As wellness trends take off, iodine deficiency is quietly making a comeback

A a century ago, Much of North America was known as the Goiter Belt. In some areas, between 26% and 70% of school-age children had characteristic swellings in the neck, or goiter, caused by an enlarged thyroid gland. After experiments showed that iodine supplements could prevent goiter, iodized salt was introduced commercially in 1924, starting in grocery stores in Michigan. By the 1940s, the goiter belt had disappeared.