Magnesium is the eleventh most plentiful element by mass in the human body. Its ions are necessary to all cells. They interrelate with polyphosphate compounds such as ATP, DNA, and RNA. Hundreds of enzymes need magnesium ions to function. Magnesium compounds are used medicinally as general laxatives, antacids and to stabilize abnormal nerve excitation or blood vessel spasm such as in eclampsia.