The adult human body contains approximately 1,200 grams of calcium, about 99% of which is present in the skeleton, and 20-30 grams of magnesium of which 60% is located in bone. Bone is constantly turned over and is a source of calcium when serum calcium falls. Supplementation has been shown to offset the calcium depleting affects of a high intake of sodium and caffeine commonly seen in the North American diet.
Calcium absorption is dependent on ionization in the intestine. Insufficient stomach acid can reduce calcium absorption to as low as four percent. Calcium bound to Kreb cycle intermediates, such as citrate, are the most absorbable forms of calcium and therefore provide greater benefit than other sources. Calcium citrate in a 2:1 ratio with magnesium has been shown to be one of the most bioavailable forms of calcium delivery to the body.
Vitamin D plays a role in calcium and bone metabolism. Adequate vitamin D status is essential for ensuring normal calcium absorption and maintenance of calcium plasma levels. Furthermore, calcium intake when combined with vitamin D, a healthy diet and regular exercise may reduce the risk of developing osteoporosis.
Magnesium is essential for the development and maintenance of bones and teeth and helps ensure proper muscle function.