Salt isn’t just a seasoning anymore, and the popularity of Salt Bae ― the hunky chef who salts his food with bravado ― is proof of that.

Then there’s Himalayan pink salt, flaky sea salt and kosher salt that remind us we’re in a new era of cooking. But despite the plethora of gourmet salt options on the market, many households will still carry and use regular old table salt, which in many parts of the world is iodized. But why is our common table salt iodized, anyway?

Salt is iodized in large part to prevent goiter. A goiter is an enlarged thyroid, and one of the causes is iodine deficiency (the thyroid enlarges to try to get more iodine). According to the National Institutes of Health, Goiter had become endemic in the 1920s in certain regions of the United States ― the Great Lakes, Appalachians and Northwestern regions were nicknamed the goiter belt because of this. As a solution to introduce more iodine into the diets of people who lived inland or at high elevations, where iodine is not naturally present, the United States started fortifying salt with iodine. The goiter problem was gone almost overnight.

Iodine deficiency can lead to more than just goiter. According to the National Bureau of Economic Research, iodine deficiency is the leading cause of preventable mental retardation in the world today. In fact, it was found that iodization actually raises IQ levels.