The chief store-house of iodine in the body is the thyroid gland. The essential thyroxine, which is secreted by this gland, is made by the circulating iodine. Thyroxine is a wonder chemical which controls the basic metabolism and oxygen consumption of tissues. It increases the heart rate as well as urinary calcium excretion. Iodine regulates the rate of energy production and body weight and promotes proper growth. It improves mental alacrity and promotes healthy hair, nails, skin, and teeth.

The best dietary sources of iodine are kelp and other seaweeds. Other good sources are turnip greens, garlic, watercress, pineapples, pears, artichokes, citrus fruits, egg yolk and seafoods and fish liver oils. The recommended dietary allowances are 130 mcg. per day for adult males and 100 mcg. per day for adult females. An increase to 125 mcg. per day during pregnancy and to 150 mcg. per day during lactation has been recommended. Deficiency can cause goitre and enlargement of the thyroid glands.

Small doses of iodine are of great value in the prevention of goitre in areas where it is endemic and are of value in treatments, at least in the early stages. Larger doses have a temporary value in the preparation of patients with hyperthyroidism for surgical operation.