In the past, it has been customary to express the value of a diet largely in terms of heat units, or calories, since it was supposed that the value of foods depended largely, if not entirely, upon the amount of heat produced from the consumption of their so-called nutritive constituents protein, carbohydrate, fat, etc. Therefore, with the rise in prices of foods generally, as the result of the great war, the public was well advised to consider the caloric value of the foods purchased, in order that the greatest possible amount of energy might be obtained for the least expenditure of means.
The result was, there came a tendency to purchase food by the calorie rather than by the kind. This principle is all right so far as it goes ; but in the light of our newer knowledge on the subject of nutrition, it falls far short of the actual needs of the human machine, which is infinitely more complicated than an ordinary mechanical contrivance.
As a result of biological studies carried on during the past few years, much light has been thrown on this important subject. For instance, a diet was constructed in which protein was represented by the casein in milk, carbohydrate by starch, and fat by lard, all carefully purified by chemical treatment, so as to exclude anything but these three substances. This was fed to young rats in quantity more than sufficient for their daily output of energy. Such a diet is sufficient, both in quantity and in quality, for the nourishment of the animal; but it does not contain any of the vital constituents of fresh foods, the vitamines. In theory, this should form an ideal diet; but in practice, it was found that the animals soon ceased to grow, and also developed certain diseases, notably rickets and scurvy. When this stage had been reached, a small quantity of fresh uncooked food was added to the diet, whereupon growth was resumed and the animals became healthy again.
Further experiments brought to light three very important additional facts ; namely, that animals fed on chemically pure foods showed a markedly diminished power of resistance to infectious diseases ; and in the case of female rats, the offspring were poorly developed ; and the mothers were unable adequately to suckle their young. Dr. Harvey W. Wiley, expert in food and nutrition, says :
“Up to the era of the discovery of the cause of beriberi, the principles of correct diet were based upon the supply of a so-called balanced ration. . . . We were taught that this balanced ration consisted of certain amounts of protein, carbohydrate, fat, and minerals. Much to the astonishment of physiologists, it was discovered that when an animal was fed pure protein, pure carbohydrate, pure fat, and pure mineral, it failed to grow, gradually lost weight, and finally died.”
“Our whole system of diet, therefore, has to be reconstructed from the discoveries of the last fifteen or twenty years. These discoveries have particularly emphasized the food value of the external coatings and germs of cereals. This value rests not alone in their content of ordinary digestible foods, but exists particularly by reason of the water-soluble vitamine contained therein.
“Perhaps there is no point in medicine so confusing and conflicting as the dietaries prescribed by the attending physician in case of illness, and likewise for children and grown persons as a preventive of disease. The very foods that have been most de-natured, and therefore are least wholesome and assimilable, are constantly prescribed by physicians for the well as for those who are ill. The functions of leaf vegetables, for instance, so important in dietetics, and carrying as they do the chief fat-soluble vitamines, are those that the physician too often neglects.” Quoted in “Literary Digest,” June 7, 1919.
Thus we find that there are three vitamines ; and there are possibly more, as scientists believe there is a fourth which cures rickets in children ; and there may be others. Vitamines are not manufactured in the body; neither are they contained in soil, in combination with minerals ; but they are elaborated by the plant itself. A lack of these accessories in the daily food is a species of starvation, and ends disastrously unless the body can be supplied with those substances so abundantly provided in unprocessed and uncooked foods. The subject is one that presents fascinating fields for experimental study and research; and every advance step serves to bring us nearer to nature and to nature’s God, leading to the avoidance of needless suffering and disease, and to the betterment of mankind.