Calcium is the most plentiful mineral found in the human body, accounting for 1.5% to 2% of an adult's total body weight. The teeth and the bones contain the majority of the body's calcium (about 99%). Calcium in these tissues is concentrated in the form of calcium phosphate salts. Nerve cells, body tissues, blood, and other body fluids contain the remaining calcium.

Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human body. Calcium is essential for the formation of and maintenance of healthy teeth and bones. The bones incorporate calcium into their structure. Like other tissues in the body, bones are continually being reabsorbed and re-formed. Teeth incorporate calcium in their structure in a manner similar to bones. Calcium has other functions in addition to maintaining healthy teeth and bones. Blood coagulation, transmission of nerve impulses, muscle contraction and relaxation, normal heartbeat, stimulation of hormone secretion, activation of enzyme reactions, as well as other functions all require small amounts of calcium.

Many foods contain calcium, but dairy products are the most significant source. Milk and dairy products such as yogurt, cheeses, and buttermilk contain an efficiently absorbed form of calcium.