Page:Food and cookery for the sick and convalescent.djvu/23

 OOD is that which builds and repairs the body, and furnishes heat and energy for its activities. Metabolism includes the processes by which food is assimilated and becomes part of the tissues, and the excretion of broken-down tissues as waste products. The body, by the analysis of its different organs and tissues, is found to contain from fifteen to twenty chemical elements, of which the principals are: carbon (C), 21½%; hydrogen, (H), 10%; oxygen (O), 62½%; and nitrogen (N), 3%. Phosphorus (P), sulphur (S), iron (Fe), chlorine (CI), fluorine (Fl), calcium (Ca), potassium (K), sodium (Na), magnesium (Mg), and silicon (Si) are some of the others present. The elements found in the body must be supplied by the oxidation and utilization of the food stuffs, and the health of the individual will suffer if these are not properly maintained.

Food adjuncts are such substances as stimulate the appetite without fulfilling the requirements of food. Examples: tea, coffee, spices, flavoring extracts, condiments, etc., etc.

While air is not classified as a food, it is essential to life. Combustion cannot take place without it, and all food must be oxidized (which is a process of slow combustion) before it can be utilized by the body.