Magnesium Sulphate

About

What it is and where it shows up.

Magnesium sulphate (MgSO4) is an inorganic salt of magnesium used in food as a firming agent, flour treatment agent, and mineral nutrient supplement. It occurs naturally as the mineral epsomite (heptahydrate form) and is widely used to fortify foods with magnesium, an essential dietary mineral.

Safety summary

The regulatory and scientific consensus.

Magnesium sulphate is considered safe for the general adult population; JECFA has established an ADI 'not specified', reflecting a broad safety consensus at typical food-use levels. There is no established upper limit (UL) for magnesium from food sources, though high supplemental doses can cause osmotic diarrhoea and, in cases of severe excess, hypermagnesaemia. Individuals with impaired kidney function are the principal sensitive group, as the kidneys are the primary route of magnesium excretion.

Regulatory landscape

What food-safety regulators have decided.

Jurisdiction	Status	Note
FSANZ (Food Standards Australia New Zealand) (Australia)	Approved	Permitted as food additive INS 518 under Australia New Zealand Food Standards Code; approved uses include firming agent and mineral supplement.source
Health Canada (Canada)	Approved	Permitted as a food additive and mineral nutrient in Canada under the Food and Drug Regulations; functional use as firming agent and nutrient supplement.source
EFSA (European Food Safety Authority) (European Union)	Approved	Authorised as food additive E518 under Regulation (EC) No 1333/2008; permitted as firming agent and flour treatment agent in specific food categories. ADI 'not specified' by JECFA; no numerical ADI set by EFSA.source
FSSAI (Food Safety and Standards Authority of India) (India)	Approved	Permitted as food additive INS 518 under FSSAI Food Safety and Standards (Food Products Standards and Food Additives) Regulations; functional use as firming agent and nutrient supplement.source

Who should approach with care

Whose guidance would steer them away.

Kidney Disease — The kidneys are the primary route of magnesium excretion; individuals with renal impairment cannot efficiently clear excess magnesium, risking hypermagnesaemia even at supplemental doses typically safe for healthy adults.

Heart Disease — Elevated magnesium levels (hypermagnesaemia) can cause cardiac conduction disturbances including bradycardia and hypotension; patients with pre-existing cardiac conditions should consult a doctor before consuming high-dose magnesium supplements.

Infants — Infants have immature renal function and limited capacity to excrete excess magnesium; supplemental magnesium sulphate in infant formula or foods should not exceed age-appropriate reference intakes.

Pregnancy — While magnesium sulphate is used therapeutically in obstetric emergencies, high supplemental intake from food additives during pregnancy should be discussed with a healthcare provider to avoid exceeding tolerable intake levels.

Ibs — Magnesium sulphate has an osmotic laxative effect at higher doses; individuals with irritable bowel syndrome may experience exacerbated diarrhoea or gastrointestinal cramping.

Research citations

The sources behind this verdict.

1FAO/WHO (JECFA). GSFA Online Food Additive Details for Magnesium Sulfate (INS 518). fao.org
2FDA. FDA Food Substance Database – Magnesium Sulfate (GRAS, 21 CFR 184.1443). hfpappexternal.fda.gov
3PubChem (NIH/NLM). Magnesium Sulfate – Compound Summary (CID 24083). pubchem.ncbi.nlm.nih.gov
4WHO. WHO/FAO JECFA Food Additives – Magnesium Sulfate. apps.who.int
5FDA. Agency Response Letter GRAS Notice No. GRN 000618 – Magnesium RDA and UL, 2018. fda.gov

Independently researched5 citations