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body under normal conditions of life. He considers that a person of 70-75 kilos weight requires 118 grams of proteid (of which 105 grams must be absorbable), 56 grams of fat, and 500 grams of carbohydrate. This standThis stand ard of Voit represents, therefore, a calorie value of 3055.6 or 43.65 calories per kilo of body weight.

The standards of Ranke, Atwater, Schmidt, Gautier, and others are approximately the same, although they differ somewhat in the relations of the different constituents. Von Noorden states that 1.3-1.5 grams of proteid per body-kilo are necessary to maintain the body in nitrogenous equilibrium, while it is immaterial whether the requisite calorie value (35-50 calories per kilo depending on the amount of work done) is brought up by fat or carbohydrate.

Recently Chittenden, in an elaborate study of the proteid requirements and metabolism of different classes (teachers, professional men, soldiers, and athletes), has shown that nitrogenous equilibrium may be satisfactorily maintained with about of the proteid standard of Voit. This work is of exceeding importance as it proves, beyond a doubt, that the proteid need, as indicated by the maintenance of nitrogenous equilibrium, is far below our generally followed standard of Voit. As Chittenden's experimental subjects were in excellent condition, both physically and mentally after a period of several months on such low proteid diet, it is very apropos to ask, "Is there any real scientific ground for the assumption that the average individual, doing an average amount of work, requires any such quantity of proteid or of total nutrients as the ordinary dietetic standards call for? "While it is true that this lowered standard of Chittenden may maintain the various individuals studied in nitrogenous equilibrium, it does not do so without answering the total caloric need of the individual, as evidenced by the fact that all of the subjects showed a calorie consumption of 30-40 calories per body-kilo: Chittenden says, "It is self-evident that the smallest amount of food, that will serve to keep the body in a state of high efficiency, is physiologically the most economical, and hence the best adapted for the needs of the organism. Any excess over and above what is really needed is not only uneconomical but may be directly injurious." Although it is doubtless true that the unnecessary overloading of the system with excessive products of proteid metabolism, may, in time, weaken the digestive, absorptive, assimilative, and excretory functions, yet we are not warranted, it seems to me, in assuming that the life and happiness of a normal being are,

necessarily, imperilled by a strict adherence to the Voit standard. As Magnus-Levy puts it, "Is it actually the case that life is constantly endangered, hovering as it is between the Scylla of toxins and the Charybdis of metabolic end-products?"

The question might be asked at this juncture, why do we consider the proteid content of a dietary as so much more important than the fat or carbohydrate values? If these latter constituents are utilized at all, they are oxidized to simple products, which are easily excreted and, hence cause no undue strain on the assimilative and excretory organs. Of course before being oxidized, a portion of both of these is stored up in a passive form subject to further orders from the system in general. I have, naturally, no reference, here, to the effect of an excessive fat or carbohydrate diet, which is a factor in the production of obesity or of diabetes.

With the proteids, however, a somewhat different course of events is observed. To be utilized by the system proteid must be built up into its constituent protoplasm. We are all familiar with the differentiation of proteid as organized or unorganized, stable or, labile, tissue or reserve, etc. It is unnecessary for me to do more than call attention to the conception of "reserve proteid" as being entirely analagous to reserve fat or carbohydrate. The proteids, on oxidation, are spilt up into various nitrogenous products, some of which may exert, if present in sufficient quantity, or if acting over long periods of time, untoward effects preceding and during their excretion. These metabolic end-products, or toxins as they have been styled, may cause some specific or local disturbance, which calls for their speedy removal. In the elimination of such products through the kidneys, definite lesions or at least functional insufficiency may arise. Moreover, the other organs of the body, which have to do with the further elaboration of these products, may suffer functional impairment in their attempt to keep pace with the excessive supply of elaborative material. Our knowledge regarding the formation and excretion of these nitrogenous end-products is too meager to permit us to say whether increased formation is accompanied by increased excretion of each product or whether, on a diet rich in proteids, these substances are retained to a greater extent than on a diet such as is advocated by Chittenden. On the solution of this point depends, it seems to me, the decision whether the Voit standard is a dangerous one. Naturally the excretion of an increased amount of these end-products might influence the secretory organs, but it remains to be proven whether the kidney, in health, is

or is not capable of excreting the products of metabolism of the proteid standard of Voit, without suffering undue strain.

