Potassium Iodide
Also known as: KI, iodine (as potassium iodide), potassium iodide USP
The standard iodine source in multivitamins, prenatals, and thyroid-support formulas, about 76.5% iodine by weight and absorbed almost completely. It provides a precise, stable dose, which is why it is preferred over kelp when accuracy matters. Most products supply 150 mcg iodine, the adult RDA, with 220–290 mcg in prenatal and lactation formulas. The adult UL of 1,100 mcg is easy to exceed with iodine-only products, so the dose ceiling matters.
Research summary
Supplies iodide, which the thyroid takes up through the sodium-iodide symporter to synthesize thyroxine (T4) and triiodothyronine (T3).
Dosage
Daily amounts, elemental (77% of the compound is the element).
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 75 mcg | 150–300 mcg | 1,100 mcg | 1,100 mcg |
NIH ODS — UL of 1,100 mcg/day for adults from all sources
Doses are micrograms of elemental iodine. Potassium iodide (MW 166.0) is 76.5% I: 126.9 ÷ 166.0. Because iodine doses are in micrograms, the ingredient is commonly supplied as a 1% trituration (10,000 mcg/g), and raw_material_mg_per_dose_unit = 0.1 mg per mcg reflects that — adjust to the supplier's premix. Adult RDA 150 mcg; pregnancy 220 mcg; lactation 290 mcg. Some studies reviewed by ODS used 1,500–6,000 mcg/day, above the UL; the app caps at 1,100 mcg. Take with food.
Source material: synthetic (iodine reacted with potassium hydroxide), usually supplied as a 1% dilution
As supplied: Typically supplied as a 1% (10,000 mcg/g) trituration; pure KI ≈ 76.5% I
Forms of Iodine
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Potassium Iodide | 150–300 mcg | 77% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Kelp (Iodine) | 150–300 mcg | 1% | Capsule, Powder, Tablet | low |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Micro-dose; carrier dilution sets fill weight. Potassium iodide is light-sensitive and can oxidize to free iodine (yellowing) in acidic or moist formulas; stabilized grades or opaque packaging help.
Formulation notes
Iodine interacts with antithyroid drugs, lithium, and ACE inhibitors, and excess intake can disturb thyroid function in people with autoimmune thyroid disease; keep doses near the RDA in general products. Selenium is a common pairing in thyroid formulas. Count iodine from kelp, other seaweeds, and iodized-salt ingredients toward the total.
- Has an upper limit
- Notable drug interactions
Sources
Related ingredients
Iron Bisglycinate
MineralFerrous iron chelated with two glycine molecules, the form most prenatal and gentle-iron products now use.
Typical: 18–30 mg
Iron (Ferrous Sulfate)
MineralThe reference iron salt used in most clinical research and public-health programs, inexpensive and reliably absorbed.
Typical: 18–45 mg
Iron (Ferrous Fumarate)
MineralA ferrous salt of fumaric acid that carries about 33% elemental iron, the highest of the common iron forms, which keeps tablets small.
Typical: 18–45 mg
Vitamin B6 (Pyridoxine HCl)
VitaminPyridoxine hydrochloride is the standard, inexpensive, and highly stable form of vitamin B6 used in nearly all multivitamins and B-complex products.
Typical: 1.7–50 mg
Kelp (Iodine)
MineralBrown seaweed, usually Laminaria or Ascophyllum species, used as a whole-food iodine source in thyroid and multimineral formulas.
Typical: 150–300 mcg