Back to catalogSafety
E518AcidulantLow concern
Magnesium Sulfate
In plain words
The short version
'Epsom salt' — a firming agent, tofu coagulant, and brewing salt that also supplies magnesium.
Why it's green
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Safety profile
No ADI specified. Poorly absorbed; larger oral amounts act as a saline laxative — the traditional use of Epsom salts.
The detail
'Epsom salt', occurring naturally as the mineral epsomite; also produced from magnesium sources.
Firming agent and tofu coagulant, a brewing salt used to adjust water hardness, and a magnesium source and nutrient.
Colorless crystals, freely water-soluble, with a bitter taste.
GRAS in the US. In the EU, magnesium sulphate is not on the Union list of authorised food additives, but it may be added to foods as a source of magnesium.
Sources
- WHO JECFA database — Magnesium sulfate (INS 518) — Joint FAO/WHO Expert Committee on Food Additives (WHO), 2007. Safety: ADI not specified; Epsom salt synonym
- 21 CFR 184.1443 — Magnesium sulfate (eCFR, current as of 13 Oct 2026) — US eCFR / Office of the Federal Register, 2026. Origin (mineral epsomite) and US GRAS status
- EUR-Lex — Regulation (EC) No 1925/2006 on the addition of vitamins and minerals and of certain other substances to foods, consolidated version of 26 November 2025 (Annex II) — Publications Office of the European Union, 2025. EU status: allowed as a mineral source (magnesium) added to foods
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.