FOOD AND ITS USES

Food is anything which nourishes the body, and is necessary
_ for growth, repair, heat and energy, and to pegaty body pro-
cesses.

After it is taken into the body, all food must undergo certain
chemical changes before it can be used by the body, and this is
the work of the digestive system.

Foods are Classified as:

1. Protein—This is the great building material. Other
foods give heat and energy, but protein is the only one which
builds up and repairs the body, and is therefore essential.

_ Foods which are high in protein are milk, meat, fish, eggs,
peas, beans and lentils. The cereals and vegetables other than
the legumes, contain a considerable amount.

2. Carbohydrate—This is divided into two groups: sugars

and starches. These supply heat and energy and may be con-
verted into fatty tissue. The source of the starches is mainly the
cereals, and certain vegetables. Cellulose is a form of carbo-
hydrate, but is not digested in the body. It is necessary*in the
diet because it gives bulk to the food passing through the
intestines, and so prevents constipation. Most vegetables are a
prolific source of cellulose.

3. Fats—These supply heat in a concentrated form, giving
214 times as much as carbohydrate. They are from animal or
vegetable sources.

4. Mineral Matter—These supply building material and
help to regulate body processes. The most important are
calcium or lime, chlorine, iron, sulphur, phosphorus, potassium,
magnesium and iodine. They are small in bulk, but of the utmost
importance; especially during the growth period. The principal
sources are: milk, butter, eggs, greens, fruits, vegetables, and
whole grain products.

5. Vitamins—These are found in very minute quantities
- in certain foods, and are absolutely necessary for the prevention