Folin, in his careful work on proteid utilization, through which he was lead to formulate his "Theory of Proteid Metabolism, comes to the conclusion that our proteid dietary is much too high. His figures agree fairly well with those of Chittenden and are based on determinations of the exogenous and endogenous nitrogen. His work shows us how futile it is to draw conclusions, regarding the nitrogenous metabolism, from the amount of urea excreted. Of much greater importance is the nitrogen partition and, particularly, the amount of creatinin excreted in twenty-four hours, inasmuch as this nitrogenous constituent is the one nitrogen factor uninfluenced by a variation in the meat-free proteid diet.

It would seem, therefore, that we must accept the possibility that our proteid intake may be diminished to one-third to one-half of the Voit standard without causing any disturbance of the nitrogenous equilibrium or of the general health and physical activity. However the writer is inclined to believe, without having definite experimental grounds for his belief, that a diet, which keeps strictly within the prescribed standard of Voit, will work no lasting ill effect, unless the system be undermined by disease, which is not traceable to errors of diet, and in which no sensible physician would order a dietary high in proteid until the period of convalescence had been definitely established. It is most certainly true, that a moderate diminution of proteid is less harmful, providing the total diet be sufficient, than is an abundant proteid diet with a calorie deficit (von Noorden).

Accepting, then, that the average diet of a normal individual should contain from 30-50 calories per body-kilo and that the proteid. content of the dietary should run between three-fourths and one and one-half grams of proteid per kilo, we come to the discussion of the subject of our paper.

OVER-FEEDING.

By the term over-feeding or forced-feeding we mean the giving of an amount of food, which furnishes the body more energy than it needs, utterly regardless of whether the addition be in the form of proteid, carbohydrate, or fat (von Noorden).

The errors in diet, which most of us, unfortunately, commit, are productive on the one hand, of various disorders as a result of the overtaxing of the digestive, absorptive, assimilative, or excretory organs with excessive products of metabolic activity, and, on

the other, of a series of peculiar derange. ments, pointing to a condition of under untrition. I need only refer to the obese, diabetic, and gouty subject on the one side, and the neurasthenic, neuralgic, and chlorotic patient on the other. I shall, therefore, in this paper, treat of the subject of over-feeding, only as a therapeutic measure and not as an etiological factor in disease.

It has been shown by Rubner, MagnusLevy and others, that addition of an excess of food, in the form of fat or carbohydrate, exerts, even when given in large amounts only a slight increase in the energy relations of the system. This, of course, applies to an immediate increase in the oxidative processes and not to the later effects of the reserve fat or carbohydrate. Only a part of such excess is burned up in the system, the chief part being stored in the various depositaries subject to the checking orders of the system. On addition of fat to the diet almost the total excess of energy is turned to the advantage of the body, not in the form of increased energy, but, rather, in the form of latent energy as a deposition of fat. Zuntz has proven, that of 100 grams of fat-increase in the diet, 97-8 grams were stored up. With the carbohydrates the relations are not quite so high. A loss of 10%, according to Zuntz, is observed in the total energy available from an increase of carbohydrate. Moreover, the conversion of the carbohydrates into fat is accompanied by some loss of heat.

An increase of proteid in the diet raises, on the contrary, the general tissue metabolism, as evidenced by the increased oxidation, far above the normal standards and far above that, which could be traced to the activity of the bowel. This primary increase in the oxidative processes, which is effected by a meal rich in proteids, lasts for eight to ten hours. This fact may be expressed more briefly in the statement that, every addition of proteid increases the proteid decomposition, the system soon adapting itself to a new equilibrium. Right here it may be well to point out that it is erroneous to refer every loss of nitrogen to an increased decomposition of body-proteid. There is no reason for supposing that tissue-proteid is decomposed in any different way than is food-proteid. Likewise we are not justified in assuming that the products of tissue-metabolism are, normally, or abnormally, any different from those of food-metabolism under the same conditions. The point of all this is, that the increased nitrogen excretion observed under certain conditions may be referable to the proteids of the food and not to those of the tissues.

