E-numbers / Other additives / E523
also: Aluminium ammonium sulfate · Ammonium alum · Ammonia alum
A mineral salt used as a firming agent and in baking powders. One of several food additives that add to total dietary aluminium intake.
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Aluminium accumulates in the body and, in animal studies, damages the brain and nervous system at sustained higher doses.
Why it’s worth knowing. Aluminium accumulates in the body and, in animal studies, damages the brain and nervous system at sustained higher doses. Regulators set a weekly intake limit for total aluminium from all dietary sources combined, and some people's diets already approach that limit before additive sources are counted.
Aluminium ammonium sulphate is an inorganic double salt, also known as ammonium alum. It consists of aluminium ions, ammonium ions, and sulphate, forming colourless crystals that dissolve readily in water. It occurs naturally in some minerals but is produced industrially for food use.
It acts as a firming agent, keeping fruits and vegetables firm during processing, and functions as an acid component in chemical raising agents (baking powder), where it reacts with sodium bicarbonate to release carbon dioxide and cause dough to rise. It can also act as a flour treatment agent in small quantities.
Found in commercially processed candied and crystallised fruits, some canned vegetables, certain baked goods using commercial raising agents, and occasionally in cocoa and chocolate products. On a UK ingredient label it appears as 'aluminium ammonium sulphate' or 'E523'.
Animal studies, mainly in rats, show that aluminium absorbed into the body crosses into the brain and causes nerve cell damage at sustained elevated doses. These findings are the scientific basis for the weekly intake limit set by European regulators. Human evidence for neurotoxicity from dietary aluminium at typical food levels is much weaker, but the limit was set conservatively on the animal data.
Animal studies show aluminium causes neurotoxicity at high sustained doses, including effects on nerve cell structure and function. EFSA used these data to set a group Tolerable Weekly Intake of 1 mg/kg body weight per week for total aluminium from all dietary sources.
In the 2018 re-evaluation of E520-523 and E541, EFSA found that these aluminium-containing food additives contribute to total dietary aluminium exposure. Exposure from these additives alone is small relative to the TWI, but they add to background aluminium from food, water, and other sources.
Aluminium enters the diet from natural levels in food and water, cookware, and multiple food additives including E523. EFSA's 2008 review found that some European consumers' total aluminium intake can approach or exceed the weekly limit when all these sources are combined. Children who eat relatively more processed or baked goods may face proportionally higher exposure per kilogram of body weight.
EFSA estimated that total dietary aluminium intake in some European population groups, including children at the high end of consumption, can reach or slightly exceed the Tolerable Weekly Intake of 1 mg/kg body weight per week when all food sources are combined.
Some observational studies found higher aluminium levels in brain tissue of people with Alzheimer's disease. This generated public interest and concern, but decades of research have not established that dietary aluminium causes Alzheimer's. Regulators and mainstream scientific bodies have not classified aluminium as a cause of Alzheimer's; the association remains unresolved.
Epidemiological and neuropathological studies have reported elevated aluminium concentrations in brains of Alzheimer's patients, but these findings do not establish a causal relationship and remain contested in the scientific literature.
People with impaired kidney function clear aluminium more slowly, so aluminium accumulates more readily in their bodies. Parents of young children may wish to note that children face higher relative exposure per kilogram of body weight. Look for 'aluminium ammonium sulphate' or 'E523' on the label, and consider how many other aluminium-containing additives (E520-E541 range) appear in the same product or in the wider diet.
E523 is one of several aluminium-based food additives (E520 through E523, E541) that have been in use for a long time. The regulator's concern is not with E523 in isolation but with total dietary aluminium from all sources combined. The weekly intake limit was set from animal neurotoxicity data, and some consumers, particularly children with high intakes of processed and baked goods, can approach or reach that limit before additive sources from E523 are added. The Alzheimer's question has attracted decades of research and remains genuinely unresolved rather than dismissed. The science on aluminium and the brain is not finished.
No. E523 is an approved food additive in the UK under the assimilated EU Regulation 1333/2008, permitted in a limited set of food categories including candied fruits and certain baked goods.
Regulators set a Tolerable Weekly Intake for total dietary aluminium because animal studies show it can damage the nervous system at sustained higher doses. Approving additives like E523 does not mean there is no concern; it means exposure from authorised uses is considered manageable within that limit, though some people's total intake from all sources combined can approach the limit.
Candied, crystallised and glacé fruits, some commercial baked goods using multi-ingredient raising agents, and occasionally cocoa and chocolate products. It is relatively rare compared with other food additives.
Yes. Aluminium ammonium sulphate is a mineral salt with no animal-derived components and is suitable for vegan and vegetarian diets.
Last reviewed: 20 June 2026
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