Iodine
Iodine (I)
Minerals. Modern nutrition.
Also called Potassium iodide, Potassium iodate, Lugol's solution, Iodide
Pinyin: diǎn
Spanish: Yodo
Can upset thyroid functionA trace mineral the thyroid gland needs to make thyroid hormones that control metabolism, growth and brain development.
Did you know? In the 1920s, several US states began adding iodine to table salt to stop goiter, a swollen thyroid gland. Iodized salt has greatly reduced goiter in many countries.
What it may help, and how strong the proof is
- Thyroid. Iodine is needed to make thyroid hormone. Iodine deficiency causes goiter and low thyroid function, and iodized salt or iodine pills correct it. Extra iodine does not help people who already get enough.Strong proof
- Cleansing & detox. Iodine is sold for detox and for breast and cancer claims. Good human trials have not shown these work, and high doses can harm the thyroid.Not supported
Parts of the body
Traditional use
Chinese herbal medicine has used sea kelp for goiter for centuries, and seaweed remains a traditional iodine food in East Asia.
How it is classified
- Herbal actions
- Nutritive, Hormone balancer. Energy: neutral.
How people take it
Adults need 150 mcg a day (RDA). Pregnant women need 220 mcg a day, and breastfeeding women need 290 mcg a day. The upper limit is 1,100 mcg a day from food and pills. Iodized salt is the easiest way to get enough.
Food, tablet and topical.
Where to get it
Good sources are iodized salt, cod, tuna and shrimp, milk and yogurt, eggs, and seaweed such as kelp, nori and wakame. Seaweed can contain very large and unpredictable amounts. Pills come as potassium iodide or potassium iodate, and Lugol's solution is a strong iodine liquid.
Be careful
Iodine from food is safe. High doses can upset the thyroid, causing too much or too little thyroid hormone, or swelling of the gland. Strong iodine liquids can burn the mouth and stomach, and kelp supplements can contain very large amounts.
Avoid if: thyroid disease; Graves' disease; iodine allergy.
Mixing with other things
- Use cautionThyroid medicine (levothyroxine (Synthroid))
Extra iodine can worsen an overactive or underactive thyroid and can change the dose of thyroid medicine needed.
- Worth knowing
Iodine and selenium both support thyroid hormone production, and both are needed in balance.
Adds up with others that carry iodine: , , , , , .
The honest take
Iodine is essential for thyroid hormone, and iodized salt prevents goiter in most places. Too much iodine can harm the thyroid, especially from kelp or strong liquids. Claims that iodine detoxes the body or helps breast problems are not supported by good evidence.