Potassium iodide
A mineral salt used in tiny amounts to supply iodine, mainly via iodized table salt.
Should I eat Potassium iodide?
At regulated amounts, potassium iodide in iodized salt is an effective, safe way to prevent iodine deficiency. The main watch‑out is avoiding excess from multiple sources if you have thyroid concerns.
Summary
KI is a purified mineral salt used in micro‑doses to supply essential iodine, chiefly via iodized table salt. U.S. regulations set clear limits and require labeling so consumers know when salt supplies iodide, while international bodies define upper intake levels to protect thyroid health. Stability and policy differ by region (with iodate often preferred in humid climates), but the goal is consistent iodine without overexposure. Most healthy people tolerate iodized salt well; those with thyroid disease or on thyroid medication should personalize intake with medical guidance.
Key Research Points
Too much iodine can impair thyroid function
Total iodine above established upper limits can trigger hypo- or hyperthyroidism in some people; adult upper limits range from 600 µg/day (EU) to about 1,000–1,100 µg/day across major authorities.
Some people are more sensitive
People with autoimmune thyroid disease, nodular goiter, or those taking thyroid medicines can react to changes in iodine intake and should personalize targets with a clinician.
Formulation rules and carrier choice matter
FDA caps added iodine from KI in fortified foods (e.g., 225 µg/day for adults 4+) and requires clear labeling of iodized salt; WHO favors iodate over iodide in humid climates due to better stability, and EU countries vary in which carrier is allowed.
Overview
What is it?
Why is it used?
Origin
Iodine deficiency and goiter were common in parts of the world in the early 20th century. In the United States, manufacturers began adding iodine—often as potassium iodide—to table salt in the 1920s as a simple, population-wide fix. Today, countries use iodide or iodate depending on climate and salt quality, and labels typically call it out as “iodized salt.”
Process: React, crystallize, wash, and dry
Steps
Chemicals
Research & Safety
Potential Concerns
The main risk is too much iodine from combined sources (iodized salt, supplements, seaweed, and fortified foods), which can disrupt thyroid function in susceptible people. Adults should aim to stay below established upper limits; the FDA also limits the amount of added iodine permitted from fortified foods per day. KI is a highly refined mineral salt, but at micro‑doses the concern is dose, not processing byproducts, and it is not hydrogenated. Stability varies by iodine carrier and climate (iodate is often preferred in humidity), which can affect how much iodine a product actually delivers. People with known thyroid disorders or on thyroid medication should discuss appropriate intake with a clinician.
Potential Benefits
KI provides reliable iodine to support thyroid hormone production, which governs metabolism, growth, and brain development. Adding about 0.01% KI to table salt has been a cornerstone public‑health strategy to reduce deficiency. U.S. regulations and labeling help consumers recognize when a salt supplies iodide. When total iodine intake stays within recommended limits, KI fortification is an efficient way to meet daily needs.
Digestive Effects
At the tiny levels used in iodized salt, digestive side effects are uncommon. Most tolerability issues arise with higher‑dose supplements, not typical dietary exposure. If sensitive, some individuals may notice a transient metallic taste from iodine, but this is unlikely at standard iodized‑salt levels. Overall, concerns center on thyroid effects from total iodine exposure rather than gastrointestinal irritation.
Limit Consumption
Pregnant and lactating people need more iodine for fetal and infant brain development but still should stay under upper limits; U.S. rules cap added iodine from fortified foods at 300 µg/day in these groups. Infants and young children have lower safe ceilings; for fortified foods, FDA sets age‑specific limits (e.g., 45 µg/day for infants). Adults and children 4+ are capped at 225 µg/day from KI‑fortified foods, separate from total daily iodine from all sources. Individuals with autoimmune thyroid disease, nodular goiter, or on thyroid medications may be more sensitive to iodine shifts and should individualize targets with their clinician.
Fact Sheet
Regulatory Status
ESG & Sustainability
Allergens and Diet
Natural Alternatives
Dairy/eggs (dietary sources)
Iodized seaweed flakes
Iodized salt (potassium iodate)
Citations
21 CFR 100.155 — Salt and iodized salt
2024-01-01FDA • eCFR (FDA)
21 CFR 184.1634 — Potassium iodide
2024-01-01FDA • Cornell LII
21 CFR 172.375 — Potassium iodide
2024-01-01FDA • Cornell LII
Iodine — Health Professional Fact Sheet
2024-11-05ODS Staff • NIH Office of Dietary Supplements
Scientific Opinion on Dietary Reference Values for iodine
2014-05-07EFSA NDA Panel • EFSA Journal
Iodine — JECFA evaluation summary
2020-01-01WHO/JECFA • WHO/JECFA database
2024 Full Scope Technical Report — Potassium Iodide (Handling)
2024-04-17USDA AMS • USDA AMS
FDA regulations regarding iodine addition to foods and labeling of foods containing added iodine
2016-08-18Trumbo PR • American Journal of Clinical Nutrition (review hosted on PMC)
Universal salt iodisation — member-state practices on iodide/iodate
2006-01-01EC services • European Commission (Food Safety)