffs are not the only source of gout and uric

acid. Excessive proteid katabolism, both exogenous and endogenous, is

a possible source of danger in this respect, and the above subject,

though living on an exceptionally simple diet, was consuming far more

proteid per kilogram of body-weight than was necessary or desirable.

Increase of fatty food naturally served to diminish the rate of proteid

katabolism, and this could have been advantageously accompanied by

a still greater reduction in the amount of proteid ingested, and a

larger addition of non-nitrogenous foodstuffs. In old age, there is

naturally a slowing down of the metabolic processes, and both nitrogen

equilibrium and body equilibrium can be satisfactorily maintained by a

relatively small intake of food and with gain to the body; but there

is every reason to believe that economy in proteid food can be more

advantageously adopted than economy in non-nitrogenous foodstuffs.

Finally, we may call attention to the many possibilities of an

intelligent modification of the daily diet to the temporary needs

of the individual. The season of the year, summer and winter, the

climate, the degree of activity of the body, the state of health,

temporary ailments, etc., all present special conditions which admit

of particular dietetic treatment. In hot summer weather, for example,

there is plainly less need for food than in the cold winter season,

especially for fat with its high calorific value. During the cold part

of the year, the lower temperature of the surrounding air, with the

tendency toward greater muscular activity, calls for more extensive

chemical decomposition in order to meet the demand for heat, and the

energy of muscular contraction. There is perhaps no special reason for

any material change in the amount of proteid food consumed in the two

seasons, except in so far as it may seem desirable at times to take

advantage of the well-known stimulating properties of proteid to whip

up the general metabolism of the body, in harmony with the principle

that all metabolic processes may need spurring to meet the demands of a

greatly lowered temperature in the surrounding air.

Fuel value, however, should be increased somewhat during the winter

months in our climate. Fat promises the largest amount of energy,

but there is more of a tendency to store up excess of fat than of

carbohydrate, hence the latter foods have certain advantages as a

source of the additional energy needed during cold weather. In warm

weather, it should be our aim to diminish unnecessary heat production

as much as possible, though it must be remembered that the body is

to be maintained approximately at least in equilibrium, and this

calls for an adequate amount of food. Lighter foods, however, may be

advantageously employed, such as fruits, vegetables, fresh fish, etc.

Fats and fat meats especially are to be avoided, not only because

there is no specific need for them, but particularly on account of a

greater sensitiveness of the gastro-intestinal tract during the hot

seasons of the year, that is liable to result in a disturbance whenever

undue quantity of rich or heavy food is taken. Further, in hot summer

weather we may advantageously live more largely on foods served cold,

and thereby avoid the heat ordinarily introduced into the body by

hot fluids and solids. These, however, are all obvious physiological

truths, constituting a form of physiological good sense the application

of which calls for no special expert knowledge.

Less obvious, though no less important, is the partial protection

that can be afforded to weakened or disabled kidneys by judgment and

discrimination in the matter of diet. In acute or chronic nephritis,

forms of so-called Bright’s disease, is there not danger of overtaxing

organs already weakened by placing upon them the daily duty of

excreting large amounts of solid nitrogenous waste, as well as of the

various inorganic salts which are so intimately associated with many of

the organic foodstuffs? The consumption of excessive and unnecessary

amounts of proteid food simply means the ultimate formation of just

so much more urea, uric acid, etc., which must be passed out through

the kidneys. In the words of Bunge, “There is no organ in our body so

mercilessly ill treated as the kidneys. The stomach reacts against

overloading. The kidneys are obliged to let everything pass through

them, and the harm done to them is not felt till it is too late to

avoid the evil consequences.” It would seem the part of wisdom,

therefore, to adjust the daily intake of proteid food to as low a

level as is consistent with the true needs of the body, in those cases

where the kidneys are at all enfeebled, or where it seems desirable to

exercise due precaution as a possible means of prevention.

Equal care is frequently called for in connection with the mineral

matters which enter so largely into many natural foodstuffs, or which

are introduced as condiments. As an illustration, we may note one or

two peculiarities in the distribution of sodium and potassium salts

in the tissues of the body. Potassium is an indispensable constituent

of every living cell, and the latter has the power of absorbing and

holding on to such amounts of this particular element as may be

necessary for the functional activity of the tissue of which it is a

part. Sodium, on the other hand, stands in a different relationship

to living structures. It is widely distributed, but in the higher

animals, as in man, sodium salts are most abundant in the fluids of

the body, notably in the plasma of the blood. Herbivorous animals have

a strong liking for sodium chloride or common salt, but this is not

true of carnivorous animals; indeed, the latter animals have a great

dislike for salty articles of food. Vegetable products are all rich in

potassium salts, whereas ordinary animal foods, such as meat, eggs,

milk, and blood, are relatively poor in this element.

It is claimed that the abundance of potassium salts in vegetable foods

is the cause of the apparent need for sodium chloride by herbivorous

animals, and in lesser degree by man. This is explained by supposing

that when the salts of potassium reach the blood by absorption of the

vegetable foods, an interchange takes place with the sodium chloride

of the blood plasma. “Chloride of potassium and the sodium salt of the

acid which was combined with the potassium are formed. Instead of the

chloride of sodium, therefore, the blood now contains another sodium

salt, which did not form part of the normal composition of the blood,

or at any rate not in so large a proportion. A foreign constituent

or an excess of a normal constituent, _i. e._, sodium carbonate,

has arisen in the blood. But the kidneys possess the function of

maintaining the same composition of the blood, and of thus eliminating

every abnormal constituent and any excess of a normal constituent. The

sodium salt formed is therefore ejected by the kidneys, together with

the chloride of potassium, and the blood becomes poorer in chlorine

and sodium. Common salt is therefore withdrawn from the organism by

the ingestion of potassium salts. This loss can only be made up from

without, and this explains the fact that animals which live on a diet

rich in potassium, have a longing for salt” (Bunge). It is certainly a

fact worthy of note that man takes only one salt as such in addition

to those that are naturally present in his food, and it is equally

significant that sodium chloride is by no means lacking in ordinary

foodstuffs. If the individual lives entirely on animal foods, he has no

desire for salt, but as soon as he adopts a vegetable diet the craving

for salt shows itself. Vegetable foods, however, are not all alike in

their content of potassium salts; some, like rice, contain relatively

little, while others, like potatoes, peas, and beans, are comparatively

rich in this element.

We may recognize in these statements a physiological demand for a

certain amount of salt, especially when vegetable foods enter into

the daily dietary, but there is no justification for the employment

of such quantities as are generally made use of. Where the vegetable

food is largely rice, a small fraction of a gram of salt is really

sufficient for all physiological purposes; and in those cases where

ordinary cereals, legumes, potatoes, etc., constitute the chief part

of the dietary, a few grams of salt, at the most, will suffice to meet

the daily needs. Common usage, however, frequently raises the amount

consumed to 25 grams or more per day, the bulk of which is at once

eliminated through the kidneys; thereby entailing a certain amount

of renal activity, which must, it would seem, constitute something

of a strain upon organs ordinarily hard worked at the best. “Do we

not impose too great a task upon them, and may it not be fraught

with serious consequences? When on a diet of meat and bread, without

salt, we excrete not more than from 6 to 8 grams of alkaline salts

in twenty-four hours. With a diet of potatoes, and a corresponding

addition of salt, over 100 grams of alkaline salts pass through the

kidneys in the day. May not there be danger in this? The habit of

drinking spirituous liquors, which moreover is reckoned one of the

causes of chronic nephritis, also brings about the immoderate use of

salt, and thus one sin against nature leads to another” (Bunge).

The moral we would draw (from these observations) is that in weakened

conditions of the kidneys there is reason in reducing the rate of

proteid exchange to the lowest level consistent with the maintenance

of equilibrium and the preservation of strength and vigor, thereby

diminishing the amount of nitrogenous waste to be eliminated and the

consequent strain upon these organs. Further, there is suggested

moderation in the amount of salt to be used daily, and some

circumspection in the amount and quality of vegetable foods consumed

in order to regulate more effectually the quantity of saline waste to

be handled by the kidneys. These conclusions are just as worthy of

consideration as the more obvious rule that in diabetes or glycosuria

proper precaution must be observed in the eating of carbohydrate

foods. In gout and rheumatism, accumulated physiological knowledge

teaches plainly the necessity of avoiding those foods that are rich in

purin-containing compounds. Uric acid owes its origin in part at least

to substances of this class; and as an ounce of prevention is worth

more than a pound of cure, we may by proper moderation in the use of

such foods save ourselves from the disagreeable effects of accumulated

uric acid deposits.

In conclusion, the nutrition of man, if it is to be carried out by the

individual in a manner adapted to obtaining the best results, involves

an intelligent appreciation of the needs of the body under different

conditions of life, and a willingness to accept and put in practice the

principles that scientific research has brought to light, even though

such principles stand opposed to old-time traditions and customs. The

master words which promise help in the carrying out of an intelligent

plan of living are moderation and simplicity; moderation in the amount

of food consumed daily, simplicity in the character of the dietary, in

harmony with the old saying that man _eats to live_ and not lives to

eat. In so doing there is promise of health, strength, and longevity,

with increased efficiency, as the reward of obedience to Nature’s

laws.

