Experiments on animals prove that fine flour alone, which is chiefly carbon, will not sustain life more than a month, while unbolted flour furnishes all that is needed for every part of the body. There are cases where persons can not use such coarse bread, on account of its irritating action on inflamed coats of the stomach. For such, a kind of wheaten grit is provided, containing all the kernel of the wheat, except the outside woody fibre.
When the body requires a given kind of diet, specially demanded by brain, lungs, or muscles, the appetite will crave food for it until the necessary amount of this article is secured. If, then, the food in which the needed aliment abounds is not supplied, other food will be taken in larger quantities than needed until that amount is gained. For all kinds of food have supplies for every want of the body, though in different proportions. Thus, for example, if the muscles are worked a great deal, food in which nitrogen abounds is required, and the appetite will continue until the requisite amount of nitrogen is secured. If, then, food is taken which has not the requisite quantity, the consequence is, that more is taken than the system can use, while the vital powers are needlessly taxed to throw off the excess.
These facts were ascertained by Liebig, a celebrated German chemist and physicist, who, assisted by his government, conducted experiments on a large scale in prisons, in armies, and in hospitals. Among other results, he states that those who use potatoes for their principal food eat them in very much larger quantities than their bodies would demand if they used also other food. The reason is, that the potato has a very large proportion of starch that supplies only fuel for the capillaries and very little nitrogen to feed the muscles. For this reason lean meat is needed with potatoes.
In comparing wheat and potatoes we find that in one hundred parts wheat there are fourteen parts nitrogen for muscle, and two parts phosphorus for brain and nerves. But in the potato there is only one part in one hundred for muscle, and nine tenths of one part of phosphorus for brain and nerves.
The articles containing most of the three articles needed generally in the body are as follows: for fat and heat-making—butter, lard, sugar, and molasses; for muscle-making—lean meat, cheese, peas, beans, and lean fishes; for brain and nerves—shell-fish, lean meats, peas, beans, and very active birds and fishes who live chiefly on food in which phosphorus abounds. In a meat diet, the fat supplies carbon for the capillaries and the lean furnishes nutriment for muscle, brain, and nerves. Green vegetables, fruits, and berries furnish the acid and water needed.
In grains used for food, the proportions of useful elements are varied; there is in some more of carbon and in others more of nitrogen and phosphorus. For example, in oats there is more of nitrogen for the muscles, and less carbon for the lungs, than can be found in wheat. In the corn of the North, where cold weather demands fuel for lungs and capillaries, there is much more carbon to supply it than is found in the Southern corn.
From these statements it may be seen that one of the chief mistakes in providing food for families has been in changing the proportions of the elements nature has fitted for our food. Thus, fine wheat is deprived by bolting of some of the most important of its nourishing elements, leaving carbon chiefly, which, after supplying fuel fur the capillaries, must, if in excess, be sent out of the body; thus needlessly taxing all the excreting organs. So milk, which contains all the elements needed by the body, has the cream taken out and used for butter, which again is chiefly carbon. Then, sugar and molasses, cakes and candies, are chiefly carbon, and supply but very little of other nourishing elements, while to make them safe much exercise in cold and pure air is necessary. And yet it is the children of the rich, housed in chambers and school-rooms most of their time, who are fed with these dangerous dainties, thus weakening their constitutions, and inducing fevers, colds, and many other diseases. The proper digestion of food depends on the wants of the body, and on its power of appropriating the aliment supplied. The best of food can not be properly digested when it is not needed. All that the system requires will be used, and the rest will be thrown out by the several excreting organs, which thus are frequently over-taxed, and vital forces are wasted. Even food of poor quality may digest well if the demands of the system are urgent. The way to increase digestive power is to increase the demand for food by pure air and exercise of the muscles, quickening the blood, and arousing the whole system to a more rapid and vigorous rate of life.
Rules for persons in full health, who enjoy pure air and exercise, are not suitable for those whose digestive powers are feeble, or who are diseased. On the other hand, many rules for invalids are not needed by the healthful, while rules for one class of invalids will not avail for other classes. Every weak stomach has its peculiar wants, and can not furnish guidance for others.
We are now ready to consider intelligently the following general principles in regard to the proper selection of food:
Vegetable and animal food are equally healthful if apportioned to the given circumstances.