Iodine Content and Quality in Prenatal Supplements is Concerning

Along with iron and folic acid, iodine is among the most critical nutrients needed during pregnancy to ensure normal fetal development, both physically and mentally. Iodine is essential for building a healthy brain, skeleton and metabolism. During the first 14-16 weeks of pregnancy, a fetus is entirely dependent on the mother for its supply of thyroid hormone. Inadequate iodine and thyroid hormone during pre-conception and pregnancy can result in significant mental impairment in the infant. A study published in the New England Journal of Medicine shows that few supplements meet nutritional recommendations for iodine during pregnancy, and few are meeting label claims.

This study raises a number of concerns. Of the 223 prenatal supplements analyzed, about half of them didn’t even contain iodine. Of the ones that did contain iodine, almost 10% had tested iodine levels that were less than 50% of their label claim. Prescription prenatals were not more trustworthy than non-prescription products. The vast majority of products contained significantly less than the 250 mcg/day recommended by the World Health Organization during pregnancy and lactation.

To add to the concern over the quality of the supplements, average dietary iodine intake has been decreasing in most parts of the world making a quality supplement even more important. The latest dietary survey in the U.S. indicated that more than a third of women of child bearing age had iodine levels considered insufficient.

The study is simple to read, and we would suggest turning most of your attention to the table in the article. It sums up the findings and shows you the measured (actual) versus labeled (theoretical) amounts of iodine present in each product.

Leung AM, Pearce EN, Braverman LE. Iodine content of prenatal multivitamins in the United States. N Engl J Med. 2009;360(9):939-40.