PROTEID-SPARING.

We all know that every addition of proteid to a normal diet yields a nitrogen retention for a few days and that the nitrogenous equilibrium is under these conditions, pitched to a higher scale as long as this increase lasts. Under a normal diet the proteid of the food is completely decomposed, the output equaling the intake. If the diet contains a normal amount of proteid but is increased by the addition of N-free constituents, a certain amount of N. is retained in the body. This is the well known point of proteid sparing and seems to be an exception to the law, that the body under all circumstances seizes, in the first place, upon the easily available proteids. If, however, we make an application of Guldberg-Waage's Law of Mass-Action, we see that the mass of a substance may be so great as to overbalance the greater affinity of a substance present in less quantity.

It has been shown that a large excess of fat and carbohydrate is necessary to protect small amounts of proteid from being oxidized in the system. If we withdraw large amounts of carbohydrate from the diet, the proteid decomposition increases, while the withdrawal of fat does not cause such a marked disturb. ance in the proteid metabolism. I mean by this that the nitrogenous equilibrium is better maintained by excess of carbohydrates than by fats, or in other words, sugar is a better "sparer" of proteid than is fat. This This point is of great importance in the ment of the obese.

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The fact that the body endeavors to regulate its proteid decomposition according to the intake and, hence, to oxidize the largest possible percentage of the proteid of the food, suffers exceptions in youth, pregnancy, convalescence, etc., inasmuch as growth and development of tissue would be impossible without a definite change in the nitrogenous relations.

FLESH AND FAT.

It would seem, then, that we have two ordinary forms of over-feeding. The one leading to increased fat formation and deposition, and the other to increased deposition of proteid. It is not an uncommon thing to find in our literature flesh and fat used as synonymous terms, but it seems needless for me, in this place, to point out the distinction between them.

It is self-evident that we may increase the fatty condition of the body regardless of the proportions of the food in a course of forcedfeeding. Theoretically there is no limit to the extent of this fat deposition, but practically it is limited by failing intestinal activity and disease of the vital organs. Natur

ally, however, one seeks, in instituting such a course, only the certain optimum nutrition. The rest-cures of Weir Mitchell, which consist of forced feeding along with massage and light exercise, tend to produce fatter but not stronger and more fleshy patients. In other words, the forced feeding works here as in the case of the Strassburg goose and not as in the case of the athlete. Muscular exercise, along with forced-feeding, gives far better results than the rest methods. Zuntz reports a case in which systematic muscular exercise for many days and weeks, along with forced-feeding, caused loss of weight but a simultaneous deposition of proteid, the calorie-consumption being greater at the end of the research than at the beginning. This experiment is confirmed by the everyday experience of our athletes.

INCREASED CALORIE-CONSUMPTION.

The increased calorie-consumption, as a result of forced feeding, rests upon two different factors (von Noorden):

1. The increase of decomposing protoplasm

Although definite relations exist between consumption of energy and body-mass as well as amount of surface, the amount of active decomposing protoplasm is of great importance in regulating the consumption of energy. The body-mass (weight) is important in average nutritive conditions only in so far as we may assume that a certain unit of weight of protoplasm corresponds to a certain unit of body-mass. If fat is added by over-feeding the body accumulates a weight-increasing substance, which shares very little in the energy relations of the body. As a result of this loading with ballast the conversion of energy, calculated to unit of weight, sinks smaller energy equivalent per kilo of the under forced-feeding, as in instanced by the obese. No definite quantitative relations have been established between increase of protoplsm and increase in consumption of energy, but such relations must exist.

