Chapter VIII: Practical Applications with Some Additional Data (2)

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:

+---------+--------+-----+--------+---------+---------+---------+
| | | | Carbo- | |Calories | Proteid |
| Period. |Proteid.|Fat. |hydrate.|Calories.| per | per |
| | | | | |Kilogram.|Kilogram.|
+---------+--------+-----+--------+---------+---------+---------+
| | grams |grams| grams | | | grams |
|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

A

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

B

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

C

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

D

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

E

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

F

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

G

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

H

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

I

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

J

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

K

Katabolism, 50
nature of proteid, 75
oxygen in, 62
relation to intracellular enzymes, 75

Klemperer, on proteid requirement, 171

L

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

M

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

N

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

O

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

P

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

R

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

S

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

T

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

U

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

V

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

W

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

X

Xanthin, 72

Xanthin oxidase, 73