Calcium aluminium silicate
A mineral anti-caking agent containing aluminium, once used in powdered foods. No longer permitted in UK or EU food since 2014.
Aluminium accumulates in the body and has been linked to nerve and bone damage. EU regulators removed this additive because aluminium from food sources was already exceeding the safe weekly intake before factoring in this additive.
What is it?
Calcium aluminium silicate is a synthetic mineral compound made from calcium, aluminium, silicon and oxygen. It forms fine, light particles that do not clump easily. It belongs to the aluminium silicate family, which includes related E-numbers such as sodium aluminium silicate (E554) and potassium aluminium silicate (E555).
What does it do?
It works as an anti-caking agent: the particles coat the surface of powdered or granular food ingredients, reducing moisture absorption and preventing the powder from clumping. This keeps products such as table salt, powdered soups and seasoning blends free-flowing.
Where you will see it
Historically used in table salt, powdered soups, dried egg products, and seasoning mixes. Because it was deleted from the EU and UK permitted additives list in 2014, it should not appear in any food placed on the UK market after that date. If you see it on a label, the product may be an import from outside the UK and EU, or the label is out of date. It would appear as 'calcium aluminium silicate' or 'E556'.
What the science says
Aluminium and the nervous system
Aluminium is not an essential nutrient and accumulates in the body over time, particularly in bone and brain tissue. Animal studies and some human epidemiological work have raised concerns about neurological effects at higher exposures. EFSA set a tolerable weekly intake (TWI) for aluminium of 1mg per kilogram of body weight per week, based on effects seen in animal studies on the nervous system and reproductive function.
EFSA set a tolerable weekly intake for aluminium of 1mg per kg of body weight per week, derived from animal data showing effects on the nervous system and reproductive function.
EFSA found that dietary aluminium exposure from all sources, including food additives, already exceeded the TWI in high consumers before any contribution from aluminium silicate additives was added.
Why the EU removed this additive from the permitted list
The European Commission deleted E556 from the list of permitted food additives in 2012, with the deletion taking effect in 2014. The stated reason was that calcium aluminium silicate could be replaced by other anti-caking agents that do not contribute aluminium to the diet. Because overall aluminium exposure from food was already of concern, removing sources of aluminium from additives was a precautionary measure.
Commission Regulation (EU) No 380/2012 deleted E556 from Annex II of Regulation (EC) No 1333/2008, on the basis that it could be replaced by alternative anti-caking agents not containing aluminium.
Safety data gap for the aluminium silicate group
EFSA's 2020 re-evaluation of the closely related E554 and E555 found that the safety of those additives could not be properly assessed because the required toxicological and physicochemical data had not been submitted. The panel noted that estimated aluminium exposure from E554 alone reached 2.13mg/kg body weight per week in children, more than double the TWI. E556 was not covered by this re-evaluation but shares the same core aluminium-exposure concern.
EFSA concluded that the safety of sodium aluminium silicate (E554) and potassium aluminium silicate (E555) could not be assessed due to insufficient toxicological data, and noted that aluminium exposure from E554 reached up to 2.13mg/kg body weight per week in children, exceeding the TWI of 1mg/kg body weight per week.
Where it stands with the regulators
Who should be careful
Because E556 is not permitted in UK or EU food, consumers should not encounter it in products sold here. If a product sold in the UK lists 'calcium aluminium silicate' or 'E556', it should be treated as a labelling or import concern and reported to the Food Standards Agency. Children and people with kidney disease are considered most vulnerable to aluminium accumulation.
The honest read
The scientific concern with aluminium-containing food additives is real and was the direct cause of this additive being removed from the approved list. Aluminium accumulates in the body and the evidence base, primarily from animal studies, pointed to effects on nerves and bone that regulators were not comfortable dismissing. The story for E556 is not contested science, it is settled enough for regulators to act: the additive was cut from the list because better alternatives exist and adding more aluminium to the diet was not justifiable. What remains unresolved is the precise level of risk to humans from chronic low-level aluminium exposure across all dietary sources, which is why EFSA maintains an active TWI and continues to evaluate aluminium-containing substances.
Related additives
Common questions
Is E556 banned in the UK?
Yes. E556 was removed from the EU list of permitted food additives in 2014 under Commission Regulation (EU) No 380/2012, and the UK carried this prohibition into domestic law via the Food Additives, Flavourings, Enzymes and Extraction Solvents (Amendment etc.) (EU Exit) Regulations 2019. The UK FSA regulated products register records no current authorisation for E556. Food containing E556 should not legally be sold in the UK.
Why was E556 removed from the permitted additives list?
The European Commission removed it because effective alternatives exist that do not contain aluminium. Regulators were concerned that aluminium intake from food was already at or above the safe weekly level without adding more through this additive. Removing unnecessary aluminium sources from the diet was the straightforward call.
What foods contain E556?
Before 2014 it was used in table salt, powdered soups, dried egg products and seasoning blends as an anti-caking agent. In the UK and EU it should not be present in any food on the market today. Foods imported from outside the UK and EU may still use it where local rules permit.
Is E556 vegan?
Yes. Calcium aluminium silicate is a synthetic mineral compound with no animal-derived ingredients.
Sources
- UK FSA Approved Additives and E Numbers
- UK FSA Regulated Products Register - food authorisations guidance
- Commission Regulation (EU) No 380/2012 amending Annex II to Regulation (EC) No 1333/2008 as regards aluminium-containing food additives
- The Food Additives, Flavourings, Enzymes and Extraction Solvents (Amendment etc.) (EU Exit) Regulations 2019 (SI 2019/860)
- EFSA - Re-evaluation of sodium aluminium silicate (E554) and potassium aluminium silicate (E555) as food additives (PMC7448050)
- EFSA AFC Panel - Safety of aluminium from dietary intake (PubMed)
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