IODINE DEFICIENCY

condition in which an organism does not take in enough iodine, an element that directly affects thyroid gland secretions, which themselves to a great extent control heart action, nerve response to stimuli, rate of body growth, and metabolism. Simple goitre (enlargement of the thyroid gland) is the most common form of iodine deficiency illness and is found particularly in mountainous regions and areas far from salt water. Lowest incidence of this disease occurs along seacoasts. When the supply of iodine is only moderately deficient, the thyroid gland works harder to synthesize hormones in normal quantities, but the affected individual may continue in general good health despite the possible presence of goitre. In cases of severe and prolonged deficiency, however, there may be a deficit of thyroid hormones, resulting in myxedema, a condition characterized by dry skin, loss of hair, puffy face, flabbiness and weakness of muscles, weight increase, diminished vigour, and mental sluggishness. Prevention of iodine deficiency is most simply accomplished by eating seafood regularly or by use of iodized table salt. To overcome natural iodine deficits, government health officials in Canada and other nations have made dietary iodine additives mandatory. Sporadic goitre remains a mystery because it occurs in areas where iodine intake is more than adequate. Foods such as cabbage and turnips contain a potentially dangerous progoitrin substance believed to inhibit normal intake of iodine by body tissues. During the heat of cooking, however, the offending enzyme usually is destroyed. A lack of iodine during infancy may cause a condition known as cretinism, in which mental and physical development is severely impaired. This condition can be prevented if the mother maintains a diet of foods high in iodine during pregnancy.