32. To feed her family properly, the housewife should understand that
the daily food must include the five food substances--protein, fat,
carbohydrate, mineral matter, and water. As these are discussed in
_Essentials of Cookery_, Part 1, they should be clear to the housewife,
but if they are not fully understood, a careful review should be made of
the discussions given there. The ways in which these food principles
contribute to the growth and health of the body, as well as the ordinary
foods that supply them in the greatest number, are tabulated in Table II
for easy reference. This information will assist the housewife
materially in the selection and preparation of food for her family;
consequently, close attention should be given to it and constant
application made of it.
33. As has already been learned and as will be noted here, a food
substance often has more than one use in the body. For instance, protein
builds tissue and also yields energy, but its chief work is that of
building tissue, and so it is classed first as a tissue-building food
substance. The fats and carbohydrates also have a double use in the
body, that of producing heat and energy and of building fatty tissue.
However, as their chief use is to produce heat and energy, they are
known principally as heat-producing foods. Mineral matter not only is
necessary for the building of bone and muscle, but also enters into the
composition of the blood and all the fluids in the body. Growth and
development are not ideal without an adequate supply of the many kinds
of these salts, which go to make up the tissues, nerves, blood, and
other fluids in the body.
34. The body regulators must be included in the food given, for they
assist in all processes carried on in the body. Some are necessary to
aid in the stimulation required to carry on the processes of digestion
and in some cases make up a part of the digestive fluids. Consequently,
vegetables and fruits that supply these body regulators and foods that
supply vitamines should be provided.
Water, the chief body regulator, not only is essential to life itself,
but forms by far a greater proportion of the body than any other single
substance. The largest part of the water required in the body is
supplied as a beverage and the remainder is taken in with the foods that
are eaten.