E555 - Potassium aluminium silicate

At a glance

• What it is: an insoluble mineral salt made of potassium, aluminium, and silica
• What it does: works as an anti-caking agent to prevent lumps in dry foods
• Where you might see it: table salt and salt substitutes, powdered seasonings, dry mixes
• Diet notes: inorganic and mineral-based; not derived from animals

Why is Potassium aluminium silicate added to food?

Manufacturers add E555 to stop powders from sticking together. Moisture can make salts, spices, and mixes clump, which makes them hard to shake, scoop, or blend evenly. Anti-caking agents like E555 keep particles separate so the product stays free-flowing. In EU law, E555 is listed as a food additive with this technological function and specific purity criteria.¹²

What foods contain Potassium aluminium silicate?

You’re most likely to find it in dry and powdered foods where free flow matters. Examples include:

• Salt and salt substitutes
• Powdered seasonings and spice blends
• Instant drink powders and dessert mixes

Its use is authorized in the EU as a food additive; actual use depends on the product and maker.² Not every brand chooses E555—some use other anti-caking agents instead.

What can replace Potassium aluminium silicate?

Common alternatives include:

• Silicon dioxide (E551)
• Calcium silicate (E552)
• Sodium aluminium silicate (E554)
• Calcium aluminosilicate (E556)
• Tricalcium phosphate (E341iii)
• Non-additive options like rice flour or starches in some applications

Choice depends on the food, desired texture, and local rules.

How is Potassium aluminium silicate made?

Food-grade E555 is produced to meet strict identity and purity specifications. In general, manufacturers create an insoluble aluminosilicate by reacting sources of potassium, aluminium, and silicate under controlled conditions. The solid is then washed, dried, and milled to a fine powder. EU specifications define its composition and limits for contaminants like heavy metals.¹

Is Potassium aluminium silicate safe to eat?

In the European Union, E555 is authorized as a food additive and must meet detailed specifications for identity and purity.¹² In the United States, a closely related compound—sodium aluminosilicate—is affirmed as Generally Recognized As Safe (GRAS) for use as an anti-caking agent in food, which supports the safety of this class when used as intended.³

Aluminium intake from all sources has a tolerable weekly intake set by the European Food Safety Authority (EFSA) at 1 mg aluminium per kilogram of body weight.⁴ E555 itself is poorly soluble in water, which means only a very small amount of aluminium is expected to be absorbed from it.¹

Does Potassium aluminium silicate have any benefits?

For consumers, the benefit is simple: less clumping. That means:

• Salt shakes more evenly
• Powdered mixes spoon and dissolve more consistently
• Products stay usable longer after opening when stored dry

Who should avoid Potassium aluminium silicate?

Most people do not need to avoid E555 when it is used as intended. If your doctor has advised you to limit aluminium intake (for example, with certain kidney conditions), you may prefer products that use other anti-caking agents. People who want to avoid mineral additives for personal reasons can look for products made with alternatives like starches or silicon dioxide.

Myths & facts

• Myth: “It adds a lot of aluminium to your body.” Fact: E555 is insoluble, so only a small amount of aluminium is expected to be absorbed from it.¹
• Myth: “It isn’t approved.” Fact: E555 is authorized for use as a food additive in the EU and must meet strict specifications.²
• Myth: “It’s the same as silicone.” Fact: Silicones are polymers; E555 is a mineral aluminosilicate. Different chemistry and uses.

Potassium aluminium silicate in branded foods

Ingredient lists are the best way to check. Look for “E555” or “potassium aluminium silicate” on:

• Table salt and salt substitutes
• Seasoning blends and rubs
• Instant drink and dessert powders

If you prefer to avoid it, choose products that list other anti-caking agents (for example, silicon dioxide) or none at all.

References

Footnotes

1. Commission Regulation (EU) No 231/2012 — Specifications for food additives (includes potassium aluminium silicate, E 555). https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32012R0231 ↩ ↩² ↩³ ↩⁴ ↩⁵

2. Regulation (EC) No 1333/2008 — Food additives (Union rules and authorizations). https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32008R1333 ↩ ↩² ↩³ ↩⁴

3. 21 CFR 182.2727 — Sodium aluminosilicate; affirmed as GRAS as an anticaking agent. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-182/subpart-C/section-182.2727 ↩

4. Safety of aluminium from dietary intake — EFSA Scientific Opinion (Tolerable weekly intake 1 mg/kg bw). https://doi.org/10.2903/j.efsa.2008.754 ↩