VI. GENERAL CONCLUSIONS.
When this investigation, the results of which have been detailed in the foregoing pages was first planned, it was intended to be simply a physiological study of the minimal proteid requirement of the healthy man, extended over sufficient time to render the results of scientific and practical value. There were no special theories involved, no special system of dietetics in view, but the object was simply to ascertain experimentally the minimum amount of proteid or albuminous food necessary for the maintenance of health and strength, under ordinary conditions of life. The impression in the mind of the writer was that there was no satisfactory scientific evidence to support the views held by most, if not all, physiologists regarding the needs of the body for food, especially nitrogenous or proteid food, and that the dietary standards universally adopted by scientific men were of very questionable accuracy, being founded mainly upon the customs and habits of mankind rather than upon any systematic study of what the actual necessities of the body are.
The results attained have certainly thrown a great deal of light upon this question of minimal proteid requirement, and the experimental study has been throughout a purely physiological one, but as the work has progressed the writer has been more and more impressed with the importance and significance of the results in their bearing upon the broader problem of general physiological economy in nutrition. There is no question, in view of our results, that people ordinarily consume much more food than there is any real physiological necessity for, and it is more than probable that this excess of food is in the long run detrimental to health, weakening rather than strengthening the body, and defeating the very objects aimed at.
Confining our conclusions to general statements, it may be said that our results, obtained with a great diversity of subjects,justify the conviction that the minimal proteid requirement of the healthy man under ordinary conditions of life is far below the generally accepted dietary standards, and far below the amounts called for by the acquired taste of the generality of mankind. Expressed in different language, the amount of proteid or albuminous food needed daily for the actual physiological wants of the body is not more than one-half that ordinarily consumed by the average man. Body-weight (when once adjusted to the new level), health, strength, mental and physical vigor, and endurance can be maintained with at least one-half of the proteid food ordinarily consumed; a kind of physiological economy which, if once entered upon intelligently, entails no hardship, but brings with it an actual betterment of the physical condition of the body. It holds out the promise of greater physical strength, increased endurance, greater freedom from fatigue, and a condition of well-being that is full of suggestion for the betterment of health.
Physiological economy in nutrition means temperance, and not prohibition. It means full freedom of choice in the selection of food. It is not cereal diet nor vegetarianism, but it is the judicious application of scientific truth to the art of living, in which man is called upon to apply to himself that same care and judgment in the protection of his bodily machinery that he applies to the mechanical products of his skill and creative power.
Food requirements must of necessity vary with changing conditions, but with due recognition of this fundamental principle, all the results so far obtained in this investigation, with a great variety of persons, point to the conclusion that the real demands of the body for proteid food do not exceed fifty per cent of the amount generally consumed. One-half of the 118 grams of proteid food called for daily by the ordinary dietary standards is quite sufficient to meet all the real physiological needs of the body, certainly under ordinary conditions of life; and with most individuals, especially persons not leading an active out-of-door life, even smaller amounts will suffice.Excess means waste, but of far greater importance is the unnecessary strain placed upon the body by this uncalled-for excess of food material, which must be gotten rid of at the expense of energy that might better be conserved for more useful purposes.
Further, thetotalconsumption of food by the average individual, non-nitrogenous as well as nitrogenous, is considerably greater than the real needs of the body demand, although here we must give closer heed to the varying requirements of the body incidental to varying degrees of activity. The man whose work is mainly mental has no real need for high fuel values in his daily ration. For such a man, a high potential energy in the daily intake of food is an incubus and not a gain. Body equilibrium can be maintained on far less than 3000 calories per day by the brain worker, and in the interest of health, strength, and vigor, as well as scientific truth, why teach the doctrine that a healthy man needs, on an average, foodstuffs to furnish 3000 calories or more per day, with 16 to 18 grams of nitrogen in the form of proteid? Moreover, as our experiments have clearly indicated, even the man who is called upon to perform considerable physical work has no apparent need for a fuel value in his food of 3000 calories per day. No doubt, the man who works at hard labor for ten or twelve hours a day will require a larger intake of fats and carbohydrates, sufficient to yield even more than 3000 calories, but this is not true of the moderate worker, nor of the average man whose work is in large measure mental rather than physical.
Finally, the writer may be permitted to express the hope that the outcome of this experimental work will serve to arouse scientific and intelligent interest in a subject which promises fruitful results for the individual, and for the community.