Magnesium oxide

Magnesium oxide is a fine white powder derived from the calcination of magnesium carbonate or hydroxide. In food it functions primarily as an anti-caking agent, preventing clumping in powdered products such as table salt, spice blends, cocoa powder, and powdered milk. It also serves as a pH regulator in certain food systems and is used as a magnesium dietary supplement given its high magnesium content by weight.

JECFA's ADI is "not specified," evaluated in 1965. Magnesium oxide is partially soluble in water, releasing magnesium ions in the gut. The bioavailability of magnesium from magnesium oxide is lower than from magnesium citrate or glycinate forms, but it still contributes to dietary magnesium. No adverse effects have been identified at any realistic dietary exposure from food additive use.

Magnesium oxide is approved in the EU, US (GRAS), UK, and globally. It is found in table salt, powdered foods, and certain health food products. For the general population there are no safety concerns. Magnesium is an essential mineral involved in hundreds of enzymatic reactions, and E530 contributes to total dietary magnesium intake from food. People with renal disease managing magnesium intake should be aware of its use.