It is also well known that in order to preserve health and proper weight there must exist in the economy a certain balance or equilibrium between the amount of the ingesta and excreta, representing the various elements which enter into nutrition; thus we speak of a nitrogen equilibrium, a carbo-hydrate equilibrium, a phosphorus equilibrium, and iron equilibrium, etc., some of which are disturbed continually in ill health and in various diseases, including cancer, as has been shown in our last lecture.
Until quite recently the principles of diet (even if not often carried out in practice) have been established on lines laid down by Carl Voit, of Munich; this eminent physiologist, after studying the dietary habits of various classes of workers, claimed that the adult man of 150 pounds, doing moderate muscular work, requires daily 118 grams of protein or albuminous food, 56 grams of fat, and 500 grams of carbo-hydrate, with a total fuel value of 3000 large calories, in order to maintain the body in equilibrium. But the remarkable and scientific experiments of Chittenden have demonstrated beyond question that perfect bodily and nitrogenous equilibrium can be maintained with one-third of the amount of protein called for by the Voit standard, and with a total value in the diet of only about 1600 calories, or about one-half of that indicated as necessary by Voit. These experiments were based on a group of five men of varying ages, professors and instructors at Yale, thirteen volunteers from the Hospital Corps of the United States Army, and eight students in Yale, all thoroughly trained athletes, twenty-six in all.
It would be quite beyond the scope of this lecture to enter at all into the intricate questions connected with the metabolism of nitrogenous and other foods, but Chittenden has well put the reasons “why prominence is given to the establishment of nitrogenous equilibrium and why the proteid intake assumes a greater importance than the daily amount of fat and carbo-hydrate consumed. Fats and carbohydrates when oxidized in the body are ultimately burned to simple gaseous products, viz., carbonic acid and water. Hence these waste products are easily and quickly eliminated and cannot exercise much deleterious influence, even when formed in excess.... With protein foods, on the other hand, the story is quite different. These substances when oxidized yield a row of crystalline, nitrogenous products which ultimately pass out of the body through the kidneys. Prior to their excretion, however, these products—frequently spoken of as toxins—float through the body and may exercise more or less of a deleterious influence upon the system, or, being temporarily deposited, may exert some specific or local influence that calls for speedy removal. Hence the importance of restricting the production of these bodies to the minimal amount, owing to their possible physiological effect and the part they are liable to play in the causation of many diseased conditions.”
When we consider the small share which nitrogen plays in the composition of the human frame, as shown in the table presented, only three per cent., it is easy to see how an excess of nitrogenous food must necessarily either pass off unassimilated or undergo imperfect metabolism, and so derange the general metabolism; and this is found to be the case in many conditions of disease, and, as has been shown, in cancer. Chalmers Watson and others have shown in a most remarkable manner, by animal experiments, that an excessive meat diet alters very materially the microscopic structure of very many organs and portions of the body.
Beneke, who is often quoted, was one of the first to seriously consider the actual diet beneficial in cancer, his observations dating back to 1875 upon material in the service of Esmarck and Oldehop, who treated patients according to his plan. While the diet he gives is not wholly vegetarian, he limits the nitrogenous intake very greatly, and reported some very favorable results, with the complete disappearance of some malignant new formations.
Referring now to the data presented in the second lecture, in regard to the frequency and geographical distribution of cancer, we can understand better, on scientific grounds some of the reasons why cancer is so steadily increasing in civilized communities, and why in some sections of the earth it is less common, while certain aborigines have seemed to be almost immune.
We found that in England the per capita consumption of meat was 130 pounds per year, and that it had doubled during the past fifty years, while during the same period cancer had increased four fold; but in Ireland, where the meat consumption was estimated in 1895 at only 40 pounds per capita, or less than one-third that in England, the cancer death rate is very much lower, not much over one-half. We found that in Italy, where the per capita consumption of meat was the smallest of any European country the cancer death rate was almost the lowest. Also that in certain other countries, where vegetarianism was the rule, cancer was very infrequent, while among certain aborigines the disease was practically unknown; but we found also that in both the latter classes of individuals cancer has slowly increased, in proportion as the inhabitants of different sections had come under the influence of modern civilization, and adopted the dietary and other habits of foreigners.
In the United States cancer has certainly increased very greatly during the last fifty years, and statistics were presented showing that in seven of the largest cities, during the past five years, the number of cancer deaths had augmented between seven and eight per cent. It is known that the consumption of meat here has increased steadily, until in a communication from the Bureau of Agriculture in Washington we learn that it had recently reached the enormous amount of 172 pounds per capita yearly, much more than in England.
Cancer has been repeatedly spoken of as a disease of civilization, and there are many other elements besides meat to be considered in connection with its etiology.
Coffee and tea are so widely and almost universally used in civilized countries, and their apparently pleasant effect is so great that few realize the harm that may result therefrom; although from time to time their injurious effects, especially along the line of digestive and nervous troubles, are dwelt on by medical writers. Of late years, however, more attention has been paid to their influence on metabolism and also to the relation of their consumption to the increase of cancer. From a report to the House of Commons in England, Holland is shown to be the largest per capita consumer of coffee of any country in Europe, and the cancer death rate there in 1905 was among the highest, while Hungary was the smallest consumer of coffee, and the cancer mortality in 1903 was only 39 per 100,000, or a little over one-third that in Holland. It may be interesting to know that Thompson states that “the people of the United States consume one-third of the total coffee produced, or more than Germany, Austria, Hungary, France and the United Kingdom combined. On the other hand England and her colonies consume one-half of the world’s output of tea, and the United States but one-fifth of it.”