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An essential trace element, iodine is a constituent of the hormone thyroxine, concentrated in the thyroid gland.
Iodine isn't found in the free state, but occurs in saltpetre (potassium nitrate [KN03]) and sea-water.
Some of its best culinary sources are found in kelp, milk, onions, seaweeds and shellfish.
The influence of iodine, through thyroxine, is felt everywhere in the body. It raises the metabolic rate, helping the body to burn off excess fat and preventing the accumulation of cholesterol. Iodine calms nerves and improves the quality of hair, skin nails and teeth.
It accomplishes all this by stimulating the thyroid gland to produce thyroxine.
An under-active thyroid, resulting in iodine deficiency, can cause symptoms such as obesity, rapid pulse, goitre, a cold body, constipation, general weakness, excessive menstruation, low resistance to colds and infections, nervousness and irritability. Iodine deficiency can also increase the risk of breast and uterine cancer.
A study of Japanese women, who normally eat plenty of iodine-rich seafood, has shown that this diet contributed to their lower-than-average incidence of breast cancer.
In cases of an under-active thyroid, or when iodine is being taken as a supplement, raw vegetables of the Brassica family shouldn't be eaten as they block the absorption of iodine.
To supplement iodine take kelp tablets; the normal daily requirement of iodine being 150mcg for adults. See 'Alternative Medicine'