February 26, 2009
Iodine Labeling Misleading
U.S. researchers reported Wednesday that multivitamin supplements contain less iodine than the label promises, which could put newborns at risk for developmental issues.
Boston University Medical Center researchers tested the iodine content of 60 multivitamins with iodine. Dramatic findings reveal that only 28 percent contained the full amount promised on the label.The study is published in the New England Journal of Medicine.
In the other cases, researchers found the products designed to prevent iodine deficiency were deficient themselves, including some only available by prescription.
The American Thyroid Association recommends a 150 micrograms per day daily dose for pregnant and lactating women. However, of the 44 products that claimed to deliver that amount, one third had 75 micrograms or less.
Iodine deficiency is the leading cause of preventable mental retardation.
More than 38 percent of the world's population is deficient.
A Chinese study of children with moderate or severe iodine deficiency found that giving them supplements added around 13 points to their long-term IQ score.
Iodine deficiency is a smaller problem in developed countries. However, the problem is growing partly because less salt is being used out of concern for its effect on high blood pressure.
"The amount of iodine in the U.S. diet is still sufficient overall, but it has dropped dramatically, and most dramatically in women of childbearing age. It's their fetuses who are really at risk, and we have no way of identifying individuals who are iodine deficient," said Dr. Elizabeth Pearce of Boston University Medical Center.
Labeling is misleading because in products containing potassium iodide, only 76 percent of the amount stated on the label is available to the body.
Pearce said pregnant women should look for a prenatal multivitamin or supplement with potassium iodide as the source because it is less variable.
"They should use iodized salt if they're adding salt, but probably the best source in addition to the multivitamin is dairy foods," she said.
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