Study shows US iodine deficiency rates doubled since 2002

In 2017 and 2018, 24 percent of women and 30 percent of men aged 14 and older in the United States were not getting enough iodine, according to a report published in the Journal of Nutrition in 2025. That figure is about twice as high as the levels recorded in 2001 and 2002. Nearly half of pregnant women across the country have recently fallen short of adequate intake for the nutrient.

Key Clinical Takeaways:
• An estimated 24 percent of women and 30 percent of men aged 14 and older lacked adequate iodine in 2017 and 2018, doubling the deficiency rate from 2001 and 2002.
• The U.S. recommended dietary allowance for iodine is 150 micrograms daily for adults, increasing to 220 mcg for pregnant individuals and 290 mcg for those breastfeeding.
• Only 53 percent of table salt sold in U.S. stores is iodized, while most commercial prepared and processed foods use noniodized salt.

The Disappearing Safety Net Around Iodized Table Salt

Grocery store shelves feature specialty options like Himalayan, kosher, and sea salt, which have largely eclipsed the public health measure of basic iodized table salt. Iodine is a necessary component of thyroid hormones that supports fetal and early childhood brain development. Voluntary salt iodization began in Michigan in the spring of 1924 after high rates of enlarged thyroid glands, known as goiters, were documented across the Northwest, Great Lakes, and Appalachian regions. By the 1950s, goiters had dropped precipitously nationwide.

Modern dietary habits have altered that trajectory. Only 53 percent of table salt sold in U.S. stores is iodized. Most prepared, processed, and packaged foods are manufactured using noniodized salt. Dairy products can supply iodine through animal feed and udder cleansers, but concentrations vary widely, and diets restricting dairy eliminate that source.

Vulnerability During Pregnancy and Early Development

The Centers for Disease Control and Prevention stated in its 2026 Nutrition Report that women of reproductive age in the U.S. population are on the cusp of mild iodine deficiency. Elizabeth Pearce, an endocrinologist at the Boston University Chobanian & Avedisian School of Medicine, noted that even mild degrees of iodine deficiency during pregnancy may be associated with measurably lower IQ in children. The American Thyroid Association and the American Academy of Pediatrics recommend that pregnant and breastfeeding individuals, as well as those planning to become pregnant, take a daily supplement containing 150 micrograms of iodine.

Globally, 126 countries mandate salt iodization, while 21 maintain voluntary policies. An observational study published in Nature Food in September examined an iodine crisis in Ethiopia, where a border conflict with Eritrea in 1998 interrupted the supply of iodized salt. By 2005, up to 40 percent of school-aged children and 36 percent of women of reproductive age in Ethiopia had developed goiters, and child mortality in rural areas reached 25 to 30 percent before mandatory iodization resumed in 2012.

The U.S. recommended dietary allowance stands at 150 micrograms per day for adults, 220 micrograms for pregnant individuals, and 290 micrograms for those breastfeeding. One teaspoon of iodized salt contains approximately 300 micrograms of added iodine. Monica Serrano-Gonzalez, a pediatric endocrinologist at Hasbro Children’s and Brown University’s Warren Alpert Medical School, noted that while moderation in sodium intake remains important, individuals require a small amount of iodized salt to maintain proper thyroid function.

Disclaimer: The information provided in this article is for educational and scientific communication purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider regarding any medical condition, diagnosis, or treatment plan.