INDEX

Abderhalden, Emil, 35

Absorption, a physiological process, 41

diffusion as a factor in, 41

from the stomach, 31

in intestine, 37

of fats, 43, 49

of fats, in dogs on low proteid diet, 233, 261

of food products, by blood, 44

of peptones, 41

of proteid in dogs on low proteid diet, 233, 262

of proteid products, 47

of proteoses, 41

osmosis, as factor in, 41

paths of, 44

reconstruction of proteid during, 42

selective action, of sugars, 47

Acid, aspartic, 34, 67, 259

glutaminic, 34, 259

hydrochloric, 25, 26

uric, 73

uric, excretion of, as influenced by diet, 144

Acids, amino, 34

diamino, 34

Adenase, 71

Adenin, 72

Aldehydase, 64

Amino acids, 34, 67

Ammonia, 70, 259

Amylopsin, 32

Anabolism, 50

Animals, influence of low proteid diet on high proteid, 231, 233, 243

Animal starch, _see_ Glycogen

Appetite, in relation to food requirements, 162

Arginin, 34, 68, 70, 259

Argutinsky, views on muscle work, 123

Aspartic acid, 34, 67, 259

Assimilation limits of sugars, 47

Athlete, photograph of, 190

Athletes, fuel value of food of, on low proteid diet, 198

strength tests of, on low proteid diet, 206

true proteid requirement of, 186

Atwater and Benedict, 109, 111

Autodigestion (_see_ Autolysis), 63

Autolysis, 12

Availability, of foods, 12

of carbohydrates, as source of energy, 45

Bacterial flora in intestine, of carnivora, 292

of herbivora, 292

Bacterial processes in intestine, in relation to food, 292

Balance, nutritive, as affected by various factors, 117, 118

Basal energy exchange, 104

Beaumont, William, on movements of stomach, 27

Benedict, F. G., _see_ Atwater and Benedict

Bergell and Lewin, 36

Beriberi, and diet, 224

Blood, absorption of food products by, 44

behavior of disaccharides when introduced into, 39

effects of injection of proteoses and peptones into, 41

relation of sugar in, to glycogen, 46

sugar in, 45

Body, amounts of food required to furnish proteid needs of, 274

efficiency of, as a machine, 111

equilibrium, 78

nature of oxidation in the, 60

needs of nitrogen by, 4

needs for food by, 169

needs and dietary habits, 268

needs of proteid by, 268, 272

relation of oxygen to decompositions in, 61

resistance, _see_ Resistance

sample dietary supplying needs of, 280

site of oxidation in, 62

surface, relation to energy exchange, 104, 105

surface, relation to nitrogen requirement in dogs, 248

Body-weight, on low proteid diet, 175, 181, 185, 190, 199, 245–255

relation to proteid requirement, 184, 188, 198, 227

Bright’s disease, _see_ Nephritis

Breisacher, L., on minimum proteid requirement, 172

Bunge, 124

Calorie, 14

Calorimeter, respiration, 102

Cane sugar, assimilation limit of, 47

behavior when introduced into blood, 39

utilization of, 40

Cannon, W. B., on muscular movements of stomach, 28, 29

Carbon dioxide, output in rest, 111, 112

dioxide, output during work, 111, 123

equilibrium, 84

excretion, during fasting, 84

moiety of proteid, 129

Carnivora, bacterial flora in intestine of, 292

Carbohydrates, as food, 6

as fuel, 6

as heat producers, 58

as proteid sparers, 92

as source of energy, 128

as source of energy in fasting, 81

as source of energy in work, 58

availability of, 13

availability of, as source of energy, 45

composition of, 5

formation from proteid, 129

fuel value of, 15

in foodstuffs, 7

liver as regulator of, 45

respiratory quotient of, 107

Casein, cleavage products of, 70

Caspari and Glässner, on minimum proteid requirement in man, 172

Cellulose, in vegetables, influence on digestion, 263

Chemical character of proteid, influence on nutrition, 256

composition of foodstuffs, 7

Circulating proteid, 134

Clapp, S. H.

