Thyroid essential. Simple iodine delivery. It dissolves into potassium and iodide, and the iodide is what your thyroid pulls in to build its hormones. Those hormones set your metabolic rate across the whole body.
Reviewed March 2026
Public health figures for this ingredient, reported by the agencies that publish them, cited and dated.
US pregnant women, median 129 micrograms per litre
Across 2005 to 2010, US pregnant women had a median urinary iodine concentration of 129 micrograms per litre, which is below the range considered adequate during pregnancy.
Caldwell et al. (CDC Division of Laboratory Sciences), Thyroid 2013, NHANES 2005 to 2010; median urinary iodine 129 micrograms per litre in pregnant women, less than adequate. ↗Population figures from public health data. Context for the category, not a statement about any individual and not a claim about this product.
Source: NIH ODS + Zimmermann 2009 review
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
Based on 35 human trials with 75% consistency.
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Selenium-dependent deiodinases activate thyroid hormone and selenium peroxidases clear the peroxide produced during iodination, so selenium completes what iodide starts.
Iodide has to be oxidised by the heme enzyme thyroid peroxidase before it can attach to tyrosine, so iron status gates that step.
Thyroid hormone is made by adding iodine atoms to tyrosine on thyroglobulin, so tyrosine is the other half of the molecule.
Iodide supplies the halogen and tyrosine the ring it is attached to, making the pair the substrate side of thyroid hormone synthesis.
Zinc supports both the thyroid hormone receptor structure and deiodinase activity, working downstream of iodide supply.
Retinoid receptors heterodimerise with thyroid hormone receptors and retinoid status modulates TSH, so vitamin A affects the response to thyroid hormone.
Bladderwrack carries its own iodine at concentrations that vary by harvest, so stacking it on a measured potassium iodide dose makes total intake uncertain.
Both forms deliver iodide through the same sodium-iodide symporter, so the doses add together rather than serving different roles.
Thiocyanate from glucosinolate breakdown competes with iodide at the sodium-iodide symporter, reducing how much iodide enters the gland.
Salt is the conventional vehicle for population iodine intake, so salt intake and a potassium iodide dose contribute to the same total.
Thiocyanate, formed from brassica glucosinolates, is a monovalent anion of similar size to iodide and is transported by the same sodium-iodide symporter. High thiocyanate exposure therefore reduces iodide uptake, and the effect is most relevant when iodide supply is already low. This is settled transport pharmacology, and it is a reason to keep iodide intake adequate rather than a reason to avoid brassicas.
Concentrated brassica preparations carry glucosinolate breakdown products, and the thiocyanate among them competes with iodide for the sodium-iodide symporter. A purified indole such as DIM carries less of that load than a whole-plant extract, but the source material is the same. Formulators pairing concentrated brassica actives with iodide should account for the competition.
Phenylalanine hydroxylase converts phenylalanine to tyrosine, and thyroid peroxidase incorporates oxidised iodide onto tyrosyl residues within thyroglobulin. Iodide supply and tyrosine supply are therefore the two substrate inputs to the same reaction. This is precursor biochemistry, not a claim that extra phenylalanine changes anything in a well-fed person.
Iodide oxidises to elemental iodine on exposure to air, light and moisture, which is how iodised salt loses potency in storage. A reducing agent in the same matrix slows that conversion. The benefit is to the product on the shelf and should not be read as an absorption claim.
Activated charcoal binds a wide range of luminal species without distinguishing a mineral from anything else. Taken at the same time as an iodide dose it can reduce what is available for absorption. Separating doses by several hours is the conventional handling.
Clays used as binders exchange and adsorb ionic species non-selectively, and iodide is a small monovalent anion in solution. Co-dosing plausibly reduces the fraction absorbed. The direction is mechanistic and the magnitude has not been quantified.
Ashwagandha extracts have been reported to shift circulating thyroid hormone measures in small human and animal studies, and iodide is the substrate the same axis runs on. Products place them together for that reason. Both the direction and the size of any combined effect are unestablished, and thyroid hormone levels are markers rather than outcomes.
