Iodine content of prenatal multivitamins

 Iodine deficiency in mothers can adversely affect fetuses and breast-fed infants, because it’s essential for normal thyroid function and development of the nervous system.

Yet, products vary greatly in iodine levels, according to researchers from Boston University Medical Center.

The study was published without an abstract in The New England Journal of Medicine. HealthNews has the details.

The details.

  • Approximately 126 nonprescription and 96 prescription prenatal vitamins are available in the US.
  • Product labeling on 114 products (87 nonprescription and 27 prescription) claimed that the vitamins contained iodine.

And, the results.

  • According to the product labels, 101 (89%) of the prenatal vitamins contained at least 150 mcg of iodine in 1 daily dose.
  • Sources of iodine
    • 67 of the vitamins contained iodine from potassium iodide
    • 42 from kelp
    • 5 from another source
  • Products containing iodine from potassium iodide tended to be more consistent.
  • After measuring actual iodine contained in 60 randomly selected products, 13 had iodine content that differed from that stated on the label by 50% or more.

The bottom line?
The values of iodine are all over the map.

The 610 mcg dose of iodine in some of the multivitamins using kelp is “probably too much,” according to the authors. Although there’s not much supporting evidence for this.

5/6/09 23:27 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.