(_see_ Osborne and Clapp, on proteid cleavage products), 258

Cleavage, oxidative, 61

Climbing, oxygen consumption in, 116

Cogan, Thomas, on temperance in food, 166

Cohnheim, Otto, on proteid decomposition, 36

Composition, of proteid, 3

of carbohydrate, 5

of fat, 6

Cornaro, Louis, on temperance in food, 168

Cost of foods in relation to nutritive value, 277

Creatin, 74

Creatinin, 74

excretion, as influenced by diet, 144

Curtis, Edward, Nature and Health, 2, 5, 214

Dapper, Max, 99

Dangers of underfeeding, 214

Degeneration, fatty, 270

Deuteroproteose, 67, 69

Dextrins, 21, 37

Dextrose, 37

assimilation, limit of, 47

utilization of, 40

Diabetes, phloridzin, 130

Diamino acids, 34

Diet, and beriberi, 224

and renal activity, 297

effects of exclusive proteid, upon rats, 239

effects of intemperance in, 270

effects of rice, on rats, 240

fat absorption in dogs on low proteid, 233, 261

influence of, on creatin in excretion, 144

exclusive proteid, on progeny in rats, 240

on growth in rats, 239

monotony in, 242

on oxygen consumption in man at rest, 126

on oxygen consumption in man at work, 126

on respiratory quotient in man at rest, 126

on respiratory quotient in man at work, 126

rice, on growth in rats, 240

on urea excretion, 144

on uric acid excretion, 144

vegetable, upon dogs, 254, 256

in relation to nephritis, 297

in relation to nitrogen distribution in urine, 144

in relation to seasons of the year, 296

of Highlanders, 279

low proteid, influence on body-weight in dogs, 245, 249, 250,

251, 252, 255

nitrogen excretion during severe work on exclusive proteid, 123, 124

philosophy of a mixed, 92, 276

relation of endurance to low proteid, 210, 212

relation of inorganic salts to, 299, 300

relation of work to, 126

relation of vegetable food to low proteid, 291

sample, of soldiers, 194

sample, in experiments on true proteid requirement in man, 178,

182, 189, 195

simplicity in, advantages of, 279, 293

temperance in, 270

utilization of fat in dogs on low proteid, 261

utilization of nitrogen in dogs on low proteid, 262

variety in, 229, 242

Diets, normal, _see_ Standard diets

standard, 155

Dietary habits, in relation to needs of body, 268

of fruitarians, 215

of Japanese, 225

sample, supplying needs of body, 280

standards, use of the term, 272

Dietetic customs of mankind, 154

Dietetics, habit in, 159

Diffusion, as factor in absorption, 41

Digestibility, _see_ Availability

Digestion, gastric, of proteids, 26

importance of gastric, 30

influence of cellulose in vegetables on, 263

in the stomach, 25

object of gastric, 30

of fat, in intestine, 36

of fat, in stomach, 36

of starch, 21

products of pancreatic, of fats, 36

products of pancreatic, of proteids, 34, 67

products of pancreatic, of starch, 37

products of salivary, 21

salivary, in stomach, 23

Digestive products, reconstruction of proteid from, 42

Disease, relation of excessive proteid consumption to, 269

Dogs, effects of low proteid diet on, 232–236, 245–255

fasting experiments on, 82

fat absorption in, on low proteid diet, 233, 261

fuel value requirement of, 234, 236, 245–255

influence of low proteid diet upon body-weight in, 245–255

influence of vegetable diet on, 254, 256

nitrogen requirement of, 234, 235, 236, 245–255

photographs of, 248

proteid absorption in, on low proteid diet, 233, 262

proteid requirement, experiments by Munk, 232

proteid requirement, experiments by Rosenheim, 234

proteid requirement, experiments by Jägerroos, 236

proteid requirement, experiments by author, 243

utilization of fat in, on low proteid diet, 261

utilization of nitrogen in, on low proteid diet, 262

Disaccharides, utilization of, 40

Edestin, cleavage products of, 70

Efficiency of body, as a machine, 111

Egg albumin, cleavage products of, 70

Endogenous metabolism, 145, 146

Endurance, relation of, to low proteid diet, 210, 212

Energy, availability of carbohydrates, as source of, 45

basal exchange, 104

carbohydrate as source of, 128

carbohydrate as source of, in fasting, 81

conservation of, in man, 103

exchange, effect of muscular work, 109, 110, 113, 115

exchange, factors modifying, 105, 106

exchange, in relation to work, 119

exchange proportional to body surface, 104, 105

fat as source of, 128

fat as source of, in fasting 81

foods as source of, 15

metabolism of, in man, 103

of muscle contraction, 121

origin of, in fasting, 81

output, in man, 103

produced by man, 106

proteid as source of, 122, 123, 124, 129

proteid as source of, in fasting, 81

source of, in body, 21, 121

source of, during fasting, in work, 125

Enterokinase, 33

Enzymes, deamidizing, 71, 72

in gastric juice, 25

in pancreatic juice, 32

in saliva, 20

intracellular, 63, 71, 72, 75

reversible action of, 21

specificity of, 21

Equilibrium, carbon, 84

nitrogenous, 78

