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Iodine Levels of Many Prenatal Multivitamins Inaccurate

Kelp-containing vitamins often disagree considerably with label

WEDNESDAY, Feb. 25 (HealthDay News) -- Although sufficient maternal iodine is important for normal thyroid and neurological function, many prenatal vitamins available in the United States that claim to contain iodine do not carry the amount indicated on the label, according to a letter published in the Feb. 26 issue of the New England Journal of Medicine.

Using the Internet, Angela M. Leung, M.D., and colleagues from Boston University Medical Center identified 114 prenatal multivitamins (prescription and non-prescription) currently available in the United States that contained iodine according to the product label. They then measured the iodine content of 60 randomly selected prenatal vitamins.

Of the 35 potassium iodide-containing vitamins, the researchers found that the mean daily dose contained 119 μg of iodine, the equivalent of 76 percent of the total potassium iodide content. Of the 25 kelp-containing vitamins, the daily dose contained iodine levels ranging from 33 to 610 μg, the researchers report. About half of these disagreed with the labeled iodine content by 50 percent or more.

"Manufacturers of prenatal multivitamins in the United States should be encouraged to use only potassium iodide, to maintain consistency in labeling, and to ensure that these vitamins contain 150 μg of supplemental daily iodine by including at least 197 μg of potassium iodide per daily dose, as recommended by the American Thyroid Association," Leung and colleagues conclude.

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