Health · Evidence Strong
Iodine (from Kelp)
An essential trace element — deficiency and excess both cause thyroid problems.
Dosage
About 150 mcg/day for healthy adults (RDA); no more without medical guidance
Timing
Daily
Evidence
Strong
Overview
Most people using iodized salt or eating seafood do not need iodine supplements. Very high-dose kelp products can push intake far above safe levels and destabilize thyroid function.
Benefits
- →Supports normal thyroid function when intake is deficient
Best for
Stacks with
Side effects
- • Excess intake can cause thyroid dysfunction and worsen certain thyroid conditions
Warnings & cautions
- ⚠Do not exceed 1,100 mcg/day (tolerable upper limit for adults).
- ⚠Kelp-based supplements can contain highly variable and sometimes very high iodine doses — read labels carefully.
- ⚠People with autoimmune thyroid disease (Hashimoto's, Graves') should not supplement iodine without medical guidance.
- ⚠Discuss with a physician if pregnant, breastfeeding, or on thyroid medication.
Drug & condition interactions
- • May interact with thyroid medications, lithium, and certain diuretics.
Evidence notes
Iodine is essential for thyroid hormone production. Requirements are small and both deficiency and excess cause thyroid dysfunction.
Research references
- [1] Zimmermann MB, Boelaert K. Iodine deficiency and thyroid disorders. — Lancet Diabetes Endocrinol, 2015; 3:286–295
Medical disclaimer
This page is for general educational purposes only and is not medical advice. Individual response to supplements varies. Consult a licensed healthcare provider before starting any supplement — especially if you are pregnant, breastfeeding, under 18, taking prescription medication, or managing a medical condition.
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