Iodine
An essential trace mineral added in tiny amounts (often as potassium iodide or iodate) to help the thyroid make hormones; sometimes present naturally from seaweed or dairy ingredients.
Should I eat Iodine?
Iodine is essential and safe at the tiny amounts used in iodized salt and fortified foods. Get enough, but avoid chronic high intakes—especially from seaweed or supplements—if you want to protect thyroid health.
Summary
Iodine supports thyroid hormones that regulate metabolism and development, and most adults need about 150 mcg/day. Authorities worldwide back iodized salt using potassium iodide or iodate to prevent deficiency, and U.S. rules require non‑iodized salt to disclose it does not supply iodide. The main caution is excess: the U.S. upper limit is 1,100 mcg/day (EU 600 mcg/day), and some seaweeds can far exceed this. Infants and people with thyroid disease are more sensitive to sudden changes in intake. At typical fortification levels, benefits clearly outweigh risks for most people.
Key Research Points
Small daily need with clear upper limit
Adults need about 150 micrograms (mcg) per day, while the safe upper limit is 1,100 mcg/day in the U.S. and 600 mcg/day in the EU—so aim for enough, but not too much.
Iodized salt is effective and regulated
Global and U.S. authorities endorse potassium iodide or iodate in table salt to prevent deficiency, and non‑iodized salt must state it does not supply iodide.
Too much can disrupt thyroid function
Long-term high intakes—often from seaweed with very high iodine or from supplements—can trigger hypo- or hyperthyroidism, especially in sensitive people.
Overview
What is it?
Why is it used?
Origin
Public health programs in the early 1900s showed that adding iodine to table salt prevents goiter. Since then, many countries have adopted salt iodization so everyday foods provide small, steady iodine. Natural iodine also appears in seaweed and in animal foods like milk and eggs—often because livestock feed contains iodine.
Process: Fortify salt or food with potassium iodide/iodate
Steps
Chemicals
Research & Safety
Potential Concerns
The biggest risk is too much iodine over time, which can disrupt thyroid function. This is most likely from frequent use of high‑iodine seaweed (like kelp) or from high‑dose supplements rather than from iodized salt. The iodine used in foods is a refined compound (potassium iodide or iodate) added to refined salt; this processing itself is not a health hazard, and safety concerns center on dose, not the additive form. If you have a thyroid disorder, any large change in iodine intake should be discussed with your clinician.
Potential Benefits
Your thyroid needs iodine to make hormones that guide metabolism, growth, and brain development. Adults generally need about 150 mcg/day; pregnancy (220 mcg/day) and lactation (290 mcg/day) require more. Iodized salt and fortified foods provide reliable, tiny amounts that help prevent goiter and other deficiency problems. This strategy has strong support from public health agencies because it works with minimal change to taste or calories.
Digestive Effects
At the very small amounts used to iodize salt, iodine does not typically cause digestive symptoms. Most health effects of too much iodine show up in the thyroid rather than the gut. Large, sudden intakes from supplements or concentrated seaweed can be poorly tolerated in some people, so reduce intake if you notice symptoms and seek advice if needed. For most people, regular use of iodized salt does not cause stomach issues.
Limit Consumption
Pregnancy and lactation have higher iodine needs to support fetal and infant brain development; meet needs but avoid high‑dose supplements unless advised by a clinician. Infants require only 110–130 mcg/day, and their smaller size makes them more sensitive to excess—avoid concentrated seaweed or drops unless prescribed. People with thyroid disease (e.g., autoimmune thyroiditis, nodular goiter) may react to abrupt increases in iodine and should seek individualized guidance. Respect upper limits (U.S. 1,100 mcg/day; EU 600 mcg/day) to minimize risk.
Fact Sheet
Regulatory Status
ESG & Sustainability
Allergens and Diet
Natural Alternatives
Dulse flakes
Kelp powder
Nori
Citations
Iodine — Health Professional Fact Sheet
2024-11-05NIH ODS • NIH Office of Dietary Supplements
Scientific Opinion on Dietary Reference Values for iodine
2014-05-07EFSA NDA Panel • EFSA Journal
21 CFR §100.155 — Salt and iodized salt
2025-01-01FDA • eCFR (FDA)
21 CFR §184.1634 — Potassium iodide
2025-01-01FDA • eCFR (FDA)
21 CFR §184.1635 — Potassium iodate
2025-01-01FDA • eCFR (FDA)
Iodization of salt for the prevention and control of iodine deficiency disorders
2023-08-09World Health Organization • WHO
USDA, FDA, and ODS-NIH Database for the Iodine Content of Common Foods — Documentation
2024-11-01USDA ARS et al. • USDA ARS / FDA / NIH ODS
Potassium Iodate (INS 917) — JECFA/Codex entry
2025-01-01FAO/JECFA • FAO/JECFA
Salt & Preservatives in Organic Products — FAQ
2016-01-01USDA Agricultural Marketing Service • USDA AMS
Consequences of acute and long-term excessive iodine intake
2024-06-01Blikra MJ et al. • Critical Reviews in Food Science and Nutrition