E556 - Calcium aluminium silicate

Synonyms: E556Calcium aluminium silicateCalcium aluminosilicateCalcium silicoaluminateAluminium calcium silicate

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Calcium aluminium silicate (E556) is an anti-caking agent that helps dry foods like salt and seasoning blends stay free-flowing. It is a synthetic mineral-like powder from the aluminosilicate family and is used in very small amounts. European regulators have set specifications and reviewed its safety for use in foods.

At a glance

Here is a quick overview of what E556 is and how it is used.

Role in food: anti-caking agent that prevents clumping by keeping powders dry and free-flowing.
Where you’ll see it: mostly in dry, powdered products such as table salt, salt substitutes, and some seasoning mixes.
What it is: a calcium aluminosilicate, a mineral-like material containing calcium, aluminium, silicon, and oxygen.
Other names: calcium aluminosilicate, calcium silicoaluminate, aluminium calcium silicate.
Appearance and taste: white, fine powder that is essentially tasteless and odorless at typical use levels.

Why is Calcium aluminium silicate added to food?

Manufacturers add E556 to reduce clumping in dry foods so they pour and measure consistently. This helps keep products like salt and spice blends easy to use throughout their shelf life, especially in humid conditions.¹

What foods contain Calcium aluminium silicate?

You are most likely to find E556 in foods that need to stay free-flowing during storage and handling. Examples include:

Table salt and salt substitutes
Seasoning blends and some dry mixes
Certain powdered soups, sauces, and food supplement powders

These are typical authorized uses in the European Union for anti-caking purposes at reported use levels.¹

What can replace Calcium aluminium silicate?

Depending on the product and process, formulators may choose other anti-caking agents or simple process controls.

Common alternatives: silicon dioxide, calcium silicate, talc, tricalcium phosphate, and cellulose.
Non-additive approaches: better packaging, drier storage, and controlled humidity can also reduce caking.

How is Calcium aluminium silicate made?

Food-grade calcium aluminium silicate is produced as a synthetic, amorphous aluminosilicate that meets identity and purity specifications set in European Union legislation.² In practice, manufacturers produce a fine, free-flowing powder designed to disperse easily and function effectively at very low use levels.

Is Calcium aluminium silicate safe to eat?

The European Food Safety Authority (EFSA) re-evaluated sodium, potassium, and calcium aluminium silicates in 2018 and concluded that exposure to these additives from their reported uses was not of safety concern for consumers.¹ EFSA also notes that the aluminium in these aluminosilicates is tightly bound and poorly available for absorption due to their low solubility.¹

Separately, EFSA has established a tolerable weekly intake (TWI) for aluminium of 1 mg per kilogram of body weight per week from all sources in the diet.³ This TWI covers total aluminium exposure, not just from E556.

Does Calcium aluminium silicate have any benefits?

For everyday cooking and eating, the benefit is simple: powders that pour. Keeping salt and spice mixes free-flowing helps with consistent measuring and even flavor. For manufacturers, this also improves handling, packaging, and shelf-life quality.

Who should avoid Calcium aluminium silicate?

Most people do not need to avoid E556 when it is used as intended. However, people with severe kidney (renal) impairment may have reduced ability to eliminate aluminium from the body; clinicians sometimes advise these patients to limit aluminium exposure from all sources.⁴ If you have kidney disease, follow your healthcare provider’s advice about overall aluminium intake.

Myths & facts

A few common points often cause confusion—here’s what the science says.

Myth: “It releases aluminium metal into food.” Fact: In calcium aluminium silicate, aluminium is part of an insoluble aluminosilicate structure and is poorly bioavailable; EFSA identified no safety concern at reported uses.¹
Myth: “Anti-caking agents are all the same.” Fact: Different agents, such as silicon dioxide or calcium silicate, have different chemistries, use levels, and best-fit applications.

Calcium aluminium silicate in branded foods

On ingredient lists, look for “E556,” “calcium aluminium silicate,” or “calcium aluminosilicate.” You’ll most often see it on salts, salt substitutes, and some seasoning or dry mix labels. If you prefer to avoid it, choose products labeled as having no anti-caking agents or those using alternatives like silicon dioxide or cellulose.

References

Re-evaluation of sodium aluminium silicate (E 554), potassium aluminium silicate (E 555) and calcium aluminium silicate (E 556) as food additives — EFSA Journal. https://www.efsa.europa.eu/en/efsajournal/pub/5087 ↩ ↩² ↩³ ↩⁴ ↩⁵
Commission Regulation (EU) No 231/2012 laying down specifications for food additives — EUR-Lex. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩
Safety of aluminium from dietary intake; establishment of a TWI — EFSA Journal. https://www.efsa.europa.eu/en/efsajournal/pub/754 ↩
Toxicological Profile for Aluminum — Agency for Toxic Substances and Disease Registry (ATSDR), U.S. CDC. https://www.atsdr.cdc.gov/toxprofiles/tp22.pdf ↩