of body, 78

Erepsin, 34

Exchange, basal energy, 104

of energy, as affected by work, 109, 110, 113, 115, 119

of energy, factors modifying, 105, 106

of energy, relation to body surface, 104, 105

Exogenous metabolism, 145, 146

Fasting, carbohydrates as source of energy in, 81

excretion of carbon during, 84

excretion of nitrogen during, 80, 82, 84

experiments on dogs, 82

experiments on man, 80, 84

fat as source of energy in, 81

fuel value during, 86

fuel value of fat, metabolized during, 86

metabolism of fat during, 84

nitrogen excretion during, 80, 82, 84

origin of energy in, 81

proteid as source of energy in, 81

proteid metabolism during, 83

relation of nitrogen excretion to work during, 125

source of energy for work during, 125

Fat, absorption, 43, 49

absorption in dogs on low proteid diet, 233, 261

as food, 6

as fuel, 6

as source of energy, 128

as source of energy during work, 58

as source of energy in fasting, 81

composition of, 6

digestion of, in intestine, 36

digestion of, in stomach, 36

fuel value of, 15

fuel value of, metabolized during fasting, 86

hydrolysis of, 36

influence of feeding, on body fat, 44

in foodstuffs, 7

laying on of, from overfeeding, 98, 99

metabolism during fasting, 84, 86

respiratory quotient of, 107

saponification of, 36

specificity of body, 44

synthesis of, 43

utilization of, in dogs on low proteid diet, 261

Fats, availability of, 13

as heat producers, 58

as proteid sparers, 92

Fatty degeneration, 270

Fatigue, relation to low proteid diet, 208

Fenger, S., 293

Fick and Wislicenus, on source of muscular energy, 121

Fischer, Emil, 21

Fisher, Irving, on endurance and low proteid diet, 210

on method of indicating food values, 283

Folin, Otto, theory of proteid metabolism, 144

Food, absorption and utilization of, in dogs on low proteid diet, 261, 262

amounts, required for proteid needs of body, 274

as fuel, 6

as source of energy, 15

availability of, 12

carbohydrates as, 6

character of, in relation to bacterial processes in intestine, 292

consumption and obesity, 270

consumption, relation to prosperity, 160

fats as, 6

fuel value of, 274

of fruitarians, 217

in experiments on proteid requirement, athletes, 198

in experiments on proteid requirement, professional men, 178, 180, 185

in experiments on proteid requirement, soldiers, 198

of Japanese, 219, 221

fuel value requirement of, in dogs, 234, 236, 245–255

influence of, on respiratory quotient, 107

needs of body for, 169

of man, 2

proteids as, 3, 5

real need of body for proteid, 272

relation of appetite to, 162

relation of nutritive value and cost of, 277

requirements, factors modifying, 165

temperance in, 166, 168

value of fruits as, 290

values of, method of indicating, 283

Foods, respiratory, 58

time, remain in stomach, 29, 30

Foodstuffs, carbohydrate in, 7

composition of, 7

fat in, 7

fuel value of, 7

inorganic salts in, 7

organic, 3

plastic, 58

proteid in, 7

water in, 7

Fritz, photograph of, 199

Fruitarians, dietary of, 215

fuel value of food of, 217

proteid consumption of, 217

Fruits, value of, as food, 290

Fuel, carbohydrate as, 6

fat as, 6

proteid as, 6

Fuel value, in fasting, 86

of carbohydrate, 15

of fat, 15

of fat metabolized during fasting, 86

of food, in experiments on proteid requirement, athletes, 188

of food, in experiments on proteid requirement, professional men,

178, 180, 185

of food, in experiments on proteid requirement, soldiers, 198

of food of fruitarians, 217

of food of Japanese, 219, 221

of foods, 274

of foodstuffs, 7

of proteid, 15

of proteid metabolized during fasting, 86

requirement in the dog, experiments by Munk, 234

requirement in the dog, experiments by Rosenheim, 236

requirement in the dog, experiments by Jägerroos, 236

requirement in the dog, experiments by author, 245–255

Gastric digestion, importance of, 30

object of, 30

products of, 26

Gastric juice, action on milk, 26

composition of, 25, 26

functions of, 25, 27

hydrochloric acid in, 25, 26

influence of diet upon flow of, 25

pepsin in, 25

psychical stimulation of, 24

Gastric secretion, 24

Gelatin, as food, 4, 5

Glässner, _see_ Caspari and Glässner

Gliadin, cleavage products of, 70, 259

Glutaminic acid, 34, 67, 70, 259

Glutenin, cleavage products of, 259

Glycerin, 36

Glycocoll, 67

Glycogen, formation from proteid, 130

in liver, 46

relation to sugar of blood, 46

Growth, influence of diet on, in rats, 239

Guanase, 71

Guanin, 72

Habit, in dietetics, 159

Heat, furnished by fats and carbohydrates, 58

production during sleep, 104, 105

production in work, 110

Herbivora, bacterial flora in intestine of, 292

Herter, C. A., on bacterial flora, 292

Hirschfeld, Felix, on minimum proteid requirement, 170

Histidin, 34, 68, 70

Hofmeister, Franz, on sugar assimilation, 47

