Supplement · Minerals
Iodine (kelp)
Also known as: Kelp, Potassium iodide
Essential for thyroid hormones; both too little and too much cause thyroid problems.
- Evidence
- Silver· human data
- Sources cited
- 1
- Last reviewed
- 22 July 2026
Iodine is essential for making thyroid hormones, which set metabolic rate. Deficiency (a real risk without iodised salt, dairy or seafood, and especially important in pregnancy) causes goitre and, in pregnancy, impaired development.
The catch is that the thyroid is sensitive to iodine in both directions: too much, easy to get from concentrated kelp supplements, whose content varies widely, can itself trigger thyroid dysfunction. Meet needs through diet or modest, well-defined doses rather than high-dose kelp.