Share of US women and men short on iodine about doubled between 2001-02 and 2017-18
Journal of Nutrition researchers report that 24% of US women and 30% of men aged 14 and up fell short on iodine in 2017-18, about twice the 2001-02 share. Nearly half of pregnant women fell short too, in what Science News calls an estimated, short-term look at population levels.
The Scientist · Science desk
Bar comparison: 30 percent of men and 24 percent of women aged 14 and older were not getting an adequate amount of iodine in 2017 and 2018.
Share aged 14 and older not getting enough iodine, 2017 and 2018
| Item | Value | Claim |
|---|---|---|
| Men, aged 14 and older | 30% | 1 |
| Women, aged 14 and older | 24% | 1 |
What happened
- The CDC's 2026 Nutrition Report states that women of reproductive age are, at the population level, on the cusp of mild iodine deficiency.
- Companies introduced iodized salt in Michigan in spring 1924, and Morton Salt was selling it nationwide by that fall.
- Goiter occurrence had dropped precipitously by the 1950s.
Why it matters
- Who's exposed exposure If the downward trend continues, Science News says, the eventual cost could be more goiters and harm to children's brain development.
- What it limits constraint Iodization was never a federal mandate and began with a Michigan medical society's recommendation, so there is no standing rule to tighten if intake keeps falling.
- What it limits constraint The two survey periods leave out the years between, so the data cannot say when the rise began or whether it is still under way.
Science News gives the earlier comparison only as a rough doubling [2]. Taken at face value, that puts the 2001-02 shares near 12 percent of women and 15 percent of men [15]. The article does not report the earlier figure for pregnant women, or how many pregnant women were in the sample.
The thing this doesn't tell you is how many of those people have any clinical effect. In our view the analysis establishes an intake trend and leaves the health consequence open.
The 30 percent of men below adequate intake in 2017-18 is a share under a nutritional threshold [1]. The goiter counts of a century ago measured something else. In 1918 an examining physician for the World War I draft reported goiters in 30 percent of almost 600 men from one northern Michigan county, some large enough to disqualify them [10]. A 1922 Michigan Department of Health study found goiters in close to 50 percent of schoolchildren in four counties [11].
What iodized salt did on arrival is better documented. A 2017 paper in the Journal of the European Economic Association compared men by birthplace. Among men born in areas without natural iodine sources, World War II Air Force acceptances, based on a qualifying exam, jumped after widespread salt iodization. Among men born where natural sources were adequate, the increase did not occur [12]. The second group is the control. A change in recruiting or testing that applied nationwide would be expected to lift both groups, and an iodine effect predicts a rise in only one.
The clinicians Science News quotes focus on pregnancy. "Even mild degrees of iodine deficiency in pregnancy may be associated with measurably lower IQ in children," said Elizabeth Pearce, an endocrinologist at Boston University Chobanian & Avedisian School of Medicine [13]. The wording is association, and it is about deficiency. The 24 and 30 percent figures count inadequate intake [1].
"People have kind of forgotten this is a risk," said Monica Serrano-Gonzalez, a pediatric endocrinologist affiliated with both Hasbro Children's and the Warren Alpert Medical School at Brown University [14].
What to watch
- A later survey period would show whether the rise since 2001-02 is continuing or has leveled off.
- Goiter or thyroid data from low-iodine regions would test whether the intake shortfall has reached health outcomes.
- The CDC's next population-level reading for women of reproductive age would show whether the group moves past the cusp of mild deficiency.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence62
- Adoption
- Insufficient
- Hype gap−5
- Incentives
- Insufficient
- Confidence55
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
In 2017 and 2018, 24 percent of women and 30 percent of men, aged 14 and older, were not getting an adequate amount of iodine.
- [2]
The 2017-18 shares are about twice as many as in 2001 and 2002, researchers reported in the Journal of Nutrition in 2025.
- [3]
Nearly half of pregnant women have not been getting enough iodine.
- [4]
The study reflects an estimated, short-term look at population iodine levels.
- [5]
The Centers for Disease Control and Prevention stated in its 2026 Nutrition Report that women of reproductive age, at the U.S. population level, are on the cusp of mild iodine deficiency.
- [6]
Companies introduced iodized salt in Michigan in the spring of 1924, and by the fall the Morton Salt Company, a major producer, was selling iodized salt nationwide.
- [7]
By the 1950s, occurrences of goiters had dropped precipitously.
- [8]
Adding iodine to salt was never mandated by the U.S. government.
- [9]
The Michigan State Medical Society recommended the addition of iodine to table salt.
- [10]
An examining physician for the World War I draft reported in 1918 that 30 percent of almost 600 men from a northern Michigan county had goiters, some large enough to be disqualifying.
- [11]
A 1922 Michigan Department of Health study of schoolchildren in four counties revealed that close to 50 percent had goiters.
- [12]
For men born in areas without natural sources of iodine, there was a significant jump in World War II Air Force acceptances, based on a qualifying exam, after widespread salt iodization; the increase did not occur among men born in areas with adequate natural sources, researchers reported in the Journal of the European Economic Association in 2017.
- [13]
"Even mild degrees of iodine deficiency in pregnancy may be associated with measurably lower IQ in children."
- [14]
"People have kind of forgotten this is a risk."
- [15]
If the 2017-18 shares are about twice the 2001-02 shares, the 2001-02 shares were roughly 12 percent of women and 15 percent of men.
- [16]
The comparison covers two survey periods, 2001-02 and 2017-18, so the years between are not reported.
- [17]
If iodine levels in the population continue to trend down, that could eventually result in more goiters and harm brain development in children.
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Sources
1 independent publisher whose own reporting we read for this story.
- sciencenews.orgMany American diets may not include enough of this essential nutrient
1 article · October 15, 2026
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