Calcium Aluminium Silicate
The short version
A natural aluminosilicate anti-caking agent — used in dry mixes and table salts.
It's permitted and generally considered safe, but there are a few reasons to be mindful — like sensitivities in some people, debated studies, or intake limits. The Safety section below explains the specifics.
Safety profile
JECFA (1985) placed calcium aluminium silicate in a group 'ADI not specified' with silicon dioxide and other silicates; in 2015 it withdrew the tentative specifications because no data were provided. For aluminium from all dietary sources, EFSA (2008) set a tolerable weekly intake of 1 mg/kg body weight per week. Soluble aluminium fraction is the regulatory concern; the silicate matrix itself is essentially inert.
Sources
- JECFA database — Calcium aluminium silicate (INS 556); ADI 1985, specifications withdrawn 2015 — WHO / Joint FAO/WHO Expert Committee on Food Additives, 2015. Safety: group ADI 'not specified' with silicon dioxide and silicates (1985); specs withdrawn 2015
- Commission Regulation (EU) No 380/2012 — aluminium-containing food additives — EUR-Lex / European Union, 2012. EU status: E 556 deleted from the Union list (authorised only until 31 January 2014); EFSA TWI 1 mg/kg bw/week
- Regulation (EC) No 1333/2008 on food additives — consolidated text of 18.08.2026 (Annex II, Part B) — EUR-Lex / European Union, 2026. EU status: E 556 carries footnote (2) 'authorised until 31 January 2014'
- 21 CFR 182.2122 — Aluminum calcium silicate (GRAS) — eCFR / US FDA, 2026. US status: GRAS in table salt, tolerance 2 percent
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.