Iodine deficiency is the largest preventable cause of brain-development problems worldwide. The trace mineral is essential for making thyroid hormone, and shortages during pregnancy can harm a baby's developing brain.
In the US, iodized table salt largely wiped out severe deficiency after it was introduced in the 1920s. But recent surveys point to a quiet resurgence, especially in pregnant women, who are now considered mildly iodine deficient. The American Thyroid Association advises women who are pregnant, planning to become pregnant or breastfeeding to take a daily supplement containing 150 mcg of iodine.
Why the shortfall is coming back
Sea salt, kosher salt and Himalayan salt are not usually iodized. Dairy, the other major US iodine source, is losing ground to plant-based alternatives. One analysis of cow's milk found that a single cup provides 57% of a pregnant woman's daily iodine needs, while plant-based milks contained only a small fraction because manufacturers rarely fortify them with iodine.
8 signs of low iodine
Most warning signs trace back to hypothyroidism, meaning the thyroid does not produce enough hormone.
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- Goiter, a visible enlargement of the thyroid at the front of the neck. It is often the first outward clue.
- Fatigue and weakness, as low thyroid hormone slows metabolism across the body.
- Unexplained weight gain, even when eating and activity are unchanged.
- Feeling cold when the people around you are comfortable.
- Constipation and a generally slower digestive rhythm.
- Dry, scaly skin and coarse, thinning hair, which the Cleveland Clinic lists among common signs.
- Puffiness in the face and hoarseness, flagged by the same source in more advanced cases.
- Confusion and difficulty concentrating in adults, and lower-than-average IQ in infants and children exposed during development.
Who is most at risk
Pregnant women top the list. The World Health Organization recommends 250 mcg per day during pregnancy, while the NIH Office of Dietary Supplements sets the US Recommended Dietary Allowance at 220 mcg for pregnancy and 290 mcg for breastfeeding, compared with 150 mcg for other adults.
People who use only non-iodized specialty salts are another quiet risk group, as are vegans and vegetarians who avoid dairy, eggs and seafood. Anyone with a gastrointestinal condition that limits absorption can also fall short.
Where to get iodine
The most reliable dietary sources, according to Harvard's Nutrition Source, are iodized table salt, dairy, eggs, seafood such as cod and shrimp, and seaweed like nori and kelp. Anyone worried about their intake, especially before or during pregnancy, should raise it with a doctor before starting supplements, because getting too much iodine can also disrupt the thyroid.
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This article is made and published by Emil Martesen, who may have used AI in the preparation.