Changes in diet and lifestyles are contributing to iodine deficiency in the United States

A study published this week in the Journal of Nutrition has drawn our attention to a historical problem that is re-emerging across the United States. The study finds that iodine inadequacy is prevalent and nearly doubled from 2001 to 2018.

The study shows that increasing proportions of vulnerable groups, women of reproductive age and pregnant and minority women, did not meat the Estimated Average Requirement (EAR) for iodine during that period. The study cites changes in production and processing of major dietary iodine sources, especially iodized salt, dairy and bread, as the causes of reduced iodine intake.  Some 46% of pregnant women in 2017-2018 had inadequate intake.

“Given the current state of iodine nutriture, and likelihood of continuing decreases of iodine intake in the US, effective educational and regulatory measures appear essential, especially to protect pregnant and minority women and their offspring”, the article notes.

The study used data from the National Health and Nutrition Examination Survey (NHANES) collected in 2001-2018 as a basis for its conclusions.

2024 was the 100^th anniversary of salt iodization in the United States and gave IGN North American Regional Coordinator Dr. Elizabeth Pearce an opportunity to raise awareness of the problem. She is also working with the National Dairy Council to reach dietitians, dairy scientists, food influencers, consumers, and healthcare providers with presentations at national and regional meetings, webinars, and podcasts, emphasizing the role of dairy as an iodine source, particularly considering rising consumption of non-dairy alternatives.

“The U.S. Dietary Guidelines Advisory Committee (DGAC) recognizes iodine as a nutrient of concern in the draft scientific report for the 2025-2030 U.S. Dietary Guidelines, particularly for pregnant women, lactating mothers, and women of reproductive age. This inclusion highlights growing evidence of inadequate iodine intake in key population groups and the potential public health implications of iodine deficiency”, said Dr. Pearce.

IGN is also engaged with a multi-center cross-sectional survey of US pregnant women that is taking place in collaboration with investigators at Michigan State as part of ECHO, a national NIH-funded pregnancy cohort collaborative. “IGN is supporting additional analysis of a representative sample of pregnant women from Michigan (which was the most profoundly iodine deficient US region prior to salt iodization). When available, IGN will use this new iodine status data from U.S. pregnancy cohorts to advocate globally for stronger policies and public health interventions”, said IGN Executive Director Dr. Werner Schultink.

He also noted that the study’s conclusions reflected the findings of the recent WHO/IGN report on iodine deficiency in Europe, and that this is a worrying trend that is being observed in both rich and poor countries.

A story and a leader article in The Economist earlier this year also drew attention to the issue.