Magnesium carbonates

Magnesium carbonates — including magnesium carbonate (MgCO₃) and magnesium hydrogen carbonate — are white, odourless inorganic salts used primarily as anti-caking agents and pH regulators in food. They function as free-flow agents in powdered products such as table salt, spice mixes, and dried dairy ingredients, preventing clumping by absorbing moisture and keeping particles separate.

JECFA's ADI is "not specified," evaluated in 1975. Magnesium carbonate is a well-tolerated inorganic mineral salt. In the digestive tract it reacts with stomach acid to release magnesium ions and carbon dioxide, contributing a small amount of bioavailable magnesium. No adverse effects have been identified at any realistic dietary exposure. It is also used as an antacid in pharmaceutical preparations at much higher concentrations than food additive use.

Magnesium carbonates are approved in the EU, US (GRAS), UK, and globally. They are found in powdered food products, salt, baking powder, and as mineral supplement carriers. The magnesium contribution at food additive concentrations is nutritionally modest. For healthy adults there are no safety concerns; magnesium is an essential mineral that most Western diets provide at adequate but not excess levels.