Give Now

A Moment of Science

Why Does Table Salt Contain Iodide?

Sodium chloride is a basic cooking ingredient. However, have you ever stopped and wondered what was in "iodized" salt?

Morton iodized salt

Photo: canardo (flickr)

Iodized salt is a very common cooking ingredient.

Pure, ordinary salt is simple. The scientific name for it is sodium chloride.

But the label on a salt box shows that table salt usually contains more than just sodium chloride.

What Does “Iodized” Mean?

Table salt often comes in “iodized” form — which means it includes a small amount of potassium iodide or sodium iodide. Iodized salt is intended to supply us with the trace amount we need of the chemical element iodine, which is necessary for the proper functioning of our thyroid gland.

An iodine-deficient diet leads to enlargement of the thyroid gland, a condition called goiter. Severe iodine deficiency during pregnancy is also dangerous to the child.

Living Near The Sea Had Benefits

Before iodized salt became available, people living near seacoasts got adequate iodine because seawater and coastal soil contain iodine compounds. On the other hand, people living inland or in mountainous country tended to have iodine-deficient diets and a high incidence of goiter.

After public-health investigators realized the connection between iodine deficiency and goiter, they looked for ways to insure that people living inland got the iodine they needed. The first iodized table salt was sold in Michigan in 1924.

Keep It Stable

Iodized salt needs another additive, a stabilizer, to keep the potassium iodide from breaking down and releasing iodine into the air in the salt box, giving the salt a chlorine-like odor. The type of sugar known as dextrose will do the job, and is often used as an iodide stabilizer.

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science