2. Increase of body-mass, independent of the increase of protoplasm It is evident that the heavier the body-mass the more energy is needed to move or raise it. Hence, we observe the increase of work upon the muscular system, heart, and respiratory ap paratus of the obese. As mentioned above an increase of fat cannot aid in the oxidative processes through the influence of the fat itself but only through the weight-increasing influence of this otherwise useless substance. We all admit the value of a certain amount of fat as a reserve to meet the demands forced on the body by over-work or by disease, but few of us would

be rash enough, I believe, to proclaim the advantages of the excess fat in the obese. It is well to remember that the excess of food is not so important for the maintenance of the high nutritive condition as is the vital property of the protoplasm. We are, thereWe are, therefore, forced to admit that the ordinary forced-feeding, which leads to a deposition of fat and hence does not increase the direct energy equivalents of the system, is not the best practice.

INCREASE OF NITROGEN.

Von Noorden, Fr. Müller, Svenson, and others have shown that the human organism is not, under all conditions, disposed to Ndeposition. However, when an increase of N does take place in the system it may do so in several forms:

1. As extractives.
2. As proteid.

(a) Organized proteid.

(b) Unorganized porteid, labile proteid, reserve proteid, etc.

If the increase of nitrogen in the system has taken place in the form of extractives, we may have either an increased formation or a diminished excretion of these substances. It is not my purpose to discuss the importance of these factors as etiological units in disease; that would draw me too far from my theme. However, I must mention the facts that we have, in disease, both a primary retention and a primary formation of increased amounts of these substances as evidences of diseased conditions in the body.

The fact of the non-utilization of the unorganized or of the reserve proteid under normal conditions, has been previously mentioned. There may be a retention of nitrogen, but this does not, necessarily, mean an increase in the organized proteid. An increase of flesh in adult animals means an increase of volume, a hypertrophy of the individual cells but not an increase in their number (Magnus-Levy). Thus we see the increased muscular development under forced-feeding along with muscular exercise.

Although we have learned from research several methods of increasing the proteid of the body, we have little information as to how far the forced-feeding may go and what happens to the deposited proteid if the subject returns to his normal diet. It has been generally found that the retained proteid is lost under such circumstances. This makes it clear why the forced training and feeding of athletes is apt to result disastrously unless the same procedures, perhaps in a lesser degree, are kept up after the periods of active training. Too common are the uncompensated hearts and the emphysematous lungs to

need mention. While such changes are largely due to the strain of the training, the diet must be held partly responsible, inasmuch as the increased size of the organs and the hypertrophy of the individual cells is a result of the increased nutrition as well as of the increased work. Drop both and the condition is evident.

The question arises as to whether the deposited posited nitrogen is new capital with the same biological properties as the old. We must consider, in this connection, that not all of the nitrogen intake is converted into tissue proteid to compensate for the nitrogen output. It is certainly the case that, in the consideration of nitrogenous equilibrium, we usually regard the nitrogen output as equaling the intake. We, unfortunately, do not know just how much of this nitrogen intake is built up into true tissue-proteid nor how much of the nitrogen output is derived from decomposing tissue-proteid. Before the unorganized proteid or the retained extractive nitrogen can be utilized it must be converted into tissue-proteid as this is the form capable of oxidation. There is no reason for supposing that tissue-proteid, under the influence of the constantly occurring autolytic changes, splits any differently than does food-proteid, and hence we must consider the possibility of a synthesis of tissue proteid both from the cleavage products of food-proteid and from those of the autolysis of the tissue-proteids themselves. If the latter assumption be correct we must ask the question, may the tissue-proteids be renewed by the autolysis, and later synthesis from its own autolytic products? Such a change might seem useless, but when we consider that the wear and tear of the system necessitates the constant breaking down of tissueproteid and its renewal by new synthetic products the possibility does not seem so far-fetched. Were the tissue-proteids not constantly renewed the subject of nitrogenous equilibrium would be much simplified, as the output would consist, largely, of the metabolized and excreted intake rather than of the autolytic and retrograde products of tissue metabolism.

Time will not permit me to enter upon a discussion of the various ways of synthesizing proteids and so I can do no more than refer to the importance of the study of the work of Fischer upon the polypeptids. This work bids fair to unravel much of the mystery surrounding the chemical and "vital" activities of the "Awesome proteids."

