Abstract
Recent studies have suggested that vitamin K deficiency influences not only blood coagulation system but also bone metabolism. To prevent fracture, higher vitamin K intake may be required than to maintain the blood coagulation system. Currently, among vitamin K_2 homologues, MK-4 is used to treat osteoporosis in clinical practice. It has been reported that MK-4 inhibits bone resorption, and promotes bone formation in in vitro systems. In animal experiments, the results of histological evaluation also supported the above findings. Furthermore, the effects of MK-4 on bone mineral content (BMC) and bone strength were compared using several animal models. As a result, MK-4 not only improved bone strength in response to BMC, but also improved bone strength without affecting BMC in some models. In a clinical study, it has been reported that MK-4 is more effective for reducing the incidence of fracture than for improving bone mineral density These results suggest that MK-4 may improve bone quality.