E-numbers / Other additives / E522
also: Aluminium potassium sulfate · Potash alum · Potassium alum · Common alum
A mineral salt (potassium alum) used as a firming agent in candied fruit and egg whites. Adds aluminium to the diet.
Scan a barcode to check a food for aluminium potassium sulphate. NutraSafe Pro · £3.99/month · iOS
Aluminium accumulates in the body over time.
1
of the 43,325 UK supermarket foods we checked declare E522 in their ingredients
That is under 0.1%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. Aluminium accumulates in the body over time. Total dietary aluminium from all sources, including E522, can push some people, especially children, above the weekly limit regulators consider tolerable. High aluminium body burden is linked to effects on the nervous system in animal studies.
Aluminium potassium sulphate, also called potassium alum, is a naturally occurring mineral salt with the formula KAl(SO4)2. It is the same compound historically used in pickling and as a mordant in dyeing. As a food additive it is a white crystalline powder that dissolves readily in water.
Acts primarily as a firming agent: aluminium ions cross-link with proteins and pectin in plant and egg-white tissue, stiffening the structure and preventing softening during cooking, candying or soaking. It also has mild acidity-regulating and astringent properties.
Used in candied, crystallised and glacé cherries and other candied or glazed fruits and vegetables; industrially produced bottled or preserved egg whites; some egg-based and seafood dishes made to commercial scale. On a UK label it appears as 'aluminium potassium sulphate' or 'E522'.
EFSA set a tolerable weekly intake (TWI) of 1 mg aluminium per kilogram of body weight per week in 2008, covering all dietary aluminium sources combined. When EFSA re-evaluated the aluminium sulphate group (E520-523) in 2018, it found that total aluminium intake from food in European populations, particularly children, can approach or exceed this TWI when all sources are added together. The contribution from food additives such as E522 is a fraction of this total, but it is not negligible.
EFSA established a tolerable weekly intake of 1 mg aluminium per kg body weight per week, based principally on neurodevelopmental effects observed in animal studies.
In the 2018 re-evaluation of aluminium sulphates (E520-523), EFSA confirmed that the TWI remained 1 mg Al/kg bw/week and noted that some population groups, particularly children, may exceed it when all dietary aluminium sources are considered together.
Animal studies at higher aluminium doses have shown effects on the developing nervous system, including changes in behaviour and neurotransmitter levels. These findings informed the TWI. Human epidemiological data on dietary aluminium from food additives specifically are limited; most human research concerns aluminium from drinking water or occupational exposure at far higher levels.
Animal studies show neurotoxic effects at higher aluminium doses, including neurobehavioural changes in developing animals, which formed the primary basis for EFSA's TWI of 1 mg Al/kg bw/week.
JECFA set a provisional tolerable weekly intake of 2 mg Al/kg bw/week in 2011, derived from a NOAEL of 30 mg/kg bw/day in a neurodevelopmental study with a 100-fold safety factor.
Aluminium from food is poorly absorbed through the gut, typically less than 1% of ingested aluminium enters the bloodstream. However, absorbed aluminium is excreted slowly and can accumulate in bone and soft tissue with long-term exposure. People with impaired kidney function excrete it even more slowly and are considered a higher-risk group.
Gastrointestinal absorption of aluminium from food is low (generally below 1%), but aluminium that is absorbed is retained in bone, brain and other tissues and is eliminated slowly via the kidneys.
Children are the group most likely to approach or exceed the tolerable weekly intake from all dietary sources combined. People with chronic kidney disease excrete aluminium poorly, so it accumulates faster in their tissues. Anyone monitoring aluminium intake should check labels for 'aluminium potassium sulphate' or 'E522', most commonly on candied or glacé cherries and commercial egg-white products.
E522 is used in a narrow range of foods at low levels, and absorption from the gut is very low. On its own, it contributes a small fraction of total dietary aluminium. The complication is that aluminium is everywhere in the food supply, and regulators assess exposure from the total: grains, tea, cocoa, drinking water, food contact materials, antacids and aluminium-containing food additives together. EFSA's 2018 review found that some European children may collectively exceed the tolerable weekly intake from all these sources. The science on what chronic low-level aluminium exposure does to humans at real-world dietary doses remains genuinely uncertain. The strongest signals come from animal neurodevelopment studies; the direct human evidence at food-additive exposure levels is limited. Regulators continue to permit E522 in its current narrow uses while noting that overall aluminium exposure needs watching, particularly in children.
No. E522 is permitted in the UK under the assimilated EU Regulation 1333/2008 for a small number of food categories, principally candied and glacé fruits and preserved egg whites, at specified maximum levels.
By itself, E522 in permitted foods adds a small amount of aluminium. Regulators focus on total dietary aluminium from all sources combined, including grains, tea, cocoa, drinking water and other aluminium-containing additives. EFSA found that some population groups, especially children, can approach or exceed the tolerable weekly intake from these combined sources.
Mainly candied, crystallised and glacé cherries and similar confected fruits or vegetables, and some commercially produced bottled or preserved egg whites. It is not a widely used additive and does not appear in most everyday foods.
Yes. Aluminium potassium sulphate is a mineral salt with no animal-derived ingredients. Its use in egg-white products does not affect its own vegan status, though those specific products are not vegan.
Last reviewed: 20 June 2026
It's the only app that does thisUKJaneK
You Need This AppGmac2005
Best AppGK getting skinny UK App Store reviews
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
NutraSafe Pro · £3.99/month · iOS
