Our fancy salt obsession is harming our health

When I was in college, I had a biology professor who was obsessed with iodine and whose life’s work was fighting global dietary deficiencies. He urged us to always use iodized salt, telling us that it had increased the IQs of entire nations and was one of the greatest public health inventions of all time. I still hear his voice in my head every time I’m in the salt section of the supermarket.

In recent years, however, I have had increasing difficulty finding iodized salt on the shelves. Over time it was replaced by Cornish sea salt crystals, pink Himalayan rock salt, smoked salt flakes and kosher salt. The few remaining containers of iodized salt come in dull packaging and appear profoundly cold. This makes me wonder: are we about to undo all the benefits derived from this unassuming food additive?

Iodine is an essential dietary mineral that the thyroid gland uses to make key hormones that regulate metabolism, growth, digestion, heart rate and body temperature.

Adequate iodine intake is especially important during pregnancy because thyroid hormones regulate fetal brain growth. Even mild to moderate impairments in utero are estimated to reduce intelligence by 0.3 to 13 IQ points. Iodine is also important during childhood to support brain development and thyroid function. Case reports have described extremely picky eaters, small for their age, who have difficulty in school and are constantly tired due to iodine deficiency. In children and adults, iodine deficiency can also lead to goiter – a swelling of the neck that occurs when the thyroid gland enlarges in an attempt to take in more iodine.

Foods naturally rich in iodine include seaweed and seafood. Cow’s milk also contains iodine because it is often added to livestock feed, and iodine-based disinfectants are used to clean the teats and milking equipment of dairy cows. Fruits, vegetables, and grains can absorb a small amount of iodine from the soil, but soil iodine levels vary widely. Switzerland and Michigan, once part of the “goiter belt” of North America, both have soils that are very low in iodine. Historically, they had high rates of goiter, reaching up to 70 percent of children in some Swiss cities.

In 1922, Switzerland was the first country to introduce iodized salt, made by adding a small amount of iodine to regular table salt. In a short time, the goiter virtually disappeared, the children grew older, and they received an “IQ injection,” as economist Dimitra Politi described it. This meant that more and more young people were finishing high school and earning college degrees.

In 1924, Michigan also made iodized salt available, soon followed by other parts of the United States and many other countries. Its introduction has been considered one of the factors behind the global increase in IQ observed during the 20th century. Rarely has such an inexpensive invention brought such extraordinary benefits. “For 5 cents per person per year, you can make the entire population smarter than before,” said the late endocrinologist Gerald Burrow. THE New York Times in 2006.

However, now that goiter has long been forgotten, iodized salt is experiencing a crisis of popularity. On the one hand, it can’t compete with the beauty of pink Himalayan flakes. Some of the trendy non-iodized salts specifically advertise their lack of iodized additives, implying that they might be bad for your health. I know parents who deliberately avoid giving their children iodized salt for fear of chemical additives (even though iodine is a natural substance).

While people are using less iodized salt in home cooking, we are also consuming more processed and takeout foods, which are typically prepared with non-iodized salt to avoid adverse reactions during processing. More and more people are becoming vegan or switching from cow’s milk to plant-based milk, further reducing their iodine intake.

As a result of these trends, a study released in November found that the proportion of Americans who do not consume enough iodine has doubled since 2001. Even more worrying, the study found that 46 percent of pregnant women now have insufficient intake.

The story is similar in the United Kingdom. The average iodine level measured in women of childbearing age is “now significantly below the adequacy threshold,” according to a study published in January. And in Australia, 62 percent of pregnant and breastfeeding women have insufficient iodine levels. (Although it should be noted that some places, such as parts of Japan, have the opposite problem of excessive iodine consumption, which comes with its own thyroid problems).

This has led public health experts to urge people in the US, UK and Australia to switch back to iodized salt, to avoid damage to cognitive and thyroid health and the re-emergence of goiter.

Truly, it’s a strange time. The supplement industry is booming, and people are stocking up on zinc, selenium, and ginkgo biloba pills to improve their brain health, even though there is little evidence to support their benefits. In contrast, iodine supplements and salts are neglected, while many people suffer from legitimate iodine deficiencies that carry real risks. I can’t understand this.

But fashionable or not, I’m going to continue searching the supermarket shelves for iodized salt, still too afraid of what my former lecturer would think if I went for the pretty pink flakes.