Calcium

Calcium is an essential mineral with a wide range of biological roles. The main function of calcium is the structural development and maintenance of healthy bones and teeth. Apart form being a major constituent of bones and teeth, calcium is essential for muscle contraction, nerve conduction, the beating of the heart, blood coagulation, glandular secretion, the production of energy and the maintenance of immune functioning.

Calcium is the most abundant mineral in the human body. Average healthy males contain about 2.5 to 3 pounds of calcium while females contain about 2 pounds. Approximately 99 percent of calcium is present in the bones and teeth, which leaves only about one percent in cells and body fluids.

Although only a small amount of calcium is in the blood, the body goes to great lengths to maintain blood-calcium levels within a relatively narrow range. Three regulatory mechanisms control blood-calcium. If levels drop too low, intestinal calcium absorption can increase, calcium can be released from bones and/or the kidneys can reduce calcium excretion. In bones and teeth, calcium exists primarily as hydroxyapatite, which is a calcium carbonate/calcium phosphate crystalline compound that provides rigidity and strength to these tissues.