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 .
Effect of vitamin K on vascular health and physical function in older people with vascular disease–a randomised controlled trial
Background and Aims Vitamin K insufficiency is common and linked to an increased risk of cardiovascular disease and osteoporotic fractures . The aim of this study was to examine whether daily supplementation with oral vitamin K could improve vascular health and physical function in older people with established vascular disease . Methods and results A double blind , r and omised , placebo-controlled trial . Participants aged ≤ 70 years with a history of vascular disease were r and omised to receive 6 months of daily oral 100mcg vitamin K2 ( MK7 subtype ) or matching placebo with outcomes measured at 0 , 3 and 6 months . The primary outcome was between-group difference in endothelial function assessed using flow-mediated dilatation of the brachial artery at 6 months . Secondary outcomes included carotid-radial pulse wave velocity , augmentation index , blood pressure , carotid intima-media thickness , C-reactive protein , B-type natriuretic peptide , cholesterol and desphospho-uncarboxylated matrix Gla protein levels . H and grip strength and the Short Physical Performance Battery assessed physical function , while postural sway was measured using a 3-dimensional force platform . Results 80 participants were r and omised , mean age 77 ( SD 5 ) years ; 44/80 were male .  Vitamin K levels rose in the intervention arm compared to placebo ( + 48 pg/ml vs −6 pg/ml , p=0.03 ) at 6 months . Desphospho-uncarboxylated Matrix Gla protein levels fell in the intervention group compared to placebo at 6 months ( −130 [ SD 117 ] pmol/L vs + 13 [ SD 180 ] pmol/L , p<0.001 ) . No change was seen in endothelial function ( between group difference −0.3 % [ 95%CI −1.3 to 0.8 ] , p=0.62 ) . A modest , non-significant improvement in pulse wave velocity was seen in the vitamin K group ( −0.8 m/s [ 95%CI −1.8 to 0.3 ] , p=0.15 ) while all other vascular and physical function outcomes unchanged . Conclusions Six months of vitamin K2 supplementation did not improve markers of vascular health or physical function in older patients with vascular disease
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 .