A salt additive that was created to help combat a health risk, has become a regular purchase for many people not only in the United States, but worldwide as well.
While we've been ingesting salt for millennia, adding iodine to table salt is a relatively recent undertaking, and the effects of using iodized salt have been discernible in cutting down on goiter, a condition characterized by a swollen thyroid gland, and other less prevalent problems, such as infertility and even birth defects. Women who are iodine deficient have a harder time getting pregnant
Because the human body does not naturally produce iodine, and the thyroid needs the mineral to function properly, government agencies and scientists before World War I had been seeking a way to add iodine to people's diets. They decided that salt—the stuff that's on nearly everyone's table—was the ideal way to get Americans to ingest iodine.
Introduction of Iodized Salt
The first boxes of iodized salt, made by the Morton Salt Co., appeared on supermarket shelves in Michigan on May 1, 1924. Michigan was one of a number of Midwest states in what was then called "the Goiter Belt." Michiganians didn't exactly embrace the new product, and people in neighboring states that also showed high concentrations of goiter didn't jump on the iodized salt bandwagon either. The federal government rejected an attempt to make iodized salt mandatory, and even today there is no requirement that Americans buy or consume iodized salt. However, the number of goiter cases dropped precipitously after iodized salt became available.
What about iodized sea salt? Most commercial salt is made from rock salt that comes from underground salt mines. But sea salt, which is harvested by evaporating pools of seawater, is an increasingly popular type of salt. Chemically, sea salt and rock salt are the same, and iodine doesn't occur naturally in either one. Some manufacturers add iodine to sea salt, just as they do for ordinary iodized salt. Just check the label to be sure.
A change in Americans' diets has lessened the need to rely on iodized salt for iodine. Eat sushi? There's plenty of iodine in that seaweed wrapper that binds your rice and fish. Speaking of fish, cod, and tuna, even canned tuna, contain plenty of iodine. Shrimp and other seafood also are good sources of the mineral. Cage-free eggs can add iodine to your diet, cutting down the need for iodized salt.
Rest of the World
While Americans have always had a choice of iodized versus regular table salt, the rest of the world seems to have fallen into the iodized salt camp—particularly low and moderate income countries in South America, the former Soviet bloc, and Africa. Not surprisingly, those nations still have large numbers of people who suffer from goiter.
Italy and Spain have laws on the books that require iodized salt, but enforcement is lax.