Iodine in food
Our bodies must have an adequate intake of iodine to form the hormones produced by the thyroid gland. These hormones regulate our bodies' metabolic rate. If the dietary level of iodine is inadequate, the gland, which is in the neck, swells and produces goitre. Unless treated, this condition can cause mental retardation and stunted growth in children, and hair loss, slowed reflexes, dry, coarse skin and other effects in adults. Foods produced in regions where soils are low in iodine, such as Tasmania in Australia, the Thames Valley in the U.K., and the north-west region of the U.S.A., are deficient in this element. Goitre caused by iodine deficiency can be prevented by supplementing the diet with added iodine. This is commonly done by adding sodium iodide to table salt to produce iodized salt. For some people, iodized salt can be an important source of iodine, and a change to a low-salt diet should make allowance for the decrease in iodine intake. Some foods, such as cabbage, sprouts and other brassicas contain natural anti-thyroid substances. In circumstances where both large quantities of these foods are eaten and the levels of dietary iodine are marginal, goitre could develop.