 Although severe iodine deficiency was eliminated 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 food is a good thing if 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 150 micrograms 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 rationale that all pregnant women take iodine supplements is a bit tenuous, but until such data is 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.