By foodstuffs are meant the chemical elements appropriated by the animal for the use of the body, as previously described.
By foods are meant those articles of diet found in the market which contain the chemical elements used by the body in various combinations. Bread, for example, contains all of the foodstuffs and has been called the staff of life, because it sustains life. This refers to bread made from the whole of the grain. White bread, as commonly eaten, is not the “staff of life.”
Foods may contain elements, not foodstuffs, and not used by the body, but cast out as waste. Certain foods, such as sugar, corn-starch, olive oil, and egg albumin, contain only one foodstuff, as will be noted in the following classification, in which the foodstuffs are grouped according to the body uses.
The classification of foods is based on the principal organic foodstuffs they contain. The preponderance of the elements in any one food determines its chief use in the body.
It will be remembered that the chief uses of foods are to produce heat and energy, to build the tissue of the growing child, and to repair the tissues in the child and the adult.
Nearly all foods are made up of a combination of substances.
The following tabulations give the classification of foods based on their predominating elements.
Nitrogenous foods:
Lean meat
Eggs
Gluten
Carbonaceous foods: