Iodised salt all but eradicated iodine deficiency years ago, but cases are now rising. Pregnant women and children are especially vulnerable
The 13-year-old boy came to the clinic with a rapidly ballooning neck. Doctors were puzzled.
Testing ruled out their first suspicion. But further tests pinpointed what they - and the boy - had been missing: iodine.
A century ago, iodine deficiency affected children across large swathes of the United States and the rest of the world. It essentially disappeared after some food makers started adding it to table salt, bread and other foods, in one of the great public health success stories of the 20th century.
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But today, people are getting less iodine because of changes in diet and food manufacturing.
Although most people are still getting enough, researchers have increasingly been reporting low levels of iodine in pregnant women and other people, raising concerns about an impact on their newborns.
And there is also a very small, but growing, number of reports of iodine deficiency in children.
"This needs to be on people's radar," says Dr Monica Serrano-Gonzalez, a Brown University doctor who treated the boy in 2021 in Providence, Rhode Island.
Iodine is a trace element found in seawater and in some soils - mostly in coastal areas. A French chemist accidentally discovered it in 1811 when an experiment with seaweed ash created a purple puff of vapour. The name iodine comes from a Greek word meaning violet-coloured.
Later that century, scientists began to understand that people need certain amounts of iodine to regulate their metabolism and stay healthy, and that it is crucial in the development of brain function in children.
One sign of insufficient iodine is a swelling of the neck, known as a goitre. The thyroid gland in the neck uses iodine to produce hormones that regulate the heart rate and other body functions. When there is not enough iodine, the thyroid gland enlarges as it goes into overdrive to make up for the lack of iodine.
At the beginning of the 20th century, goitre was very common in children in certain inland parts of the US, especially in a "goitre belt" that stretched from Appalachia, in the east, and the Great Lakes to the northwest of the country.
Some of the children were unusually short, deaf, intellectually stunted and had other symptoms of a syndrome once known as "cretinism".
Public health experts realised they could not solve the problem by feeding everyone seaweed and seafood, but they learned that iodine can essentially be sprayed on table salt.
Iodised salt first became available in 1924. By the 1950s, more than 70 per cent of American households used iodised table salt. Bread and some other foods were also fortified with iodine, and iodine deficiency became rare.
But diets changed. Processed foods now make up a large part of the Western diet, and though they contain a lot of salt, it is not iodised. Leading bread brands no longer add iodine.
In the case of the 13-year-old boy, he has mild autism and was a fussy eater, mostly only eating specific brands of bread and peanut butter.
For people who do salt their food, the fashion now is to use kosher salt, Himalayan rock salt or other non-iodised products.
"People have forgotten why there's iodine in salt," says Dr Elizabeth Pearce, an endocrinologist and epidemiologist specialising in thyroid disorders at Boston Medical Center, in Massachusetts.
She is a leader in the Iodine Global Network, a non-governmental agency working to eliminate iodine deficiency disorders.
Pearce noted a reported 50 per cent drop in iodine levels in Americans surveyed between the 1970s and the 1990s.
Though iodine consumption is falling overall, most Americans are still getting enough through their diet, experts say. But doctors worry that is not the case for women and children, who are most vulnerable to iodine deficiency.
The American Academy of Pediatrics and other medical societies recommend all pregnant and breastfeeding women get 150 micrograms of iodine each day. You can get that from one-half to three-quarters of a teaspoon of iodised table salt.
In the past 15 years or so, US researchers have increasingly reported seeing mild iodine deficiency in pregnant women.
A Michigan State University study of about 460 pregnant women in the city of Lansing found about a quarter of them were not getting enough.
Many prenatal vitamins do not contain iodine, noted Jean Kerver, the study's lead author. That is why doctors recommend that pregnant or breastfeeding women check labels to ensure they are taking multivitamins or prenatal supplements with iodine.
Some studies have linked even mild iodine deficiency to lower IQs and language delay in children, although there is debate about at exactly what levels problems start, Pearce says.
Experts say there has not been enough research to establish the actual impact of iodine deficiency on the US population in recent years.
Serrano-Gonzalez says she and her colleagues have seen four other cases in children in their clinic in Providence.
"We're concerned this may be increasing, especially in patients with restricted diets," she says.
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2025-01-11T08:26:23Z