How is it possible to decide whether a retention of nitrogen in the system means a gain in tissue or of reserve proteid? I quote from von Noorden.

1. If a deposition of N means proteid deposition, sulphur must also be retained.

2. If S-containing proteid, but no mineral constituents are retained, then the blood and lymph tissues come into consideration as the place of retention. In this case, the deposition of proteid is in the reserve form. 3. If proteid and mineral constituents are retained, then the proteid is built up into the constituent protoplasm of the system. A relatively large phosphorus retention is, as is well known, intimately connected with an increase of nuclear substance.

INDICATIONS FOR FORCED-FEEDING.

Forced proteid feeding is indicated in growing children, in pregnant and nursing women, in persons accustomed to increased work, in those who are under nourished as a result of chronic conditions such as carcinoma, tuberculosis, stomach diseases, etc., and in those convalescing from acute febrile conditions. In this latter group of cases the results to be obtained are far better than those observed where the inanition is due to chronic diseases.

UNDER-FEEDING.

It has been well said that he, who does not know how to estimate in how far the changes, which he observes at the sick-bed, are dependent on simple inanition, can not rightly interpret the metabolic changes, which arise from the disease itself.

Under this caption I will, varying from the method adopted in the discussion of over-feeding, refer more to the effects of a long continued under-feeding upon the system than to any therapeutic application, in asmuch as we can conceive of no case in which the adoption of a course of under-feeding would be advisable other than in the obese and in those who are chronically overfed.

By under-feeding we mean the giving of a diet insufficient in calorie value to meet the needs of the organism. Naturally we may have an under-feeding with one constituent and a relative over-feeding with another, and yet the calorie value be insufficient.

It is self evident to us all, that a definite relationship between proteid, carbohydrate, and fat is consistent with the best nutritive condition of the system. Granting that a normal individual needs a definite number of calories to satisfy the demands of the system, we must endeavor to supply this need by a proper combination of constituent dietary principles. An exclusive and excessive meat diet with insufficient calorie value (and a sufficient calorie value would be with difficulty reached in this way) will just

as surely lead to under nutrition as will a general calorie reduction with relative decrease in all the constituents of the diet. A high addition of proteid, if unprotected by a sufficient amount of N free food, is unable to maintain the nitrogenous equilibrium, because the energy required for the preservation of the body functions must, in this case come from increased proteid change. Hence we should recognize as a law that, caloric undernourishment, with high proteid content, can not protect the system against loss of body proteid.

It is true that, at present, under nourishment or underfeeding is usually referred to as a lack of nitrogenous substances in the diet. Yet we must remember that the fats and carbohydrates, if reduced to a marked extent, will not only lead to a loss of proteid, but will necessitate an increase of nitrogenous substances in the diet in order that the requisite calorie value be maintained. In this way we might conceive of the paradoxical condition of a one-sided over-feeding combined with general under-feeding. Of course the metabolic results would here be very different from those of an over-feeding previously discussed, because, technically, we have no increase of calories and consequently no over-feeding.

General under-feeding leads to a loss of glycogen, fat, and both organized and unorganized proteid. Without sufficient calorie value of the food and, in general, without a definite relationship of the constituent parts of the dietary, the system can take little or no advantage of the diet, but, rather, uses up its own store of these constituents to furnish the energy required. We can readily see, therefore, why long continued under-feeding leads to gradual weakness and impairment of functional activity throughout the system. certain amount of fat deposit is, as stated above, a protection against greater N-loss on an insufficient diet. Thus, in the obese a calorie deficit does not always lead to N-loss, at any rate more seldom and in less degree than in the spare.

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The following general effects of a long continued under-feeding are to be recognized (von Noorden):

1. The proteid decomposition sinks up to a certain point, beyond which further decomposition is serious. The body, at this point, adapts itself to a fairly permanent equilibrium, as is shown by the fact that not so much body-proteid is lost in the later periods as in the beginning. Nitrogenous equilib rium can be maintained, as Voit, Rumpf, Siven, and others have shown, on a lower proteid addition than is customary, provided the calorie need is covered. I recall, in this connection, the maintenance of nitrogenous

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