From: National Institutes of Health: Iodine

Iodine is an essential component of thyroid hormones.

We need about 150 micrograms a day.

If a person’s iodine intake falls below approximately 10–20 mcg/day, hypothyroidism occurs, a condition that is frequently accompanied by goiter.

Source: Registered Dental Hygienist (RDH) Magazine

Mild-to-moderate iodine deficiency can cause goiter as well as impaired mental function and work productivity secondary to hypothyroidism.

Groups at Risk of Iodine Inadequacy

• • People who do not use iodized salt
  • Pregnant women. The RDA for iodine increases during pregnancy.
  • Vegans. Seafood is one of the best natural sources for iodine (that includes seaweed but most people in the US don’t eat it). Eggs contain iodine because it’s added to chicken feed so free range eggs are iffy. Dairy products contain iodine because it’s used as a disinfectant on udders and machines. (What else is in there?)

Soil contains varying amounts of iodine which impacts the iodine content of crops. Most fruits and vegetables are poor sources of iodine. (Their table lists essentially zero iodine in broccoli, banana, lima beans, green peas, pasta, brown rice, and corn). Iodine content of meat and animal products varies depending on what animals are fed.

Iodized salt in the US contains 45 mcg iodine per gram of salt (between 1/8 and 1/4 teaspoon). Not all salt is iodized: