What factors affect calcium absorption into bone?
There is no doubt that calcium intake is essential to grow and maintain bone mass and that calcium supplements are important. However, there are a number of factors that affect calcium absorption into bone. Overall calcium absorption into bone will be affected by the quantity of elemental bone in the supplement, intestinal absorption (digestibility), loss from urinary excretion, and transport to bone and incorporation into bone matrix. For example, optimal absorption into bone requires vitamin D. In the absence of vitamin D, only 10 percent of dietary calcium is absorbed. Supplementation of vitamin D intake to provide 600-800 IU/day has been shown to improve calcium balance and reduce fractures. The inclusion of vitamin D in any calcium supplement is important.
