The figures in the above table were obtained by determining the amount of nitrogen in the dried excrement from the animals, i. e. the amount that passed through the intestine unchanged;[74] and knowing the content of nitrogen in the daily food, the percentage of unabsorbed nitrogen was then easily calculated, after which by simple subtraction the percentage of utilized nitrogen was found. At first glance, it would appear that as the experiments proceeded utilization of nitrogen was less complete. In a sense, this was true, but it was not connected with any impairment of the digestive or absorptive powers of the intestine. It must be remembered that in the earlier periods a larger proportion of the ingested nitrogen was in the form of readily digestible meat, but as the latter was reduced in amount larger proportions of vegetable food were introduced in order to maintain the desired fuel value, and consequently the percentage of non-absorbable nitrogen was increased. The well-known difference in the availability of animal and vegetable proteid has already been referred to in other connections; a difference due not so much to any inherent quality in the digestibility of the two forms of proteid as to the presence of cellulose and other material in the vegetable food which retards in some measure the action of the digestive juices. To this cause must be ascribed the slight falling off in the utilization of nitrogen noticeable in most of the experiments. If, however, the figures are compared with those usually obtained on a diet largely vegetable in nature, it will be seen that the utilization of nitrogen by these dogs was in no sense abnormal.
These experiments on the influence of a low proteid diet on dogs, as a type of high proteid consumers, taken in their entirety, afford convincing proof that such animals can live and thrive on amounts of proteid and non-nitrogenous food far below the standards set by Munk and Rosenheim. The deleterious results reported by these investigators were not due to the effects of low proteid or to diminished consumption of non-nitrogenous foods, but are to be ascribed mainly to non-hygienic conditions, or to a lack of care and physiological good sense in the prescription of a narrow dietary not suited to the habits and needs of this class of animals. Further, it is obvious that the more or less broad deductions so frequently drawn from the experiments of Munk and Rosenheim, especially in their application to mankind, are entirely unwarranted and without foundation in fact. Our experiments offer satisfying proof that not only can dogs live on quantities of proteid food per day smaller than these investigators deemed necessary, and with a fuel value far below the standard adopted by them; but, in addition, that these animals are quite able on such a diet to gain in body-weight and to lay by nitrogen, thereby indicating that even smaller quantities of food might suffice to meet their true physiological requirements.
The results of these experiments with dogs, which we have recorded in such detail, are in perfect harmony with the conclusions arrived at by our experiments and observations with man, and serve to strengthen the opinion, so many times expressed, that the dietary habits of mankind and the dietary standards based thereon are not always in accord with the true physiological requirements of the body. If these views are correct, and the facts presented seemingly indicate that they are, it is time for enlightened people to give heed to such suggestions, that their lives may be ordered more nearly in accord with the best interests of the body. Physiological economy in nutrition is not a myth, but a reality full of promise for the welfare of the individual and of the community in general. Ignorance on dietary matters should give place to an intelligent comprehension of the body’s needs, and an adequate understanding of how best to meet the legitimate demands of the system for nourishment under given conditions of life. It is said that more than half the earnings of the working people of this country is spent for food. Here, we have suggested another form of economy as worthy of consideration; less important perhaps than that which relates to health and strength, but still calling for thoughtful attention. We cannot afford to be ignorant of these things; we must have definite knowledge of the actual facts, and these can only be obtained by careful research and investigation.
As a prominent writer on nutrition has well said, “The health and strength of all are intimately dependent upon their diet. Yet most people understand very little about what their food contains, how it nourishes them, whether they are economical or wasteful in buying and preparing it for use, and whether or not the food they eat is rightly fitted to the demands of their bodies. The result of this ignorance is great waste in the purchase and use of food, loss of money, and injury to health” (Atwater). We all recognize the general force and truth of this statement, but there is a surprising lack of appreciation of the full significance of what is involved thereby. If it is true that the demands of the body for proteid food—which of all foods is the most expensive—are fully met by an amount equal to one-half that ordinarily consumed, and that health and strength are more satisfactorily maintained thereby, it is easy to see how the acquisition of dietary habits leading to consumption of food in harmony with physiological needs will result in a fruitful twofold economy; viz., economy in expenditure, and of still greater moment, economy in the activities of the body by which food and its waste products are cared for.
CHAPTER VIII
PRACTICAL APPLICATIONS WITH SOME ADDITIONAL DATA
Topics: Proper application of the results of scientific research helpful to mankind. Dietary habits should be brought into conformity with the true needs of the body. The peculiar position of proteid foods emphasized. The evil effects of overeating. What the new dietary standards really involve. The actual amounts of foodstuffs required. Relation of nutritive value to cost of foods. The advantages of simplicity in diet. A sample dietary for a man of 70 kilograms body-weight. A new method of indicating food values. Moderation in the daily dietary leads toward vegetable foods. The experiments of Dr. Neumann. The value of fruits as food. The merits of animal and vegetable proteids considered in relation to the bacterial processes in the intestine. A notable case of simplicity in diet. Intelligent modification of diet to the temporary needs of the body. Diet in summer and winter contrasted. Value of greater protection to the kidneys. Conclusion.
Knowledge has value in proportion to the benefit it confers, directly or indirectly, on the human race. Every new scientific fact or principle brought to light promises help in the understanding of Nature’s laws, and when rightly interpreted and properly applied is sure to aid in the advancement and prosperity of the individual and of the community. Proper methods of living, economical adjustment of the intake to the varying needs of the body, avoidance of excessive waste of foodstuffs and of energy, are all desirable precepts, which rational people presumably are inclined to follow so far as their knowledge and understanding of the subject will permit. Here, as elsewhere, false teaching may be exceedingly mischievous and lead to costly errors; while blind reliance upon customs, instinct, and superstitions is hardly in keeping with twentieth-century progress.
Modern scientific methods should give us help in dietetics, as in other branches of hygiene and practical medicine. A few short years ago, diphtheria was a scourge which brought misery to many a home, for there was at hand no adequate means of combating the disease; but scientific research has given us new light, and placed at our command a weapon of inestimable value. Do we hesitate to use it when the occasion arises, because it happens to be out of keeping with old-time customs and traditions? No, we recognize the possibility of help, and as the need is urgent we turn to it quickly, with hope and thankfulness that scientific progress has opened up a pathway of escape from a threatened calamity.
Not many years ago we drank freely of such water as was at hand, without realization of danger from bacteria or disease germs, looking on epidemics of typhoid fever perhaps as a visitation of Divine Providence, in punishment of our many sins and to be borne meekly and with resignation. But all this has changed through the researches of bacteriologists and chemists; scientific facts of the utmost importance have been clearly established; a classification of water-borne diseases has been adopted, and we realize fully that diseases of this order can be kept from our doors by proper precautions applied to our water supply. To-day, epidemics of typhoid fever are traceable solely to the ignorance or carelessness of the individual or of the commonwealth, and the exemption which we of the present generation have from this class of diseases is directly due to the application of precautionary measures based on the information furnished by scientific investigation. It is proper for us to use caution in the acceptance of new ideas, but not that form of caution which refuses change on the ground that what has been is sufficiently good for the present and the future. The point of view is ever changing with advance of knowledge, and it is not profitable to exclude opportunities for improvement in personal hygiene and general good health, any more than in other matters that affect the prosperity of the individual or the community.