Every unit of potassium iodide carries one potassium ion, though the amount delivered at typical microgram-level iodine doses is negligible against dietary potassium. The point matters only in the high-dose formats where the salt is dosed in milligrams. It is stated for accounting accuracy, not as a potassium source.
Riboflavin is a photosensitiser and iodide is oxidised by light-driven reactions, so the two together in a clear container degrade faster than either would alone. The consequence is a stability and packaging decision. It says nothing about how the two behave in the body.
Talk to a doctor before taking Potassium Iodide if any of these apply to you: thyroid caution, dose sensitive. These are flags to check first, not effects Potassium Iodide is known to cause.
Not medical advice. Show the label to your pharmacist.Potassium iodide dissociates completely in water to potassium and iodide ions, so what the body actually handles is iodide, not the salt. Any iodide salt at an equivalent iodine weight delivers the same species.
Iodide is concentrated by the sodium-iodide symporter, which moves it against a steep gradient using the sodium gradient as the energy source. That transporter is not selective for iodide alone and also carries perchlorate, thiocyanate and pertechnetate.
Thyroid peroxidase, using hydrogen peroxide generated by dual oxidase, oxidises iodide and incorporates it onto tyrosyl residues of thyroglobulin; those iodinated residues are then coupled to form the hormone precursors.
Selenium-dependent deiodinase enzymes remove iodine atoms to convert the storage hormone to its active form and to inactivate both, which is why iodine and selenium supply are two halves of the same handling system.
Iodine is pulled out of mineral ore in Chile or out of salty underground water, cleaned up, then reacted with potassium to make the iodide salt. Because the dose is tiny, it is spread through a carrier powder before it ever reaches a tablet.
From a mineral source, then refined and usually bound to a carrier so the body can take it up.
Commercial iodine comes from two places: the nitrate caliche deposits of northern Chile, where it occurs as iodate, and iodide-rich underground brines associated with natural gas production, chiefly in Japan and the United States.
Brine iodide is oxidised, usually with chlorine, and the elemental iodine is stripped out by blowing air through the solution or by adsorption. Caliche iodate is reduced instead, typically with sulfur dioxide, to precipitate iodine.
Crude iodine is purified by sublimation or by melting under acid, giving the crystalline material that all downstream iodine chemicals are made from.
Iodine reacted with potassium hydroxide gives a mixture of potassium iodide and potassium iodate. The iodate portion is reduced, commonly by heating with a carbon source or by chemical reduction, to convert everything to the iodide. For the iodate product the reaction is stopped at the other end instead.
The salt is crystallised from solution, washed and dried under controlled humidity, since the dry crystal picks up moisture readily.
Content is confirmed by titration and the material is either used neat or diluted onto a carrier, because a microgram-level iodine dose cannot be weighed reliably at full strength in a blend.
Supplied as crystalline salt, as a diluted trituration for tabletting, as an aqueous solution for drops, or as part of a fortification premix.
Labels declare elemental iodine content but rarely state which salt was used, which source region it came from, or what carrier the dilution sits on.
The whole-food sources on file. A supplement closes the gap, it does not replace dinner.
A gram-for-gram figure (how much of each you would eat to match a dose) will appear here once it is sourced and reviewed. This page will not print a number it cannot cite.
These are the studies our verdict leans on, chosen from the 3 we read for Potassium Iodide. The full linked list is below.
7 sources behind our Potassium Iodide verdict: peer-reviewed studies and registered clinical trials. Every one links straight to PubMed, the journal, or ClinicalTrials.gov. Read them yourself.
Evidence surfaced via Semantic Scholar (Allen Institute for AI) and ClinicalTrials.gov. Ranked by study type and citation weight, not cherry-picked.
Read this carefully. These are 104,257 voluntary, unverified reactions reported to the FDA (openFDA). The number mostly reflects how popular Potassium Iodide is, not how risky it is. A report is not proof Potassium Iodide caused anything. It is a signal of what to watch for, nothing more.
Source: openFDA adverse-event reports. Voluntary reporting, not an incidence rate.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.
