Proteins have four calories per gram and are the most slowly absorbed foods. Until the early

1980s, fats were considered to be the slowest-absorbing of the three food groups. Research

from a university on the East Coast determined otherwise. Proteins have a greater than 50

percent capability of being changed into glucose. While fats must be changed into ketone

bodies before being used as an energy source, proteins need only to be changed into glucose.

All animal sources contain protein. This includes dairy products, meats, and fish. Vegetable

plant sources contain protein, but in varying amounts. Grains also contain protein.

Other Nutrients

Other nutrients are also important in meeting the needs of the human body. Nutrients are

found both in minerals (such as iron and calcium) and in vitamins (as in A, B1, B2, B3, C,

D, and so forth).

Along with the three food groups, nutrients are needed as an energ source and are used for

growth and repair of body tissue. Althoug there are roughly 50 nutrients needed for daily

growth and development, only the major vitamins and minerals are discussed here.

Iron is the carrier of oxygen to body tissues. Anemia is prevented through adequate iron in

the diet. Calcium is used for building strong bones and teeth; it is also used in muscle

contraction and relaxation and in the proper functioning of the nerves. Vitamin A is known

for its role in promoting good vision. Its lesser but still important role is in keeping the

skin and mucous membranes in good condition.

Vitamin B1 aids in digestion and in muscle and nerve function. B2 helps in promoting healthy

skin and mucous membranes and general vitality. B3 aids in digestion, keeping the nerves and

skin in good condition. Vitamin C has many more roles than was thought earlier. It helps not

only in the healing processes but also in maintaining healthy gums, bones, tissues, blood,

and blood vessels. Vitamin D assists in the utilization of calcium and in the maintenance of

healthy bones.