Iodine is the nonmetallic element with the chemical symbol I. However; it is most commonly found in the bivalent ionic form iodide, I++.
The average adult human body contains about 20 mg. of iodine, 70-80% of which is concentrated in the thyroid gland. Even though the quantity of iodine in the human body is so small that it is classified as an ultra-trace mineral, iodine is essential to life. One way or another, directly or indirectly, iodine plays a significant role in many different human body functions.
Iodine is an essential component of the thyroid hormones, T3, and T4, which regulate body metabolism. Without iodine, normal functioning of the thyroid gland cannot occur. Iodine is also a necessity for energy production and healthy growth and development. Since the food serves as the primary source, adequate dietary intake is a must at all stages of life. Pregnant women who are iodine deficient pass the syndrome along to their developing babies who, if they survive the fetal stage, are likely to be born with serious mental and physiological abnormalities. The brain, heart, kidneys, pituitary gland, and muscles all depend on iodine.
Today severe iodine deficiency is almost non-existent in the United States due to the ready availability of iodized salt. However, it continues to be a major health problem in underdeveloped countries and in mountainous regions and lowlands where the iodine and selenium soil content is low. Selenium enters into the equation because of its important role in iodine metabolism.