Doctors warn that iodine deficiency – a dietary problem from the past – is making a comeback

A 13-year-old boy came to the clinic with a rapidly ballooning neck. The doctors were puzzled.

Testing ruled out their first suspicion. But further tests revealed what they – and the boy – were missing: iodine.

A century ago, iodine deficiency affected children in large parts of the country. It essentially disappeared after some food manufacturers began adding it to table salt, bread and some other foods, in one of the great public health success stories of the 20th century.

But today, people are getting less iodine because of changes in diet and food production.

Although most people are still getting enough, researchers have increasingly reported low levels of iodine in pregnant women and other people, raising concerns about the impact on their newborns. And there are also a very small but growing number of reports of iodine deficiency in children.

“This should be on people’s radar,” said Dr. Monica Serrano-Gonzalez, a Brown University doctor who treated the boy in 2021 in Providence, Rhode Island.

What is iodine?

Iodine is a trace element found in seawater and some soils – mainly in coastal areas. A French chemist discovered it by accident in 1811, when an experiment with seaweed ash created a purple puff of steam. The name iodine comes from a Greek word meaning purple.

Later that century, scientists began to understand that humans need certain amounts of iodine to regulate their metabolism and stay healthy, and that it is essential in developing brain function in children.

A sign of insufficient iodine is a swelling of the neck, known as a goiter. The thyroid gland in the neck uses iodine to produce hormones that regulate heart rate and other body functions. When there is not enough iodine, the thyroid gland enlarges as it goes into overdrive to compensate for the lack of iodine.

In the early 20th century, goiter was very common in children in certain parts of the interior of the United States, especially in the “goiter belt” that stretched from Appalachia and the Great Lakes in the northwestern United States. Some of the children were extremely short, deaf, intellectually challenged and had other symptoms of a syndrome once known as “cretinism”.

Adding iodine to salt

Public health experts realized they couldn’t solve the problem by feeding everyone seaweed and seafood, but they learned that iodine can essentially be sprinkled on table salt. Iodized salt first became available in 1924. By the 1950s, more than 70% of American households used iodized 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 American diet, and although they contain a lot of salt, it is not iodized. Major 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 eating only specific brands of bread and peanut butter.

And for people who salt their food, the trend now is to use kosher salt, Himalayan rock salt, or other non-iodized products.

“People have forgotten why there is iodine in salt,” said Dr. Elizabeth Pearce of Boston Medical Center. She is a leader in the Global Iodine Network, a non-governmental agency working to eliminate iodine deficiency disorders.

She noted a reported 50% drop in US iodine levels among Americans surveyed between the 1970s and 1990s.

How much iodine is enough?

Although iodine consumption is declining overall, most Americans are still getting enough in their diets, experts say. But doctors worry that is not the case for women and children, who are most at risk of iodine deficiency.

The American Academy of Pediatrics and other medical societies recommend that all pregnant and breastfeeding women get 150 micrograms of iodine daily. You can take it from one and a half to three quarters of a teaspoon of iodized table salt.

In the last 15 years or so, American 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 that about a quarter of them weren’t getting enough.

Many prenatal vitamins do not contain iodine, noted Jean Kerver, lead author of the study. That’s why doctors recommend that pregnant or nursing women check labels to make sure they’re taking multivitamins or prenatal iodine supplements.

Some studies have also linked mild iodine deficiency to lower IQs and language delays in children, although there is debate about what levels the problems start, Pearce said.

Experts say there hasn’t been enough research to determine what impact iodine deficiency has actually had on the American population in recent years.

Serrano-Gonzalez said she and her colleagues have seen four other cases in children at their clinic in Providence.

“We are concerned that this may be increasing, particularly in patients with restricted diets,” she said.