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 K supplementation does not significantly impact bone mineral density and biochemical markers of bone in pre- and perimenopausal women.
Because of its role in osteoblastic metabolism , vitamin K has been studied with respect to bone . However , there has been limited research examining the influence of long-term vitamin K supplementation on bone mineral density ( BMD ) . Therefore , the purpose of this study was to assess the impact of 6 months of vitamin K supplementation on BMD and biomarkers of bone in pre- and perimenopausal women . Based on previous work , we hypothesized that vitamin K would improve BMD and biochemical markers of bone formation . A double-blind , placebo-controlled , r and omized trial is an effective way to study the impact of long-term supplementation . Thus , 14 pre- and perimenopausal women , 25 to 50 years of age , were r and omly assigned to an experimental group ( E ) that received 600 microg/d of vitamin K in the form of phylloquinone ( K(1 ) ) or a control group ( C ) that received identical-looking placebo tablets .  Regional BMD and percent body fat , measured by dual-energy x-ray absorptiometry , and serum osteocalcin and urinary N-telopeptide levels were all assessed at 0 , 3 , and 6 months . When BMD was measured across time , C had a significant increase ( P = .011 ) in greater trochanter BMD compared to E. The E group had a nonsignificant increase ( P = .067 ) in shaft BMD compared to the C group . There was no significant difference between E and C in serum osteocalcin concentrations over time . Urinary N-telopeptide levels increased significantly over time in E compared to C ( P = .008 ) . Six months of 600 microg/d vitamin K(1 ) supplementation did not improve regional BMD in this group of pre- and perimenopausal women
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 .