Vitamins, Minerals and Dietary Supplements
What is iodine?
Iodine is a trace mineral and essential nutrient. In its natural state, it is grayish-black in color and lustrous in appearance. It is commonly found in sea water; many soils located near coastal areas are also rich in iodine.
Why do we need it?
Iodine plays a crucial role in the normal function of the thyroid gland. It is also essential for the production of thyroid hormones, which in turn are necessary for maintaining normal cell metabolism.
How much iodine should I take?
According to the National Academy of Sciences, the recommended daily allowance (RDA) for iodine is as follows:
- Adult men: 150 micrograms/day
- Adult women: 150 micrograms/day
- Children aged 7-10: 120 micrograms/day
- Infants: between 40-50 micrograms/day
- Pregnant/lactating women: between 175-200 micrograms/day
What are some good sources of iodine?
Iodized salt is the primary food source of iodine. Iodine can also be found in seafood; kelp, cod, sea bass, haddock and perch are particularly good sources. Dairy products and vegetables grown in iodine-rich soil also contain large amounts of the mineral.
What can happen if I don't get enough iodine?
Iodine deficiency is uncommon in Western society; in fact, the typical Western diet contains about four times the recommended daily allowance of iodine. However, people who avoid dairy products, seafood, processed foods and iodized salt can become deficient.
Iodine deficiency can lead to decreased thyroid function, goiter, and cretinism, a condition marked by dry skin, swelling around the lips and nose, and impaired mental function.
What can happen if I take too much?
In addition to being linked to iodine deficiency, some studies suggest that goiter may also be caused by excessive iodine intake. Other studies have linked high amounts of iodine to an increased risk of thyroid cancer.
- Recommended Dietary Allowances, 10th ed. Washington, D.C.: National Academy Press, 1989.
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- Barker DJP, Phillips DIW. Current incidence of thyrotoxicosis and past prevalence of goiter in 12 British towns. Lancet 1984;ii:567-70.
- Williams ED, Doniach I, Bjarnason O, et al. Thyroid cancer in an iodide rich area. Cancer 1977;39:215-22.