E559 - Aluminium silicate

At a glance

• Other names: E559, aluminium silicate, kaolin
• What it does: Anti-caking agent; sometimes a defoaming aid
• Typical in: Powdered food mixes, seasonings, and other dry goods
• Source: Mined kaolin clay that is purified and milled
• Solubility: Practically insoluble in water
• Safety: Permitted in the U.S. and EU within specifications and good manufacturing practice

Why is Aluminium silicate added to food?

Manufacturers add aluminium silicate to help powders stay dry and free-flowing. As an anti-caking agent, it absorbs surface moisture and reduces clumping in dry blends. In the U.S., kaolin is affirmed as Generally Recognized as Safe (GRAS) for use in food as an anticaking agent and as a defoaming aid, when used at levels consistent with good manufacturing practice.¹

What foods contain Aluminium silicate?

You’re most likely to see E559 in dry, powdered products where caking is a concern, such as seasoning blends, drink mixes, or other shelf-stable powder blends. Its use is permitted in the EU under established purity specifications, and in the U.S. under GRAS conditions for suitable functions.²¹

Because brands choose from several anti-caking options, E559 may be less common than alternatives like silicon dioxide or sodium aluminium silicate in some categories.

What can replace Aluminium silicate?

Depending on the recipe and regulatory allowance, formulators might use:

• Silicon dioxide
• Calcium silicate
• Magnesium silicates or talc
• Tricalcium phosphate
• Microcrystalline cellulose
• Other aluminosilicates such as sodium aluminium silicate, potassium aluminium silicate, or calcium aluminium silicate
• Clay-based alternatives like bentonite in certain applications

The right choice depends on taste neutrality, regulatory limits, flow performance, and labeling goals.

How is Aluminium silicate made?

E559 is derived from natural kaolin clay. The mineral is mined, refined to remove impurities, and milled to a fine powder that meets food-grade specifications. In the EU, its composition is defined as mainly hydrated aluminium silicate with strict limits for contaminants and defined physical properties; it is practically insoluble in water.²

Is Aluminium silicate safe to eat?

• United States: Kaolin is affirmed by the U.S. Food and Drug Administration (FDA) as GRAS for use in food as an anti-caking agent and defoaming aid when used according to good manufacturing practice.¹
• European Union: The EU sets binding identity and purity specifications for aluminium silicate (E559) used in food, which manufacturers must meet.²

Aluminium silicate is poorly soluble, and dietary aluminium from many insoluble forms is minimally absorbed in the gut.²³ Even so, overall aluminium intake from all sources should remain below the tolerable weekly intake (TWI) of 1 mg aluminium per kilogram of body weight set by the European Food Safety Authority (EFSA).⁴

Does Aluminium silicate have any benefits?

For foods, the benefits are practical:

• Helps powders pour easily and measure consistently
• Reduces clumping during storage
• Can support consistent texture and appearance in dry mixes

For manufacturers, it can improve processing efficiency by keeping ingredients free-flowing.

Who should avoid Aluminium silicate?

Most people don’t need to avoid E559 when it’s used as intended. However:

• People with severe kidney impairment may be advised to limit aluminium exposure in general, because the body clears aluminium primarily through the kidneys.³
• Infants and certain sensitive groups can be more vulnerable to high aluminium exposure; minimizing unnecessary exposure is prudent.³

If you have a condition requiring reduced aluminium intake, discuss overall sources with your healthcare provider.

Myths & facts

• Myth: Aluminium silicate dissolves in the body and releases lots of aluminium. Fact: It is practically insoluble in water; oral absorption of aluminium from insoluble compounds is low.²³
• Myth: E559 is banned in the U.S. or EU. Fact: It is permitted in both regions within specifications and good manufacturing practice.¹²
• Myth: Any aluminium additive causes Alzheimer’s disease. Fact: Major health agencies report no conclusive evidence that typical dietary aluminium exposure causes Alzheimer’s; maintaining prudent overall exposure is still recommended.³

Aluminium silicate in branded foods

On ingredient lists, look for “aluminium silicate,” “kaolin,” or “E559” (in the EU). You may see it in:

• Dry seasoning and spice blends
• Powdered beverage mixes
• Dry soup or sauce bases
• Other powdered or granulated foods where caking is a concern

Because companies can choose among several anti-caking agents, the exact additive varies by brand and product.

References

Footnotes

1. 21 CFR 186.1256 Kaolin — U.S. FDA. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-186/section-186.1256 ↩ ↩² ↩³ ↩⁴

2. Commission Regulation (EU) No 231/2012 (food additive specifications), entry for E 559 aluminium silicate — European Union. https://eur-lex.europa.eu/eli/reg/2012/231/oj ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

3. Toxicological Profile for Aluminum — ATSDR/CDC. https://www.atsdr.cdc.gov/toxprofiles/tp22.pdf ↩ ↩² ↩³ ↩⁴ ↩⁵

4. Safety of aluminium from dietary intake; establishment of a TWI — EFSA Journal. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2008.754 ↩