Vitamin D, bone metabolism and fracture risk
Thierry Thomas1, Karine Briot2
1Service de rhumatologie, Inserm U1059, CHU de Saint-Étienne, France.
Abstract:
Insufficient serum levels of 25OH vitamin D (25OHD) is a risk factor for osteoporosis. A new paradigm has emerged with the locally synthesized 1,25(OH)2D within osteoblasts and osteoclasts as the essential pathway for the effects of 25OHD in regulating bone remodeling via direct or indirect activation of the specific receptor VDR. Vitamin D has positive effects on fracture risk but these results have been consistently observed whenever daily doses were above 800 UI/d administered to compliant patients together with adequate calcium supplementation and with an achieved biological target of serum 25OHD levels above 30 ng/mL.
Related Concept Videos
Role of Vitamins in Maintaining Bone Health
Vitamin A
Vitamin A is involved in the process of bone remodeling. Retinoic acid, the active metabolite of Vitamin A, has nuclear receptors in osteoblasts and osteoclasts, which are involved in bone remodeling.
Vitamin B12
Vitamin B12 acts as a cofactor during the formation of osteoblast-related proteins, such as osteocalcin. Vitamin B12 plays a role...
Bone Disorders
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
Skeleton and Calcium Homeostasis
Essential Minerals for Bone Health
Calcium and Phosphorus
Calcium is a critical component of bones, especially in the form of calcium phosphate and calcium carbonate. Since the body cannot make calcium, it must be obtained from the diet. However, calcium cannot be absorbed from the small intestine without...
Bone Remodeling
Role of Skin in Vitamin D Synthesis
The solar UV B rays (290-315 nm) are absorbed by the skin, and 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin...


