Importance of Iodine for the human body
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Iodine is an essential micronutrient required for the synthesis of the thyroid hormones, thyroxine and triiodothyronine containing respectively four and three atoms of iodine. It is necessary in minute amounts for the normal growth and development and well being of all humans. The composition of iodine in adults is about 50 mg and the blood level is bout 8 to 12 mcg /dl.

Iodine is a component of all the cells in the body but 80 per cent of the total mineral is stored in the thyroid gland. Its level in the blood is 5 to 10 ug /dl. It is found in low quantity in the upper regions of mountains. Such areas are called goiterous belts. The program of iodination of common salt has resulted in increased availability of the mineral element.

The absorption of iodine is mainly from small intestine and it may also be absorbed through the skin. Toxic manifestations may result from prolonged use of iodine containing skin ointments. Ingredients in food stuffs that prevent its utilization are called goiterogens.

Benefits of Iodine:

The only biological role of the nutrient is in the formation of thyroid hormones, thyroxin and tri-iodothyronine. Iodine plays a significant role in the basic processes of metabolism in the body, due to its influence on the thyroid hormone. It helps the body to efficiently burn calories and prevents the storage of fat. It contributes towards increasing the body’s energy levels and keeps them enhanced. It leads to the development of healthy skin, teeth, hair and nails. It helps destroy the harmful effect of toxins in the body and helps in the utilization of calcium and silicon.

Sources of Iodine:

The best sources of Iodine are sea foods such as sea fish, sea salt and cod liver oil. Smaller amounts of the nutrient occur in other foods such as milk, meat, vegetables, cereals etc. The iodine content of fresh water is small and variable, about 1 to 50 mcg l. About 90 per cent of the mineral comes from foods eaten and the rest comes from drinks and water. The iodine content of the soil determines its presence in both water and locally grown foods. The deficiency is geo chemical in nature. 

Goitrogens:

These are chemical substances leading to the development of goiter. They interfere with iodine utilization by the thyroid gland and may occur in food and water. The brassic group of vegetables such as cabbage, cauliflower etc, may contain goitrogens. Most important among the dietary goitrogens are probably cyanoglycosides and the thiocyanates.

Iodine Deficiency:

The most obvious consequence of iodine deficiency is goiter but recent studies have indicated that there is a much wider spectrum of disorders some of them are extremely severe and may result in permanent disability. These include hypothyroidism, retarded physical development and impaired mental function, increased rate of spontaneous abortion and still birth, neurological cretinism including deaf mutism and nyxedematous cretinism, including dwarfism and severe mental retardation. To express this more accurately the term, ‘endemic goitre’ is now replaced by the term Iodine Deficiency Disorders (IDD). According to a survey conducted by world Health Organization (WHO), Iodine deficiency is one of the lading causes of mental retardation across the globe.

Requirement in the human body:

The daily requirement of the nutrient for adults is placed at 150 mcg / day. This amount is normally supplied by well balanced diets and drinking water except in regions where food and water are deficient in iodine.

Iodine was discovered by B Courtois in 1811 and isolated in 1819 by Fyfe. In 1896, E Baumann found that the thyroid gland contained substantial amounts of the nutrient in comparison to other tissue in the body.