Vegetables of themselves are low in caloric value, their importance being due to the cellulose, salts, and vitamines they contain. But they are usually prepared with so much butter or cream that as served they have a high caloric value in fat. Lean meat is practically pure protein, and the tendency of the meat eater is to get an excess of this element. The vegetarian often goes to the other extreme, his diet showing a deficiency in protein, with an excess of fats and carbohydrates. That the protein balance be kept normal is an important matter, for a person may at one and the same time be suffering from the results of a deficient diet and also from the effects of overeating. The protein needed daily is from ten to thirteen per cent of the total ration. If the total daily ration is but one thousand five hundred calories, the protein should still be two hundred calories, and therefore thirteen per cent of the total. Thus if a person is living on foods containing less than ten per cent, there is danger of not getting enough of this important element. Much of the food eaten is less than ten per cent protein, because of the addition to it of fat and sugar in large amounts.
So-called meat substitutes should be high in the percentage of protein, in order to make up for the butter, sugar, oils, olives, desserts, fruits, and other very low protein foods that enter so largely into one's dietary. The question has been asked, Why object to the addition of fat to a meat substance, since it does not actually reduce the quantity of protein, though it does relatively? In reply, it may be said that the relative reduction makes necessary an excess of the nonnitrogenous foods, to get enough protein; and even though one's capacity should receive it comfortably, still the objection to the excess aliment remains.
A study of food composition and values will enable the housewife so to plan her meals that the various elements may be served to her family in the proper proportions. A knowledge of calories, and an intelligent application of the principles involved in these questions of nutrition, will enable any housewife to reduce the cost of feeding her family from twenty-five to fifty per cent, which would be worth while from an economical standpoint, not to mention the advantage to be realized healthwise.
Vitamines
Says Lusk, "It has thus far been shown that nutrition means fuel for the machinery, new parts with which to repair the machine, and minute quantities of vitamines, which produce a harmonious interaction between the materials in the food and their host."
In the words of another investigator, "The study of dietetics from the standpoint of the vitamines has only just begun." Sufficient has been learned and demonstrated about them, however, to show that they play a most important part in nutrition and in vital tissue processes. Since they are so little understood, a complete definition is not yet possible. The pure vitamine, it seems, cannot be isolated, so their exact chemical nature is not known. The chemical process necessary to free it is no sooner begun than the vitamine is apparently decomposed, and all trace of it is lost. One is reminded of the efforts of some early investigators to submit living protoplasm to a chemical analysis, they hoping thereby to reveal the mysteries of physical life itself; but at the first intrusion, this subtle something flees, taking its secrets with it, and leaving us only the empty shell of dead protein matter. While the activities and manifestations of life are seen on every hand in animal and plant, we are but little the wiser as to what life really is.
Vitamines seem to stand closely related to the living process in the tissue cells. Some investigators have thought them to be the mother substances of the various bodily ferments and internal secretions, any disturbance of which produces serious constitutional troubles. Therefore the continuous use of a diet lacking in any of these mother substances would of necessity lead to a deficiency of these absolutely essential vital secretions and ferments.
Vitamines and Disease