by Darcia Helle

Created on: April 17, 2009

Iodine is a non-metallic trace element detected in every organ and tissue in the human body.

Our body should consistently maintain between 20 and 30 milligrams of iodine. While sources vary on the exact amount, most believe that approximately 60- to 75-percent of this iodine is concentrated in the thyroid gland. The remaining iodine is found mainly in the fluid that bathes our cells.

Necessary for the health of the thyroid gland, iodine is an integral part of the thyroid hormones thryroxine and triiodothryonine. These hormones aid in the regulation of circulatory activity, physical and mental growth, the functioning of the nervous and muscular systems, and the metabolism of all nutrients.

In the event of a nuclear accident, iodine supplements are used in order to prevent the thyroid gland from absorbing the radioactive iodine. This process is thought to protect the body from thyroid damage and possibly from thyroid cancer.

Iodine deficiency is considered one of the most common causes of preventable brain damage in the world. According to the World Health Organization (WHO), iodine deficiency disorders (IDD) affect 740 million people throughout the world. Nearly 50 million people suffer from some degree of IDD-related brain damage.

Iodine deficiency has become rare in developed countries since the introduction of iodized table salt. In the 1990's, major international efforts began to dramatically reduce the occurrence of iodine deficiency in the more iodine-deficient countries. They have done so mainly through the use of iodized salt. At least 70% of households in the world today now regularly use iodized salt.

Areas within the U.S. where iodine deficiency is most prevalent are referred to as goiter belts. These areas include the Midwest, the Pacific Northwest, and the Great Lakes region. The higher deficiency rate is believed to be due to soil conditions.

The classic sign of iodine deficiency is goiter, a condition in which the thyroid gland becomes enlarged as a result of insufficient hormone production.

In rare instances, goiter can be a result of ingesting large amounts of goitrogens, which are substances that decrease the production of thyroid hormones by preventing the utilization of iodine. Foods containing goitrogens include rutabagas, strawberries, peaches, peanuts, soybeans, spinach, cabbage, turnips, and radishes. Cooking these foods generally inactivates the goitrogens.

The richest sources of iodine are fish, shellfish, and sea vegetables (seaweed). Most land vegetables are a poor source of iodine, unless they are grown near a seacoast or in areas where iodine-containing fertilizers are used.

An intake of up to 1,000 micrograms of iodine per day is considered safe. Extremely high doses (20,000 micrograms or more daily) can cause a condition known as iodide goiter. This is seen in certain groups of Japanese who consume large quantities of seaweed on a daily basis.

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