Iodine
Essential for thyroid hormone synthesis. Most people get enough from salt or seafood, but those who don't are genuinely deficient.
Adequate iodine prevents cretinism, goiter, and hypothyroidism — among the highest-impact public health interventions ever. Supplementing when not deficient provides no benefit; high-dose supplementation in already-replete people can trigger autoimmune thyroid disease (especially Hashimoto's flares).
Make it part of your plan
Reference dose
150 mcg/day RDA for adults. 220 mcg in pregnancy, 290 mcg in lactation. Multivitamins typically deliver 100–200 mcg. High-dose protocols (12–50 mg of Lugol's) are controversial — proceed only under supervision with thyroid monitoring.
Choose a stack first, or enter your own amount here. Reference information is not a personal prescription.
Iodine is the structural atom in thyroid hormones (T3 has three iodines, T4 has four). Without it, the thyroid can't produce hormones, the body slows down, and a goiter develops. Mandatory salt iodisation eliminated severe deficiency across most of the developed world a century ago — but people on low-sodium diets, sea-salt-only diets, plant-based diets without seaweed, and pregnant women in particular can still fall short. Iodine has a narrow therapeutic window: too little causes hypothyroidism, too much can cause hyperthyroidism, autoimmune flares, or thyroid suppression.
- Form
- Potassium iodide (the standard, used in iodised salt and most supplements). Nascent iodine (atomic form, marketed as faster-absorbing — evidence for advantage is weak). Lugol's solution (iodine + potassium iodide combo, traditional clinical form). Kelp / seaweed is variable and can deliver erratic doses — fine as food, less so as a measured supplement.
- Timing
- AM with food. Anytime really.
- Schedule
- Daily.
- Side effects
- Acne (especially at higher doses). Metallic taste. Rarely: thyroid suppression or hyper-stimulation, acneiform rash, mucosal irritation.
- Interactions
- Lithium (additive thyroid suppression). Amiodarone (already iodine-rich). Anti-thyroid drugs (methimazole, PTU) — opposing actions. ACE inhibitors / potassium-sparing diuretics (if taking potassium iodide).
- Contraindications
- Autoimmune thyroid disease (Hashimoto's, Graves') — additional iodine can trigger flares. Always test thyroid antibodies (TPO, TgAb) before high-dose iodine. Active hyperthyroidism. Iodine-induced hyperthyroidism.
- Lab markers
- Urinary iodine (the standard population marker — preferably 24-hour collection). TSH, free T4, free T3 to assess thyroid function. TPO antibodies before high-dose iodine.
- Food sources
- Sea vegetables (kelp, nori, wakame, dulse — extremely high, almost too high). Seafood (cod, shrimp, tuna). Dairy (cows are supplemented or get iodine from feed). Eggs. Iodised salt — the simplest answer for most people. Note: sea salt is NOT a good iodine source unless specifically iodised.
Pairs with
Selenium (required for thyroid hormone conversion T4 → T3 and for protecting the thyroid from iodine-induced oxidative damage — these two should usually travel together). Zinc, iron, tyrosine (other thyroid cofactors).
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