Most of the body's calcium is deposited in bones and teeth but it is also required by the nerves and muscles. It is a mineral that is daily lost from the body's reserves or lost to the body because of low absorption from food. During pregnancy the requirement for calcium is high because of the demands made by the developing foetus on the mother's supply. The high demand continues after birth as children need it for growth. It is a main part of the skeletal "frame" to which tissues and muscles are attached and which protects the vulnerable organs from physical harm. There are 206 bones in the body which together provide its structure, articulation and protection.

The rate of calcium depletion is much higher in older women and a regular dietary intake of calcium is important to help keep their reserves at optimum levels. Calcium is equally important for nerve impulse transmission and blood coagulation.