This systematic review suggests that supplementation with phytonadione and menaquinone-4 reduces bone loss .
In the case of the latter , there is a strong effect on incident fractures among Japanese patients
BACKGROUND Observational and some experimental data suggest that low intake of vitamin K may be associated with an increased risk of fracture .
OBJECTIVE To assess whether oral vitamin K ( phytonadione and menaquinone ) supplementation can reduce  bone loss  and prevent fractures .
Vitamin K2 inhibits glucocorticoid-induced bone loss partly by preventing the reduction of osteoprotegerin (OPG)
We have recently demonstrated that glucocorticoid ( GC ) suppresses bone formation and enhances bone resorption , with result ant bone loss . This altered bone turnover is not due to the action of parathyroid hormone ( PTH ) , but appears to be related to the suppression of osteoprotegerin ( OPG ) . As vitamin K2 ( menatetrenone ) has been used for the treatment of osteoporosis , the present study was carried out to evaluate the effect of vitamin K2 on GC-induced bone loss . Twenty patients with chronic glomerulonephritis treated with GC for the first time were chosen for this study . Ten patients received GC alone  ( group A ) and the other 10 patients each received 15 mg of vitamin K2 per day in addition to GC ( group B ) . Markers of bone metabolism , including serum OPG , osteocalcin ( OC ) , bone-specific alkaline phosphatase activity ( BAP ) , PTH , tartrate-resistant acid phosphatase ( TRAP ) , and bone mineral density ( BMD ) , were measured before and during the treatment . OPG was significantly decreased in group A ( P < 0.001 ) , while no significant change was seen in group B. TRAP was markedly increased in both groups , more particularly in group A ( P < 0.01 ) . PTH was decreased in group A , but was increased in group B. OC was decreased at month 1 but subsequently increased until month 12 in both groups . BAP had decreased at month 3 in group A ( P < 0.05 ) , but not in group B. BMD of the lumbar spine was significantly reduced after 6 months ( P < 0.01 ) , and 12 months ( P < 0.001 ) of treatment in group A , whereas there was no remarkable change in group B. The present study demonstrated that the inhibition exerted by vitamin K2 of the reduction in OPG induced by GC may , at least in part , play a role in the prevention and treatment of GC-induced  bone loss
This systematic review suggests that supplementation with phytonadione and menaquinone-4 reduces bone loss .
In the case of the latter , there is a strong effect on incident fractures among Japanese patients
BACKGROUND Observational and some experimental data suggest that low intake of vitamin K may be associated with an increased risk of fracture .
OBJECTIVE To assess whether oral vitamin K ( phytonadione and menaquinone ) supplementation can reduce  bone loss  and prevent fractures .