Magnesium sulphate
A safe mineral salt; high doses act as a laxative.
- Category
- Firming agents
- Vegan
- Yes
- Vegetarian
- Yes
What it is
Commonly known as Epsom salt, used to firm canned vegetables and fortify water.
How it is used in food
Functions as a firming agent, acidity regulator and nutrient. It is used to coagulate tofu, adjust brewing water for beer, and fortify foods with magnesium, an essential mineral many diets lack.
Commonly found in- Canned vegetables
- Bottled water
- Tofu coagulation
Health and safety
Very safe, though large doses have a strong laxative effect.
Magnesium sulphate is on the WHO List of Essential Medicines, given intravenously to prevent seizures in eclampsia. Oral safety is well established; clinical data confirm that single doses of several grams draw water into the bowel and act as an osmotic laxative, which defines its practical intake ceiling.
Regulatory status
| Region | Status | Notes |
|---|---|---|
| Australia & New Zealand FSANZ |
Permitted | Permitted under the FSANZ Food Standards Code. |
| European Union EFSA / European Commission |
Not approved | Not on the EU authorised list of food additives (Annex II). |
| United States FDA (Food and Drug Administration) |
Permitted | Authorised for food use by the FDA (often GRAS for standard additives). |
Identification on labels
- E-number
- E518
Also printed asMagnesium sulfate
Worth knowing
Better known as Epsom salt, it takes its name from a mineral spring in Epsom, England, where it was first extracted in the early 17th century and sold as a cure-all bathing and purgative salt.
Conclusion
A safe mineral salt; high doses act as a laxative.
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Open the appEntry last reviewed 2026-07-28.
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