Page:Food and cookery for the sick and convalescent.djvu/25

Rh contains all the food principles, it is possible to sustain life on proteids, mineral matter, and water.

Proteids are the most expensive foods, and there is often found to be an insufficient quantity in dietaries, especially among the poorer classes. It is conceded to be true, that in the United States with those of large incomes there is a tendency to an excess of proteids, but this does not apply to the average American family. Our people eat more than any other people, and do correspondingly more work. The growing child suffers more from the lack of proteid than the adult, as much material is required for building as well as repair. Until recently it was supposed that metabolism went on much faster in young cells, but now the greater activity of the child is held responsible for these rapid changes.

The chief office of carbohydrates is to furnish heat and energy and store fat. They contain carbon, hydrogen, and oxygen, the hydrogen and oxygen always being in the proportion to form water (H2O).

Starch, the chief source of carbohydrates, abounds throughout the vegetable kingdom, being obtained from seeds, roots, tubers, stems, and pith of many plants. Examples: cereals, potatoes, sago, tapico, etc.

Sugars, the other source from which carbohydrates are obtained, are classified as follows: —

Carbohydrates include the cheapest kinds of foods and are apt to be taken in excess. In institutions where large numbers are fed there is a tendency in this direction.