Physiological economy in nutrition, with special reference to the minimal proteid requirement of the healthy man / an experimental study

by R. H. Chittenden

When we recall that these 18 grams, or more, of nitrogen in the urine reach the final stage of urea, etc., only by passing through a series of stages, each one of which means the using up of a certain amount of energy, to say nothing of the energy made use of in digestion, absorption, etc., we can easily picture to ourselves the amount of physiological labor which the daily handling by the body of such amounts of proteid food entails. Further, it needs very little imagination to see that a large amount of energy is used up in passing on these nitrogenous waste products from organ to organ, or from tissue to tissue, on the way to elimination, and we can fancy that liver and kidneys must at times rebel at the excessive labor they are called upon to perform.

Moreover, the thought suggests itself that possibly these waste products of proteid metabolism, the leucomaines so abundantly formed in the breaking down of proteid material, are not wholly free from objectionable features. If so, an excess of such products might be advantageously dispensed with. Indeed, we have what seems abundant evidence tending to show that many of the nitrogenous waste products elaborated in the body through the breaking down of proteid materials are possessed of more or less physiological action. Even that direct antecedent of urea, ammonium carbamate, which we have reason to believe is formed more or less generally throughout the tissues of the body, is not above suspicion. To be sure, Nature has provided a mechanism in the hepatic cells whereby it is quickly transformed into the harmless urea, but it is only necessary to join the portal vein to the hepatic vein, thereby throwing the liver out of the circuit, in order to see the effect of an excess of proteid food. Under such conditions, this is followed by the appearance of all the symptoms of poisoning with ammonium carbamate, i. e., convulsions ending in death.[45]

Further, we may refer to the observations of Mallet[46] with creatin and creatinin, two conspicuous nitrogenous bases present in muscle, which show unmistakably that these bodies tend to retard slightly the action of the heart. This seems to be their most decided physiological effect, although large doses likewise cause a slight frontal headache, with some general nervous agitation. Attention may also be called to the extremely important experiments of Minkowski,[47] in which he found that adenin—one of the purin bases formed in the breaking down of cell nuclei—has a most marked toxic action, both on man and on dogs. Adenin affects the circulatory apparatus very strikingly, increasing the heart’s action, etc.; it acts on the mucous membrane of the duodenum, causing an acute inflammation, thus leading to continuous vomiting, and in addition it has a local action on the kidneys, giving rise to a deposition in the kidney itself of spheroliths of uric acid, or urates, which leads to an acute nephritis with albuminuria, from which the animal speedily dies.

The alloxuric bases likewise cause fever when injected into the circulation or taken per os,[48] and according to the recent observations of Mandel[49] there is a very noticeable relationship between the amount of alloxuric bases eliminated through the urine and the temperature of the body in cases of aseptic fevers, indicating that these substances, with possibly other incomplete products of tissue metabolism, are important factors in the production of febrile temperatures.

Reference may also be made to our general knowledge regarding the relationship between uric acid and gouty affections, including rheumatism, to say nothing of the possible relationship between uric acid and many other diseases less clearly established. The broader question deserving attention just here, however, is that all of the so-called leucomaines which, as Gautier states, are being formed continuously in the animal tissues side by side with the formation of urea and carbonic acid, and at the expense of the nitrogenous elements or proteid matter, are more or less toxic in their properties, at least under certain conditions of the body. It is perfectly clear that there are a large number of leucomaines, or nitrogenous waste products, which are indissolubly connected with the metabolism of cell protoplasm, and the formation of these substances is augmented by a diet rich in proteid matter.

It is well understood that the excretions of all living organisms, both plant and animal, are more or less poisonous to the organisms which produce and excrete them. The substances so formed originate in the metabolic changes by which complex organic molecules are broken down into simpler compounds. As stated by Vaughan and Novy,[50] “we have good reason for believing that the proteid molecule has certain lines of cleavage along which it breaks when certain forces are applied, and that the resulting fragments have also lines of cleavage along which they break under certain influences, and so on until the end-products, urea, ammonia, water, and carbon-dioxide, are reached; also that some of these intermediate products are highly poisonous has been abundantly demonstrated.” It would therefore seem self-evident that the nitrogenous waste products of the body, i. e., the products of proteid katabolism, may be more or less dangerous to the welfare of the body, and consequently there would seem to be reason in the assumption that greater freedom from disease—especially from the so-called autogenous diseases—might be expected where greater care is exercised in the amount of proteid food consumed.

It is generally understood, or at least is frequently stated by medical writers, that certain febrile conditions are autogenous, and Brunton has made the assertion that the condition termed “biliousness,” and which is most prone to occur in persons who eat largely of proteid foods, is due to the formation of poisonous alkaloidal-like substances which might well be classified under the broad term of leucomaines. To repeat, there are a great many observations and some facts which warrant the view that the nitrogenous waste products of the body—the products of proteid katabolism—are more or less dangerous to the well-being of the organism, and hence there seems justification for the belief that there is greater safety for health and longevity in adopting dietetic habits that are more in accord with the real needs of the body.

The writer’s opinion upon this question has been greatly strengthened by the large numbers of letters he has received—during the course of this inquiry—from persons all over the world, many of whom in their search for health and strength have adopted more frugal methods of living, and who have found relief in an abstemiousness which, compared with ordinary dietetic standards, would seem quite inadequate to support life, yet they have recovered health and strength, and by the judicious practice of physiological economy in their diet have maintained health and vigor, with capability for work that has proved a perpetual surprise to themselves and their friends. The writer’s faith in these spontaneous statements made by persons wholly unknown to him has been augmented by his personal knowledge of people suffering with various troubles, who have found relief by the simple use of reason and judgment in the taking of food, with a view to lowering the rate of proteid metabolism. There is no question in the mind of the writer that excessive proteid decomposition within the body entails possible danger.

If it is true, on the other hand, that the healthy organism needs a daily intake of 118 grams of proteid food more or less, in order to maintain physiological equilibrium, to keep up physical and mental vigor, and to preserve the normal power of resistance to the incursions of disease, then we must consider that the good overbalances the evil, and that evil exists in order that good may be accomplished. We are certainly justified, however, in saying, on the basis of our daily observations made on a large number of individuals and extending over many months, that there is no apparent need for any such amount of proteid food as is ordinarily consumed by the average individual.