Vitamin D metabolism within bone cells: Effects on bone structure and strength

The endocrine activity of 1,25-dihydroxyvitamin D (1,25(OH)2D3) contributes to maintaining plasma calcium and phosphate homeostasis through actions on the intestine, kidney and bone. A significant body of evidence has been published over the last 10 years indicating that all major bone cells have the capacity to metabolise 25-hydroxyvitamin D (25(OH)D3) to 1,25(OH)2D3, which in turn exerts autocrine/paracrine actions to regulate bone cell proliferation and maturation as well as bone mineralisation and resorption. In vivo and in vitro studies indicate that these autocrine/paracrine activities of 1,25(OH)2D3 in bone tissue contribute to maintaining bone mineral homeostasis and enhancing skeletal health.