What Causes Iodine Deficiency, and Who's Most at Risk

Iodine deficiency isn't random — it clusters around specific dietary patterns and life stages. Knowing where you fall on that list is more useful than guessing from symptoms alone.

The Short Answer

Iodine deficiency is caused by consistently low dietary iodine intake — most often from avoiding iodized salt, dairy, eggs, and seafood, the primary dietary sources of iodine. Risk is higher for people following vegan, vegetarian, or unsalted diets, those using non-iodized specialty salts, and pregnant or nursing women, whose iodine needs increase.

Who's Most at Risk

Vegans and Vegetarians

Because dairy, eggs, and seafood are among the richest dietary sources of iodine, people who avoid all animal products need to be more deliberate about getting iodine from iodized salt or fortified foods.

People Using Non-Iodized Salt

Sea salt, kosher salt, and many gourmet salts are not iodized. If iodized table salt isn't part of your routine, it's easy to fall short without realizing it.

Pregnant and Nursing Women

Iodine needs increase during pregnancy and breastfeeding to support both maternal thyroid function and infant development, which is why this group is considered higher-risk for deficiency.

People Eating Fewer Processed Foods

Somewhat counterintuitively, a shift toward whole, unprocessed foods can sometimes reduce iodine intake, since much of the U.S. population's iodine historically comes from iodized salt used in packaged and restaurant food.

Frequently Asked Questions

What causes iodine deficiency?

It's caused by not getting enough iodine from food or supplements over time, most commonly due to low intake of iodized salt, dairy, eggs, and seafood.

Is iodine deficiency common in the United States?

Mild iodine deficiency has become more common in the U.S. in recent decades as iodized salt use has declined and dietary patterns have shifted, though severe deficiency remains uncommon.

Can vegans and vegetarians be iodine deficient?

Yes — since major dietary iodine sources are animal-based, vegans and vegetarians are considered a higher-risk group and often need to plan iodine intake more deliberately through iodized salt or fortified foods.

Who is most at risk for iodine deficiency?

Vegans, vegetarians, people who avoid iodized salt, and pregnant or nursing women are generally considered the highest-risk groups.

This article is for general educational purposes only and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease, and is not a substitute for advice from a qualified healthcare provider — especially if you are pregnant, nursing, taking thyroid medication, or managing a thyroid condition.

Arjun Malhotra researches dietary patterns and risk factors behind iodine deficiency for the Iodine Journal.

This article is part of our complete guide to iodine deficiency.