[Frontiers in vitamin D; basic Research and clinical application. Effect of active vitamin D3 on osteoporosis].

Although active vitamin D₃ only slightly increases bone mineral density (BMD) , it prevents fractures to a greater extent than is predicted, based on measurements of BMD. This effect is partly attributed to enhanced muscle strength and increased physical capabilities by vitamin D, which, in turn, decreases the risk of falls and fractures. In addition, active vitamin D₃ has been reported in animal studies to improve bone quality by enhancing trabecular bone microarchitecture and increasing enzymatic collagen cross-links in bone. A (large scale of) randomized controlled trial in Japanese postmenopausal women verified that the combination therapy of bisphosphonate (alendronate) plus active vitamin D₃ was more effective than monotherapy in terms of fracture prevention in high fracture risk group.