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.

TABLE II
FOOD SUBSTANCES AND THEIR RELATION TO GROWTH AND HEALTH

I Body-building
materials		Proteins.Meat
Fish and
shell fish
Poultry and
game
Eggs
Milk and
milk products
Legumes
(dried beans,
peas, lentils)
Wheat and
wheat products,
as corn starch
Nuts
Mineral matter,
or ash		Vegetables
Fruits
Eggs
Milk
Cereals
Meats
II Heat-producing
materials		FatsAnimalLard
Suet
Tallow
Butter and
cream
VegetableOlive oil
Corn oil
Cottonseed
oil
Coconut
oil
Nut oils
Mixed
oils		Oleomargarine
Butterine
Nut butter
Crisco, etc.
CarbohydratesStarchCereals and cereal
products
Irish and sweet
potatoes
SugarCane sugar and
molasses
Beet sugar
Maple sugar
and sirup
Honey
Corn sirup
and other
manufactured sirups
ProteinsSame as in I
III Body
regulators		Water
Mineral matter,
or ash		Same as in I
CelluloseFruits
Vegetables
Covering of
cereals
and nuts
Food AcidsSour fruits--citric
and malic
Tomatoes--malic
Spinach--oxalic
Rhubarb--oxalic
VitaminesFat soluble AMilk
Butter
Egg yolk
Water soluble BGreen vegetables, as
spinach, chard,
lettuce, beet greens
Asparagus and stem
vegetables,
as celery
Fruit vegetables,
as tomatoes,
peppers, okra
Fruits

The importance of bulk in foods cannot be emphasized too much. The indigestible cellulose of fruits, vegetables, and cereals is of such importance in the body that some of these foods should be supplied with every meal. Therefore, their incorporation into the diet should be considered as a definite part of the menu-making plan.

The acids of fruits are valuable as stimulants both to the appetite and to the digestion. Then, too, they give a touch of variety to a menu otherwise composed of rather bland foods. The stimulation they produce is much more healthful than that of condiments, drugs, or alcoholic beverages and should receive the preference.

Vitamines are substances necessary for both growth and health. A child deprived of the foods containing them is usually not well and does not grow nor develop normally. These substances are also required in the diet of adults in order to maintain the body in a healthy condition. The leafy vegetables and milk are the foods that yield the greatest supply of vitamines. In fact, it is claimed by those who have experimented most with this matter that these two sources will supply the required amount of vitamines under all conditions.