Summary Vitamin K may affect  bone mineral density and fracture incidence .
Since publication of a previous systematic review the integrity of some of the previous evidence has been question ed and further trials have been published .
Introduction This systematic review was design ed to assess the effectiveness of oral vitamin K supplementation for increasing bone mineral density  and reducing fractures in adults .
Vitamin K2 supplementation improves hip bone geometry and bone strength indices in postmenopausal women
Summary Vitamin K mediates the synthesis of proteins regulating bone metabolism . We have tested whether high vitamin K2 intake promotes bone mineral density and bone strength . Results showed that K2 improved BMC and femoral neck width , but not DXA-BMD . Hence high vitamin K2 intake may contribute to preventing postmenopausal bone loss . Introduction Vitamin K is involved in the synthesis of several proteins in bone . The importance of K vitamins for optimal bone health has been suggested by population -based studies , but intervention studies with DXA-BMD as a clinical endpoint have shown contradicting results . Unlike BMC , DXA-BMD does not take into account the geometry ( size , thickness ) of bone , which has an independent contribution to bone strength and fracture risk . Here we have tested whether BMC and femoral neck width are affected by high vitamin K intake . Methods A r and omized clinical intervention study among 325 postmenopausal women receiving either placebo or 45 mg/day of vitamin K2 ( MK-4 , menatetrenone ) during three years .  BMC and hip geometry were assessed by DXA . Bone strength indices were calculated from DXA-BMD , femoral neck width ( FNW ) and hip axis length ( HAL ) . Results K2 did not affect the DXA-BMD , but BMC and the FNW had increased relative to placebo . In the K2-treated group hip bone strength remained unchanged during the 3-year intervention period , whereas in the placebo group bone strength decreased significantly . Conclusions Vitamin K2 helps maintaining bone strength at the site of the femoral neck in postmenopausal women by improving BMC and FNW , whereas it has little effect on DXA-BMD
Summary Vitamin K may affect  bone mineral density and fracture incidence .
Since publication of a previous systematic review the integrity of some of the previous evidence has been question ed and further trials have been published .
Introduction This systematic review was design ed to assess the effectiveness of oral vitamin K supplementation for increasing bone mineral density  and reducing fractures in adults .