Iodine

Trace mineral · thyroid

What does Iodine do in your body?

The thyroid builds iodine into thyroid hormones, which set your metabolic rate and are critical for brain development before birth.

What does Iodine do?

Becomes part of T4 and T3 thyroid hormones.

Where does Iodine act in the body?

Thyroid gland; developing brain.

Which foods contain Iodine?

Iodized salt, seaweed, fish, dairy, eggs. Sea salt and specialty salts usually aren't iodized.

How much Iodine do adults need?

RDA: 150 mcg for adults; 220 mcg in pregnancy, 290 mcg while breastfeeding. Upper limit: 1,100 mcg.

What happens with too little Iodine?

Can cause goiter (enlarged thyroid) and hypothyroidism. Deficiency in pregnancy can impair a child's brain development.

Can you get too much Iodine?

Can also cause thyroid problems. Some seaweed supplements contain very high amounts.

What does Iodine interact with?

Selenium is needed to activate thyroid hormone.

What is known and unknown about Iodine?

Iodine deficiency is the world's leading preventable cause of intellectual disability; salt iodization is a major public health success.

Evidence & sources

• Iodine deficiency is one of the world's most common preventable causes of brain damage. Evidence: established. Known: Large global programs of salt iodization have reduced it dramatically. Unknown: — Source: World Health Organization, Iodine deficiency — micronutrient programmes (Current revision).

Connected topics

• Thyroid
• Selenium
• Brain
• Sodium

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.