Hunt, Reid, on low proteid diet and body resistance, 226

Hunter, Andrew, _see_ Watson and Hunter

Hydrochloric acid, in gastric juice, 25, 26

Hydrolysis, of fats, 36

Hypoxanthin, 72

Indol, 37

Inorganic salts, and renal activity, 298, 300

in foodstuffs, 7

in nutrition, 2

relation to diet, 299, 300

Intemperance in diet, effects of, 270

Intermediary metabolism, _see_ Exogenous metabolism

Intestine, absorption in, 37

chemical changes in, 33

putrefaction in, 37

bacterial flora of, 292

Invertase, 40

Jägerroos, B. H., on proteid requirement in the dog, 236

Japanese Army and Navy, rations of, 224

Japanese, dietary of, 225

fuel value of food of, 219, 221

proteid consumption by, 219, 221

Katabolism, 50

nature of proteid, 75

oxygen in, 62

relation to intracellular enzymes, 75

Klemperer, on proteid requirement, 171

Lactase, 40

Lavoisier, views on oxidation, 56

Leucin, 34, 67, 70, 259

Leucosin, cleavage products of, 259

Levulose, assimilation limits of, 47

Lewin, _see_ Bergell and Lewin

Liebig, views on oxidation, 57, 120

Lipase, 32

Lipolysis, by pancreatic juice, 36

Liver, function of, as regulator of carbohydrate, 45

glycogen in, 46

synthesis of proteid by, 48

Luxus consumption, of proteid, 59

Lüthje, 101

Lymphatics, absorption of food products by, 44

Lysin, 34, 68, 70, 259

Maltose, 21, 37

behavior when introduced into blood, 39

Man, conservation of energy in, 103

energy produced by, 106

experiments on oxygen consumption in, 126

fasting experiments on, 80, 84

food of, 2

metabolism of energy in, 103

minimum proteid requirement in, 170, 171, 172, 174–208

work experiments on, 110–116

Mastication, importance of, 23

Meat, influence on growth in rats, 239

Metabolic changes as influencing respiratory quotient, 108

Metabolism, 51

and old age, 296

endogenous, 145

exogenous, 145

Folin’s theory of proteid, 144

influence of proteid on, 83

influence of carbohydrates on proteid, 92, 94, 95, 96, 97

influence of fat on proteid, 92, 93, 96, 97

influence of proteid on proteid, 88

of energy in man, 103

of fat during fasting, 84, 86

oxidation in, 60

of proteid during fasting, 83, 86

Pflüger’s theory of proteid, 138

processes of, 51

significance of exogenous and endogenous proteid, 49

significance of proteid, 131

Voit’s theory of proteid, 134

Methyl glycocoll, _see_ Sarcosin

Methyl guanidin, 74

Milk sugar, assimilation limit of, 47

behavior when introduced into blood, 39

utilization of, 40

Mineral matter, _see_ Inorganic salts

Minimum proteid requirement, 59

Mixed diet, philosophy of a, 92, 276

Monotony of diet, influence of, 242

Morphotic proteid, 134

Munk, Immanuel, on proteid requirement in the dog, 232

Muscular movements of stomach, 27–30

Needs of body for food, 169

Nephritis, in relation to diet, 297

Neumann, R. O., on low proteid diet, 286

Nitrogen, distribution of, in the urine in relation to diet, 144

needs by body, 4

utilization of, in dogs on low proteid diet, 262

Nitrogen excretion, as influenced by proteid, 59, 87, 90

during fasting, 80, 84

during work in fasting, 125

during excessive work, 114, 127

during hard work on proteid diet, 123, 124

in experiments on proteid requirement, in dogs, 245, 249, 250, 251,

252, 255

in experiments on true proteid requirement, athletes, 187, 188

in experiments on true proteid requirement, professional men, 176,

177, 181, 185

in experiments on true proteid requirement, soldiers, 199, 200, 201

relation to work, 122, 123, 124

Nitrogen equilibrium, on low proteid diet, 176, 177, 181, 188, 200,

201, 249, 250, 251, 252, 255

Nitrogen requirement, in dogs, 234–236, 245–255

in man, 180, 184, 185, 187, 198, 227

relation to body-weight, 184, 248

Nitrogenous equilibrium, 78

Nitrogenous metabolism, theory of Folin, 144

theory of Pflüger, 138

theory of Voit, 134

Normal diets, 155

Nutrition, factors in, 16, 17

influence of chemical character of proteid on, 256

inorganic salts, as aids in, 2

physiological economy in, 264

purpose of, 2

Nutritive balance, as affected by various factors, 117, 118

Nuclease, 71

Nucleoproteid, character of, 3

cleavage products of, 71

Obesity, relation to food consumption, 270

Old age, metabolism in, 296

Osborne and Clapp, on chemistry of proteids of wheat kernel, 258

Osmosis, as factor in absorption, 41

Overeating, evil effects of, 270

Overfeeding, in laying on of fat, 98, 99

Oxidase, xanthin, 73

Oxidases, 64

Oxidation, in metabolism, 60

nature of, in the body, 60

older views regarding, 52

relation to enzymes, 75

site of, in the body, 62

value of respiratory quotient in determination of substances

undergoing, 125

views of Lavoisier on, 56

views of Liebig on, 57, 120

Oxidative cleavage, 61

Oxygen, in katabolism, 62

relation to decompositions in the body, 61

relation to proteid decomposition, 59

Oxygen consumption, in climbing, 116

in relation to work, 123

in standing at rest, 116

in walking, 116

Pancreatic digestion, of proteids, 34

products of, 34, 67

products of, of starch, 37

Pancreatic juice, composition of, 32

condition of trypsin in, 33

enzymes in, 32

secretion of, 31, 32

sodium carbonate in, 32

Paths of absorption, 44

Pawlow, on adaptation of saliva, 18

Pepsin, in gastric juice, 25, 26

Peptones, 67

absorption of, 41

cleavage by erepsin, 34

effects when injected into blood, 41

formed in gastric digestion, 26

Pflüger, E., theory of proteid metabolism, 138

views on muscle work, 123

Phenol, 37

Phloridzin diabetes, 130

Phosphorus, excretion of, in relation to work, 123

Photograph, of athlete, 190

of Fritz, 199

Photographs, of dogs, 248

of soldiers, 193

Physical endurance, _see_ Endurance

Physiological economy in nutrition, 264

Plastic foodstuffs, 58

Poisons, relation of body resistance to, on low proteid diet, 226

Polypeptid, 35

Portal vein, absorption of food products by, 45

Processes of metabolism, 51

Products, of cleavage of wheat kernel proteids, 259

of gastric digestion, 26

of pancreatic digestion, 37, 67

of proteid cleavage, 70

of putrefaction in intestine, 38

of salivary digestion, 21

Products of digestion, absorption of, 44

Professional men, fuel value of food on low proteid diet, 178, 180, 185

nitrogen equilibrium of, on low proteid diet, 176, 177, 181

true proteid requirement of, 174

Progeny, influence of meat diet on, in rats, 240

Prosperity, relation to food consumption, 160

Proteid, absorption of, in dogs on low proteid diet, 233, 262

absorption of cleavage products, 47

amounts of food required to supply needs of body for, 272

as food, 3

as fuel, 6

as glycogen former, 130

as source of energy, 122, 123, 124, 129

as source of energy, in fasting, 81

availability of, 12

body-weight on diet low in, 170–175, 181, 185, 190, 199, 245, 249,

250, 251

carbon moiety of, 129

chemical basis of protoplasm, 51

circulating, 134

cleavage products of, 70

composition of, 3, 69

consumption by fruitarians, 217

consumption by Japanese, 219, 221

decomposition by oxygen, 59

decomposition in work, 58

excessive consumption of, relation to disease, 269

effect of diet exclusively of, on rats, 239

effect on dogs of diet low in, 233, 234, 237, 245–255

fat absorption in dogs on diet low in, 261

food, real need of body for, 272

formation of carbohydrate from, 129

fuel value of, 15

fuel value of, metabolized during fasting, 86

influence of chemical character of, on nutrition, 256

diet exclusively of, upon progeny of rats, 240

diet low in, on high proteid animals, 231, 233, 243

on excretion of nitrogen, 59, 87, 90

on metabolism, 83

on metabolism of, 88

in foodstuffs, 7

katabolism, 75

luxus consumption of, 59

metabolized during fasting, 86

minimum requirement, 59

morphotic, 134

need of body for, 268

nitrogen equilibrium on diet low in, 176, 177, 181, 200, 201, 245,

249, 250, 251, 252, 255

overfeeding with, 98

reconstruction of, during absorption, 42

relation of endurance to diet low in, 210, 212

relation of fatigue to diet low in, 208

respiratory quotient of, 107

resistance of body to poisons on diet low in, 226

safety in relation to diet low in, 231

significance of complete cleavage of, 35

storing of, 92, 98, 99, 100

strength tests on diet low in, 203, 206

synthesis, 48, 49, 68

utilization of fat in dogs on diet low in, 261

utilization of nitrogen in dogs on diet low in, 262

work done at expense of, 58

Proteid diet, experiments of Neumann on low, 286

body-weight of dogs on low, 245, 249, 250, 251

body-weight of men on low, 170–175, 181, 185, 190, 199

in relation to nitrogen excretion during hard work, 123, 124

vegetable foods in relation to, 291

Proteid metabolism, influence of carbohydrate on, 92, 94, 95, 96, 97

influence of fat on, 92, 93, 96, 97

influence of proteid on, 59, 87, 90

Folin’s theory of, 144

Pflüger’s theory of, 138

significance of, 131

Voit’s theory of, 134

Proteid requirement, fuel value of food in experiments on, athletes, 188

fuel value of food in experiments on, professional men, 178, 180, 185

fuel value of food in experiments on, soldiers, 198

in dogs, experiments of Jägerroos, 236

in dogs, experiments of Munk, 232

in dogs, experiments of Rosenheim, 234

in dogs, experiments of author, 243

in man, 169, 170, 171, 172, 174–202

nitrogen excretion in experiments on, athletes, 186, 187, 188

nitrogen excretion in experiments on, in dogs, 245, 249, 250, 251,

252, 255

nitrogen excretion in experiments on, professional men, 177, 180, 185

nitrogen excretion in experiments on, soldiers, 197, 200, 201

relation to body-weight, 184, 188, 198, 227

sample diets in experiments on, 178, 182, 189, 195

Proteids, as tissue formers, 58

