Old age brings a body that is gradually wearing out. This occurs naturally but is hastened by work- or anxiety-strains or earlier illnesses. Many body-processes become slower. Health in age requires increased oxygen-supply, simple diet and life, and exercise according to individual conditions.

Some body-organs lose power to function fully - the heart usually does; others may degenerate and lessen disease-resistance or cause illness. The kidneys act sluggishly and are unable to throw off so readily fluids and salts. Salt should be lessened in the diet. If the waste products of body-metabolism are not completely eliminated, they become poisons. The food-intake in age, especially of protein, should not be more than P, 70 gms.; F,140 gms.; CH, 90-160 gms. (Hirschfeld); that is, P, 2 1/2 oz.; P, 4 3/4 + oz.; CH, 3-5 oz.

Body-deterioration usually includes hardening of the arteries. If extreme, less water is advisable, as dilation of inelastic vessels produces overstrain. When arteries harden, foods with lime are inadvisable. For Lime in Food, see p. 219.

Diseases of the respiratory tract are also a general danger in old age. (Scott's "The Road to Healthy Old Age.")

Human bodies, like animal, tend to increase fat with age. Excess fat interferes with body-processes and causes physical degeneration. Obesity is therefore to be avoided. Diet needs to be selected to prevent corpulency; less food is needed. Water taken with food increases body-fat; at noon not more than half a glass should be taken; at night none until 1 1/2 hours after eating. The evening meal should be very light and without bread, preferably of only one food, either vegetable or fruit. Sleep should not follow eating immediately, for body-secretions are then inactive, so food fails to digest.