The problem was widespread. Many people — including those who lived in the American Midwest — were suffering from goiter, a thyroid condition that had been linked to iodine deficiency at the end of the 19th century. The solution turned out to be incredibly simple, universally effective and really cheap: Putting iodine in table salt. After researchers determined that iodized salt was the answer, it was first introduced as a commercially available food item in Michigan in 1924.
The Salt Institute estimates that nearly 70 percent of the table salt sold today in the United States is iodized. But there are many parts of the world where iodine in the food supply is lacking. As recently as 1990, only 20 percent of the world’s households had access to iodized salt. UNICEF has called iodine deficiency the single greatest cause of cognitive deficits in the world, with 25 percent of the world’s population still at risk in 2013.
Health officials across the globe have worked to get iodized salt to the regions where deficiency is most common, especially Southeast Asia and Africa, where 58 million people had inadequate iodine intake in 2011. Progress has been made. From 2003 to 2011, the number of iodine-deficient countries fell from 54 to 32.