A consideration of the kinds of food to meet the different needs of the body follows:
A. Food for Energy.—Although both starch and sugar are carbohydrates which furnish energy to the body, this need of the body should be supplied for the most part by starch. The harmful effects of excessive sugar eating were mentioned previously.
A certain amount of fat is needed for energy-giving. A meal containing fat "stays by" a person for a longer time than one devoid of foods rich in fat. This is because fat is more slowly digested than other foodstuffs. Hence a vigorous person leading an active outdoor life may feel much more comfortable when fat is included in his diet. On the other hand, those exercising little find that fat-rich foods distress them greatly, since they are too slowly digested. For many persons, the use of much fat is harmful. Since butter contains the fat-soluble vitamine, it is valuable not only for energy-giving, but for growth-promoting.
B. Food for Body-building and Repairing.—Both protein and ash are needed for body-building. The former foodstuff contains the element nitrogen,—one of the necessary elements for the growth and maintenance of the body.
Since there are several kinds of food containing protein, the question arises whether protein is best supplied by meat, eggs, milk, cheese, or vegetable protein foods. There are some who contend that meat is the least desirable source of protein food. The use of much meat may lead to the formation of an excess of uric acid which is eliminated by some persons with difficulty. It may also cause intestinal putrefaction.
Many find that by using meat once a day their health is normal. Others find that by using meat but several times a week a more desirable condition is maintained. Doubtless many people would find themselves much benefited by using less meat. If the quantity of meat eaten is greatly lessened, care should be taken that protein is supplied by other foods, such as eggs, legumes, cheese, and the various meat-substitute dishes. Care should also be taken to see that complete proteins are included in diet. If foods containing incomplete protein such as some of the legumes and cereals are used for body-building, they should be supplemented by foods rich in complete protein such as milk and eggs. If much meat is eaten, a generous quantity of water and of fresh vegetables and fruits should be used.
While all the mineral materials found in the body [Footnote 71: The ash constituents existing in the body in largest quantity are:
Sulphur Chlorine Calcium Iron
Sodium Magnesium Potassium Phosphorus
] are necessary for its growth and maintenance, calcium, phosphorus, and iron are the elements most likely to be used in insufficient quantities (see Figures 78, 79, and 80).
[Illustration: FIGURE 78.—FOODS CONTAINING CALCIUM. a, Dried beans, b, dried figs; c, rutabaga, d, celery; e, milk; f, cauliflower, g, almonds; h, egg yolk; i, cheese]