Iodine Factoids

• Iodine is the nonmetallic element with the symbol I, most commonly found in its bivalent ionic form, I++.In the human body, where iodine is concentrated primarily in the thyroid gland, the amount is so small that it is classified as an ultra-trace mineral. Nevertheless, iodine is essential to life.

• Iodine got its name from the Greek word “iodes,” which means violet. Iodine in the gas state is violet colored.

• Iodine is an essential component of the thyroid hormones T3 (with 3 iodine atoms per molecule) and T4 (with 4 iodine atoms per molecule). Since these two thyroid hormones regulate the metabolism of the body, without iodine, the thyroid gland could not function normally. Iodine is also necessary for normal growth and development and proper functioning of the immune system.

• Proper iodine metabolism also depends on selenium. People who live in a region where the soil is deficient in either iodine or selenium are more susceptible to iodine deficiency.

• Severe iodine deficiency, while a problem in some countries, is extremely rare in the United States, due to the widespread availability and use of iodized table salt. A mere ¼ teaspoon of iodized table salt contains about 100 mcg of iodine, which is already a substantial percentage of the Recommended Dietary Allowance (RDA) of 150 mcg per day for adults. Children and pregnant and lactating women need more iodine, 200-300 mcg day for children and 220 mcg and 290 mcg per day, respectively, for pregnant and lactating women.

• Apart from iodized table salt, other good dietary sources of iodine include sea salt (but with only 1/10 as much iodine), shellfish, sardines, other salt water fish, canned salmon, and seaweed, along with milk and milk products, eggs, and yeast. Breads and other commercially baked products are good sources as well, due to the addition of iodate dough conditioners.

• Among healthy individuals, the absorption of dietary iodine is highly efficient, in excess of 90%. Even so, it is practically impossible for iodine toxicity to be the result of diet alone. The usual cause of toxicity is an excessive intake of iodine supplements.

• Cruciferous vegetables, like cabbage, kale, cauliflower, and Brussels sprouts, contain substances called goitrogens, which interfere with iodine metabolism and thus inhibit thyroid hormone production. Individuals with a thyroid problem need to watch their intake of these foods, along with soy foods, which contain isoflavones, which can also affect thyroid gland functioning.

• Individuals with goiters (enlarged thyroid gland) and impaired thyroid functioning are commonly treated with iodine supplements.  Goiters are more prevalent in women than in men and in the elderly.

• Infants, more than any other age group, are susceptible to the effects of iodine deficiency. Therefore, adequate dietary intake of iodine is absolutely critical during pregnancy. Pregnant women who are iodine deficient pass on the deficiency to their developing babies who, if they survive, are likely to be born with severe mental and physiological abnormalities, including cretinism. Pregnant and lactating women are frequently prescribed iodine supplements as an extra precautionary measure.

• Because iodine is an ultra-trace mineral, there is a narrow range in the amount of iodine intake that is optimal for each individual. Iodine intake that is significantly either less than or greater than that optimum amount can create serious problems. Paradoxically, iodine deficiency and iodine toxicity can produce some of the same symptoms. Either condition can result in a goiter, elevated TSH levels, and either hypothyroidism or hyperthyroidism. This is due to the fact, that in both cases the thyroid gland is being overstimulated.

• Sometimes overaggressive treatment of iodine deficiency has the unwanted effect of creating a new problem of iodine toxicity. This chain of events, which is most likely in elderly patients, is called jodbasedow.