given to any substance which,
taken into the body, is capable of performing one or more of the
following functions:

1. Building and repairing tissue, maintenance, growth, and development
of the muscles, bones, nerves, and the blood.

2. Furnishing the energy for the internal and external work of the
body.

3. Regulating the body processes, maintaining the proper alkalinity
and acidity of the various fluids throughout the body, regulating the
proper degree of temperature, and determining the osmotic pressure,
etc.

For the convenience of study scientists have arranged the foodstuffs
in groups:

1. According to type;

2. According to their chemical composition;

3. According to the function they perform in the body.

All foods are composed of certain chemical elements; namely, carbon,
oxygen, hydrogen, nitrogen, sulphur, phosphorus, iron, magnesium,
potassium, chlorine, sodium, calcium, with traces of various others.
The manner in which these elements are combined and the amounts in
which they occur determine the group to which the combination belongs,
and give to the foodstuff its characteristic position in human
nutrition.

COMPOSITION OF THE FOODSTUFFS

The chemical elements are combined in food and in the body, as: (a)
carbohydrates, composed of carbon, oxygen and hydrogen; (b) fats,
composed of carbon, oxygen and hydrogen; (c) proteins, composed of
carbon, oxygen, hydrogen, nitrogen and sulphur; (d) water, composed of
hydrogen and oxygen; (e) mineral salts. The first three foodstuffs
constitute the Organic Food group. The last two include the remaining
chemical elements, calcium, phosphorus, sodium, potassium, chlorine,
magnesium, iron and traces of others which make up the Inorganic Food
group.

Each of the foodstuffs belonging to the organic group is capable of
being burned in the body to produce heat for: (a) the maintenance of
the body temperature; (b) internal and external work.

Neither water nor mineral salts alone can be burned to produce heat;
nevertheless, they enter into the composition and take part in every
function performed by the carbohydrates, fats and proteins; therefore
one foodstuff cannot be said to be of greater importance than another,
since the needs of nature are best met by a judicious combination of
all. However, the wear and tear of life can be more efficiently
accounted for, and the strain upon the organism reduced more nearly to
a minimum when the various foodstuffs