On June 5, 2013, the American Thyroid Association (ATA) advised that children and adults, including pregnant and lactating women, consume no more than 500 mcg of iodine daily from iodine and kelp supplements.

While adequate iodine intake is required for normal thyroid function (150 mcg daily for adults and 220-250 mcg daily for pregnant women), the ATA notes that these amounts are usually provided by the typical U.S. diet, and warns that exceeding Upper Limits (UL) for iodine (1, 100 mcg daily for adults) may cause thyroid dysfunction.

(See ConsumerLab.com's Recommended Daily Intakes and Upper Limits For Iodine for children, adults, pregnant and lactating women for more information.)

Infants, the elderly, pregnant and lactating women, and individuals with preexisting thyroid disease are particularly susceptible to the adverse effects of too much iodine. Because most people take in enough iodine through their diet alone, taking over 500 mcg of an iodine or kelp supplement may result in an intake that exceeds ULs.

The ATA recommends that pregnant and lactating women meet their increased need for iodine by taking a multivitamin containing 150 mcg iodine daily in the form of potassium iodide (KI) (3) during preconception, pregnancy and lactation.

Under certain medical and environmental conditions - such as severe hyperthyroidism or exposure to radiation from a nuclear power plant accident —taking more than 500 mcg of a daily iodine supplement may be indicated.

See ConsumerLab.com's Reviews of Potassium Iodide (KI) and Potassium Iodate (KIO3): Radioprotective Agents, Multivitamin and Multimineral Supplements, and Kelp Supplements Review for tests of related products.

To read the American Thyroid Association's statement, use the link below.