What happens if you do not get enough iodine?

The thyroid grows larger, which is called a goiter. Goiter is usually the first sign of iodine deficiency.^[1] Below about 10 to 20 µg a day, the thyroid cannot make enough hormone, and hypothyroidism follows.^[1] In pregnancy, severe deficiency can harm the growth and brain of the fetus and can cause miscarriage and stillbirth.^[1] Iodine deficiency is the most common cause of preventable intellectual disability in the world.^[1]

People at higher risk:

• people who do not use iodized salt^[1]
• pregnant women^[1]
• vegans and people who eat little dairy, seafood or eggs^[1]
• people in regions with low-iodine soil, such as mountains and river valleys that flood often^[1]

In a 2-year trial, women on a Paleolithic-type diet, with no dairy and no table salt, had their urine iodine fall from 71 to 36 µg/L within 6 months.^[2]