Magnesium is the fourth most abundant mineral in the body. About 60% are found in the bones and teeth; 28% is in the muscles, liver and other soft tissues; and 2% is in the body fluids. It is essential to building bones and teeth and numerous metabolic functions. Magnesium is also an ingredient in some antacids and laxatives and is used to prevent premature birth and treat certain types of convulsions and rapid heartbeats (tachycardia). Recent research indicates that magnesium deficiency may be a factor in the development of atherosclerosis and coronary artery disease-the major cause of heart attacks.