Magnesium hydroxide

Magnesium hydroxide is a white, water-insoluble inorganic base used as a pH regulator in food processing and as a magnesium supplement. It is the active ingredient in milk of magnesia antacid preparations, reflecting its well-established safety and mild alkalinity. In food manufacturing it is used to adjust acidity in certain products and as a firming agent in some canned vegetable applications.

JECFA's ADI is "not specified," evaluated in 1965. Magnesium hydroxide is metabolised by reaction with stomach acid to produce magnesium chloride and water, providing bioavailable magnesium. At large supplemental doses it has a well-known laxative effect through osmotic action — the same mechanism used therapeutically — but at food additive concentrations this effect does not occur.

Magnesium hydroxide is approved in the EU, US (GRAS), UK, and globally. It is found in certain food processing applications and as a mineral supplement carrier. The magnesium contribution is nutritionally beneficial for most people. People with renal disease who must restrict magnesium should monitor intake, but for healthy adults there are no safety concerns from food additive use.