Iodine supplements: needs, sources and safety

Iodine is essential for making thyroid hormones, but a supplement is not automatically needed. The decision depends on diet, the chosen form and thyroid context.

Iodine is an essential component of thyroid hormones. These hormones support many biochemical processes and the development of the nervous system and skeleton before birth and in early life.

Adults need 150 mcg per day; needs rise to 220 mcg in pregnancy and 290 mcg during breastfeeding. These are total-intake reference values, not universal supplement doses. Fish, seafood, dairy products and eggs can provide iodine. Iodized salt can contribute, but not every sea, pink or fleur de sel is iodized: check the label.

Supplements commonly contain potassium iodide or sodium iodide. Kelp and other seaweed products can vary in iodine content, so “natural” does not mean predictable.

Regular excessive intake can disrupt thyroid function. Be especially cautious with known thyroid disease, pregnancy, breastfeeding, regular medicines or several iodine-containing products.

Check food sources first; add up iodine from multivitamins and seaweed; prefer a clearly labelled amount; ask a professional before use in pregnancy, breastfeeding, thyroid disease or regular treatment. See also the selenium article and the vitamin D article.

1. 01NIH Office of Dietary Supplements, 2024 — https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
2. 02NIH Office of Dietary Supplements, 2024 — https://ods.od.nih.gov/factsheets/Iodine-Consumer/
3. 03ANSES, 2022 — https://www.anses.fr/fr/content/iode
4. 04NHS, 2020 — https://www.nhs.uk/conditions/vitamins-and-minerals/iodine/
5. 05PubMed review, 2014 — https://pubmed.ncbi.nlm.nih.gov/24342882/