Magnesia, << mag NEE shuh or mag NEE zhuh, >> is a white, tasteless substance. It is a chemical compound made up of magnesium and oxygen and is also called magnesium oxide. A form of magnesia is used in medicines to aid digestion. Manufacturers also use magnesia in refining metals from their ores and in making crucibles, insulating material, and special cements.
After magnesia is swallowed, it is converted by water in the digestive system to magnesium hydroxide. Magnesium hydroxide is a good antacid because it neutralizes excess stomach acid without releasing carbon dioxide. This property also makes it a good antidote against poisoning by acids. In acid poisoning, a build-up of gas in the stomach may cause a rupture. Doctors may also recommend milk of magnesia, a mixture of water and magnesium hydroxide, as a laxative.
