Iodine Supplements Before, During, and After Pregnancy

Although severe iodine deficiency was eliminated in the United States nearly a century ago, after the introduction of iodized salt, iodine intake has declined in recent decades. Public health efforts to limit salt intake to decrease cardiovascular risk, in conjunction with increasing use of non-iodized salt, may in part be to blame.

Now, not adding salt to foods is a good thing, as sodium is considered the second leading dietary killer in the world—second only to not eating enough fruit. But if you do add table salt, make sure it’s iodized, as it is a myth, and often also false advertising, that so-called “natural” sea salt contains significant amounts of iodine.

Fruits and vegetables provide iodine, but the amounts can vary depending on where it’s grown; how much iodine is in the soil. Because iodine is particularly important for fetal brain development, there’s a recommendation that all U.S. women who are pregnant, lactating, or even planning a pregnancy should ingest dietary supplements containing 150mcg of potassium iodide per day.

Is there evidence that they’re not getting enough now? Well, we’d like to see urine levels in pregnant women over 150. But in the U.S., pregnant women only average about 125. For example, a recent survey in New York City showed only about half of pregnant women were making the cut. Don’t most women take prenatal vitamins, though?

Only about half of prenatal multivitamins contain any iodine at all. And so, only about one in five pregnant women in the U.S. are following the recommendations of the American Thyroid Association to take a daily iodine supplement—specifically in the form of potassium iodide rather than seaweed, as the levels in seaweed are subject to natural variability. Though the iodine content was as much as 90% off in some of the potassium iodide prenatal supplements, the kelp supplements varied even wider, off by as much as 170%.

Now, the American Thyroid Association admits they don’t have evidence that the current borderline insufficiency levels are leading to undesirable outcomes, and so, their recommendation that all pregnant women take iodine supplements is a bit tenuous. But until such data are available, they figure better safe than sorry.

A randomized, placebo-controlled interventional trial would answer the question once and for all, but the existing evidence for iodine supplementation during pregnancy is so convincing that it would be considered unethical to randomize pregnant women to a placebo. And so, when it comes to sufficient iodine intake during pregnancy, I’d recommend, just do it.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

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Image thanks to il-young ko via flickr

• iodine
• mortality
• multivitamins
• pregnancy
• prenatal vitamins
• salt
• sea vegetables
• seaweed
• supplements
• thyroid health
• vitamins