of wheat kernel, cleavage products of, 259

Proteoses, 26, 67, 69

absorption of, 41

cleavage by erepsin, 34

effects when injected into blood, 41

primary, 67, 69

secondary, 67, 69

Protoplasm, 51

Protoproteose, 67, 69

Ptyalin, 20

Purin bases, 71, 72

relation to uric acid, 73

Putrefaction, in intestine, 37

products of, 38

Rats, effects of exclusive proteid diet on, 239

effects of rice on, 240

influence of meat diet on progeny of, 240

Renal activity, and diet, 297

and inorganic salts, 298, 299, 300

Rennin, in gastric juice, 26

Resistance of body to poisons, relation to low proteid diet, 226

Respiration calorimeter, 102

Respiratory foods, 58

Respiratory quotient, 107

influence of foods on, 107, 126

influence of metabolic change on, 108

of foodstuffs, 107

relation to work, 125

value of, in determination of substances oxidized, 125

Rest, carbon dioxide output during, 111

influence of, on oxygen consumption, 126

influence of, on respiratory quotient, 126

Rice, influence of, on growth in rats, 240

Rosenheim, Theodor, on proteid requirement in the dog, 234

Safety of low proteid standards, 231

Saliva, adaptation of, 18, 19

function of, 20

psychical secretion of, 18

secretion of, 17, 18

Salivary digestion, in stomach, 23

products of, 21

Salts, _see_ Inorganic salts

Saponification of fats, 36

Sarcosin, 74

Schnyder, 115

Scientific research and typhoid fever, 267

Seasons of the year, relation to diet, 296

Secretin, 32

Secretion, of gastric juice, 24

of pancreatic juice, 31, 32

of saliva, 17, 18

Sivén, on proteid requirement, 89

Skatol, 38

Sleep, heat production during, 104, 105

Soaps, 36

Sodium carbonate, in pancreatic juice, 32

Soldiers, fuel value of food in experiments on proteid requirement

of, 198

nitrogen equilibrium in experiments on proteid requirement

of, 200, 201

photographs of, 193

proteid requirement of, 192

sample diet in experiments on proteid requirement of, 195

strength tests in experiments on proteid requirement of, 203

Specificity of body fat, 44

Standard diets, 155

Standing at rest, oxygen consumption in, 116

Starch digestion, products of, 21, 37

Steapsin, 36

Stomach, absorption from the, 31

as a reservoir, 31

digestion in the, 25–31

fat digestion in the, 36

muscular movements of the, 27–30

salivary digestion in the, 23

time foods remain in the, 29, 30

Storing of proteid, 92, 98, 99, 100

Strength tests, on low proteid diet, athletes, 206

on low proteid diet, soldiers, 203

Sugar, in blood, 45

in blood, relation to glycogen, 46

Sugars, behavior when introduced into blood, 39

selective action in absorption of, 47

Sulphur, excretion of, relation to work, 123

Synthesis, of fat, 43

of proteid, 48, 49, 68

Temperance in diet, 166, 168, 270

Tissue formers, 58

Tissue metabolism, _see_ Endogenous metabolism

Trypsin, 32

condition in pancreatic juice, 33

Tryptophan, 67

Typhoid fever and scientific research, 267

Tyrosin, 34, 67, 70, 259

Underfeeding, dangers of, 214

Urea, 74

excretion of, influence of diet on, 144

relation of, to creatin and creatinin, 74

Uric acid, 73

excretion of, as influenced by diet, 144

relation of, to xanthin bases, 73

Urine, relation of diet to nitrogen distribution in the, 144

Utilization, of dextrose, 40

of disaccharides, 40

of fat in dogs on low proteid diet, 261

of nitrogen in dogs on low proteid diet, 262

Variety in diet, 229, 242

Vegetable diet, influence upon dogs, 254, 256

Vegetable foods, relation to low proteid dietary, 291

Vegetables, cellulose in, influence on digestion, 263

Voit, Carl, on minimum proteid requirement, 171

theory of proteid metabolism, 59, 134

Walking, oxygen consumption in, 116

Water in foodstuffs, 7

Watson and Hunter, influence of diet on growth in rats, 239

Wheat kernel proteids, cleavage products of, 259

Weight, _see_ Body-weight

Wislicenus, _see_ Fick and Wislicenus

Work, carbon dioxide excretion in relation to, 123

carbon dioxide excretion during, 111, 112

due to proteid decomposition, 58

effect of, on energy exchange, 109, 110, 113, 115

experiments on man, 110, 111, 112, 113, 114, 115, 116

heat production in, 110

influence of, on oxygen consumption, 126

influence of, on respiratory quotient, 126

nitrogen excretion during excessive, 127

nitrogen excretion during fasting in, 125

proteid decomposition in, 58

relation of diet to, 126

to energy exchange, 119

fats and carbohydrates to, 58

nitrogen excretion on proteid diet to hard, 123, 124

nitrogen excretion to proteid diet to hard, 122, 123, 124

relation of oxygen consumption to, 123

phosphorus excretion to, 123

sulphur excretion to, 123

respiratory quotient in relation to, 125

source of energy during fasting in, 125

views of Argutinsky on muscle, 123

views of Pflüger on muscle, 123

views of Voit on muscle, 59, 134

Xanthin, 72

Xanthin oxidase, 73