Lodized Salt

According to the National Institutes of Health’s Office of Dietary Supplements, tests have shown that the population in the United States is “iodine sufficient.” Most Americans who eat a varied diet get enough iodine even if they don’t use iodized salt. They are at little risk of iodine deficiency, which can lead to goiters (swollen thyroid glands in the neck) and dwarfism and is a leading cause of mental impairment worldwide.

However, some pregnant women are at risk of low iodine levels, which potentially endanger their babies. The need for iodine increases during pregnancy, and women who do not eat dairy products or do not take the vitamin supplements that doctors typically prescribe are at risk.

Other than iodized salt, sources of iodine include fish, dairy products, grains (including bread) and fruits and vegetables. Fish get it from the ocean floor and seaweed, and plants get it from growing in soil with iodine in it. That’s why it is present in the grass that cows eat, which then shows up in cow’s milk and dairy foods.

Iodine is also added to some cow feeds, and it is used in disinfectants used to wash cow udders before milking, so some of that iodine then washes into the milk (disinfectants are used in low concentrations and generally considered harmless).

Some children in Japan have thyroid problems from getting too much iodine rather than too littl

The situation in Europe echoes that of the United States but is more varied. No European country has severe iodine deficiency, but some have subpopulations — especially pregnant women — with levels low enough to be considered unhealthy. Iodized salt is common in some countries but not in others. In Switzerland, for example, 80 percent of households use it, while in Britain only 5 percent of households do, and in 2011, it was reported that Britain could face widespread iodine deficiency, especially among teenage girls who rarely drank milk or ate fish.

Before the modern era allowed food to be transported long distances, mountainous countries and countries situated in flood plains typically had chronic iodine deficiency because melting snowpack and floodwaters tend to wash iodine out of the soil and local plants and animals had little iodine. Even Switzerland, like Bolivia, Nepal and other mountainous countries, once had high rates of goiters and cretinism caused by iodine deficiency, as did low-lying flood-prone areas far from the ocean in Eastern Europe and Southeast Asia.