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 treatment reduces undercarboxylated osteocalcin but does not alter bone turnover, density, or geometry in healthy postmenopausal North American women.
Low vitamin K status is associated with low BMD and increased fracture risk . Additionally , a specific menaquinone , menatetrenone ( MK4 ) , may reduce fracture risk . However , whether vitamin K plays a role in the skeletal health of North American women remains unclear . Moreover , various K vitamers ( e.g. , phylloquinone and MK4 ) may have differing skeletal effects . The objective of this study was to evaluate the impact of phylloquinone or MK4 treatment on markers of skeletal turnover and BMD in nonosteoporotic , postmenopausal , North American women . In this double-blind , placebo-controlled study , 381 postmenopausal women received phylloquinone  ( 1 mg daily ) , MK4 ( 45 mg daily ) , or placebo for 12 mo . All participants received daily calcium and vitamin D(3 ) supplementation . Serum bone-specific alkaline phosphatase ( BSALP ) and n-telopeptide of type 1 collagen ( NTX ) were measured at baseline and 1 , 3 , 6 , and 12 mo . Lumbar spine and proximal femur BMD and proximal femur geometry were measured by DXA at baseline and 6 and 12 mo . At baseline , the three treatment groups did not differ in demographics or study endpoints . Compliance with calcium , phylloquinone , and MK4  treatment was 93 % , 93 % , and 87 % , respectively . Phylloquinone and MK4 treatment reduced serum undercarboxylated osteocalcin but did not alter BSALP or NTX . No effect of phylloquinone or MK4 on lumbar spine or proximal femur BMD or proximal femur geometric parameters was observed . This study does not support a role for vitamin K supplementation in osteoporosis prevention among healthy , postmenopausal , North American women receiving calcium and vitamin D supplementation
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 .