The animal and vegetable kingdoms supply the organic substances which constitute a large part of the material commonly known as food, and which sustain the body in life and strength.
In addition, various inorganic substances enter into the human structure, prominent among which are salt, lime and iron. Salt is so important to animal life that herds of wild animals have been known to travel many miles to the salt-licks, or springs, in search of it. Some persons, from habit, use it to excess in seasoning their food. Lime and iron are taken into the body through the food. Iron forms about one part in a thousand of human blood.
Classification of Foods.—For increasing weight and producing heat, the fatty portions of meat, butter, and lard, together with wheat, Indian corn, and sugar, are best adapted; for muscle-making, lean meat, peas, beans, oatmeal; for brain and nerves, shell-fish, lean meats, peas, and beans. Those who lead an active, bustling life, especially if they take an abundance of out-door exercise, will naturally crave strong food in unstinted supply. The busy brain-worker, who is housed all day, and scarcely rises from his chair, needs to be much more careful in his diet. Coarse bread, lean meats, and fruits should constitute his chief dependence, with very limited use of butter, oils, and sugar.
Proper digestion depends upon the power of appropriating the food supplied, and this, in turn, upon the needs of the system. The best of food cannot be properly digested when it is not needed. All that the system requires will be used, and the rest will be cast out by the organs of excretion, which are often overtaxed, and the vital forces wasted, in the effort. The liver especially is burdened in its effort to carry off the excess of carbonaceous matter from the blood, and biliousness is the result. On the approach of warm weather, when the air has less oxygen to consume the food, this is particularly true.
Quantity.—We should eat to live, not live to eat. More people suffer from over-eating than from eating too little. Many thin people are large eaters, and stout people are often small eaters. The young generally eat more than the old. Not only are their powers of digestion better, due in part to the great amount of exercise they take, but they need food for growth, as well as to repair the waste. Franklin’s prudent rule was to leave off eating with a good appetite.
Economy of the life forces requires that each person should strive to find out just how much food he requires to support his strength and repair the waste. One ounce more than is required is a triple waste,—a waste in the original cost, a waste of muscular force in digesting it, and a waste of nerve and vital force in getting rid of it.
Cereals and Their Food Value.—Dr. H. W. Wiley, Chief of the Bureau of Chemistry in the United States Department of Agriculture, in speaking of the substitutes for meat, says: “In so far as actual nourishment is concerned, the very cheapest and best that can be secured is presented by the cereals, viz., Indian corn, wheat, oats, rye, rice, etc. These contain all the nourishment necessary to supply the waste of the body and the energy and heat necessary to all animal functions and hard labor, in a form well suited to digestion, and capable not only of maintaining the body in a perfect condition, but also of furnishing the energy necessary to the hardest kind of manual labor. The waste material in cereals is very small, and, as compared with that in meats, practically none at all. In fact, the ordinary wastes, such as the bran and germ, are among the most nutritive components of the cereals, and both health and economy would be conserved, as a rule, by their consumption, instead of rejecting them as in the ordinary process of milling. The ordinary cereals of commerce contain only about ten per cent of waste, and this is an exceedingly small proportion, as compared with the percentage in meats.
“If meats should be used more for condimental purposes, as in the making of soups, stews, etc., and not more than once a day, as one of the staple articles of the table, it would be better, in my opinion, for the health and strength of the consumer, and especially would it be a saving in the matter of household expenses.
“It is well known that men who are nourished very extensively on cereals are capable of the hardest and most enduring manual labor. Meats are quickly digested, furnish an abundance of energy soon after consumption, but are not retained in the digestive organism long enough to sustain permanent muscular exertion. On the other hand, cereal foods are more slowly digested, furnish the energy necessary to digestion and the vital functions in a more uniform manner, and thus are better suited to sustain hard manual labor for a long period of time.