The American Thyroid Association recommends prenatal vitamins with 150 mcg elemental iodine during pregnancy. The Institute of Medicine recommends 220 mcg iodine in pregnancy, and 290 mcg when breast feeding. There is no mandate for U.S. prenatal vitamins to have 150 mcgs of iodine.
What does a pregnant women do to insure her baby is getting enough iodine?
The internet listed 127 nonprescription, and 96 prescription brands on the market in the U.S. Only 69% of non-RX brands had iodine listed. Even lower percentage of prescription brands listed iodine. 90% of them with iodine, listed > 150 mcg of iodine. 150 mcg of KI is only 114 of elemental iodine. Kelp based prenatal vitamins had >150 mcg iodine. This labeling is misleading. Researchers at Boston University measured 60 brands of prenatal vitamins for iodine content. The prenatal with KI had 119 mcgs as expected.
However, the kelp based prenatal had 33-610 mcgs of iodine. Over half had content that was different than listed on the label, including 10/25 with low iodine content. Kelp iodine content is variable, and one should stick to potassium iodide KI as the source of their prenatal iodine, not kelp.
1. 69% of non-RX prenatal, and 28% of prescription prenatal vitamins have iodine.
2. Kelp is a poor source of iodine due to variable amounts of iodine.
3. KI based prenatal is more consistent but only have 76% iodine content of the labeled 150 mcg, or 120 mcgs.
4. KI prenatals should be the drug of choice.
5. However future prenatal vitamins should have 197 mcg KI to get to the recommended 150 mcgs elemental iodine supplement needed during pregnancy, and lactation.
What should the woman do now?
Get KI based Prenatal vitamins, and add a 100 mcg KI pill, to get the extra 80 mcgs you need.
Good Luck with the pregnancy,
Iodine Content of U.S. Prenatal Multivitamins
Leung, et al
American Thyroid Association national meeting abstract #106
Thyroid supplement page S-45
October 3 2008.