Potassium iodide

No E-numberVitamins & mineralsOrigin: Mineral

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VeganYes

It is a mineral salt.

Gluten-freeYes

HalalYes

KosherYes

KetoYes

No carbohydrate.

Low-FODMAPYes

The short answer

Potassium iodide is the iodine added to iodised table salt. Iodine has one of the narrowest windows of any nutrient: too little and the thyroid enlarges, too much and the thyroid misbehaves, so EFSA caps adults at 600 micrograms a day.

78/100

Use in moderation

Safe in small amounts; may bother some people or raise blood sugar.

E-numberNone

Comes fromMineral

What it doesVitamins & minerals

Glycemic index—

Daily limitNot set

Also calledPotassium iodide, Potassium iodide (iodine)

Rules by country

🇺🇸 US FDAApproved

🇪🇺 European UnionApproved with limits

🇨🇦 Health CanadaApproved

CaliforniaNo extra rules

Potassium iodide has no E-number: it is a nutrient source of iodine, not an additive. In the United States it is what turns table salt into iodised salt, and 21 CFR 172.375 permits it as an iodine source. In the EU each country sets its own iodised salt standard. EFSA set an upper level of 600 micrograms a day for adults.

Daily limit: Experts haven’t set a number because normal food amounts are far below any level of concern.

What is it?

Potassium iodide is a white crystalline salt, and the iodine in it is the part that does the work. The thyroid needs a steady trace to make the hormones that set body temperature, energy and heart rhythm, and it cannot store iodine, so the intake has to be steady. European iodised salt carries roughly 20 to 40 micrograms of iodine per gram of salt, and a pinch is a small share of a day's need.

Where it comes from: Potassium iodide is a white salt of potassium and iodine, made from iodine recovered from seaweed and Chilean caliche nitrate. Almost all of it goes into table salt as iodised salt, and the rest into infant formula and vitamin pills.

Why it’s in food

Iodises table salt
Forts infant formula
Supplies iodine in supplements

Often found in

Table saltIodised table saltInfant formulaMultivitamin tabletsIodine supplements

Also listed as: Potassium iodide, Potassium iodide (iodine), Iodized salt (source), KI, Potassium iodide (source)

Health & gut impact

The thyroid needs a steady traceBenefit

EFSA set an adequate intake of 150 micrograms of iodine a day for adults and an upper level of 600 micrograms. The gap between them is narrow because the thyroid stores nothing, so a day with no iodine at all is a day with no spare.

EFSA, dietary reference values for iodine

Both ends of the range go wrongUnder study

Too little iodine enlarges the thyroid and slows metabolism, and too much drives the gland the other way. In people with thyroid disease even a modest excess can be enough to trigger hyperthyroidism, which is why EFSA set a limit rather than leaving it open.

EFSA Journal, scientific opinion on iodine

Salt iodisation as public healthBenefit

Iodising salt is one of the most successful public health interventions in nutrition because it reaches people who eat the least variety. WHO estimates that about a third of people worldwide still live with diets short of iodine, mostly where the salt is not iodised.

WHO, iodine

What can I use instead?

Seaweed

Ratio: A small serving covers a day's iodine, but the amount varies widely by plant

Best for: Getting iodine without iodised salt

Milk and dairy

Ratio: A glass of cow's milk carries a small, steady amount

Best for: People who avoid table salt

An iodine supplement

Ratio: The daily dose on the label rather than a high-dose tablet

Best for: Travel and low-salt diets

More vitamins & minerals:

CholineCholine is a nutrient most people get enough of from eggs, meat and soy, so it is rarely something to hunt down. It is added on purpose to infant formula, where the amount is regulated, and EFSA sets 400 mg a day for adults.Use in moderation Ferrous sulfateFerrous sulfate is the iron added to flour, bread and cereals, and it is safe at fortification amounts. The catch is the dose: a large single serving upsets the stomach, so read the milligram amount on the label, not the product count.Use in moderation Folic acid (Vitamin B9)Folic acid is the synthetic form of vitamin B9, and it is added to flour, bread and breakfast cereals on purpose. It is safe at fortification levels, but EFSA caps it at 0.6 mg a day for adults because a large intake can hide a vitamin B12 deficiency.Use in moderation Niacin (Vitamin B3)Niacin is vitamin B3 in the nicotinic acid form, added to flour and cereals because many diets fall short of it. Fortification amounts are small and safe, but a 100 mg supplement is a bigger dose, and that much nicotinic acid makes many people flush.Use in moderation

Common questions

Do I need iodised salt if I eat seafood?

It depends on how much and how often. Seaweed and shellfish carry iodine, but the amount varies widely between plants and species, so iodised salt remains the most reliable way to know what you are getting.

Is iodine in seaweed the same as iodine in iodised salt?

It is the same element delivered in different compounds. Seaweed gives you iodine bound in organic molecules, while potassium iodide is a simple inorganic salt, and the dose per gram of seaweed is far less predictable.

Can too much iodine cause problems?

Yes. Excess iodine can push the thyroid into hyperthyroidism or into sluggishness, and it is one of the nutrients where the gap between what you need and what harms you is narrow. People with existing thyroid disease are advised to keep to the label amounts.

Is Potassium iodide safe?

Use in moderation (78/100). Potassium iodide has no E-number: it is a nutrient source of iodine, not an additive. In the United States it is what turns table salt into iodised salt, and 21 CFR 172.375 permits it as an iodine source. In the EU each country sets its own iodised salt standard. EFSA set an upper level of 600 micrograms a day for adults.

Is Potassium iodide vegan?

Yes. It is a mineral salt.

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Scientific sources & regulatory citations

21 CFR 172.375 (US FDA)
EFSA, dietary reference values for iodine
EFSA Journal, scientific opinion on iodine
WHO, iodine

CAS 7681-11-0