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 .
Short-term menatetrenone therapy increases gamma-carboxylation of osteocalcin with a moderate increase of bone turnover in postmenopausal osteoporosis: a randomized prospective study
The effect of vitamin K2 ( menatetrenone ) on bone turnover was investigated in postmenopausal patients with osteoporosis . A 6-month open-label , r and omized prospect i ve study was conducted in 109 patients . The control group ( n = 53 ) received calcium aspartate ( 133.8 mg of elemental calcium daily ) , while the menatetrenone group ( n = 56 ) received 45 mg of menatetrenone daily for 6 months . Serum and urinary levels of bone turnover markers were monitored . The serum level of undercarboxylated osteocalcin ( uc-OC ) was significantly lower ( P < 0.001 ) in the menatetrenone group than in the control group ( at 1 month ) , while there was a higher level of osteocalcin containing gamma-carboxylated glutamic acid ( Gla-OC ) in the menatetrenone group than the control group ( P = 0.018 ) . Significant differences of uc-OC and Gla-OC between the two groups were observed from 1 month onward . In addition , a higher level of intact osteocalcin was found in the menatetrenone group compared with the control group after 6 months ( P = 0.006 ) . Assessment of bone resorption markers showed that menatetrenone therapy was associated with significantly higher urinary N-telopeptide of type I collagen ( NTX ) excretion compared with the control group after 6 months , while there was no significant difference of urinary deoxypyridinoline excretion between the two groups . In conclusion , one month of menatetrenone therapy enhanced the secretion and gamma-carboxylation of osteocalcin , while urinary NTX excretion was increased after 6 months of treatment . Further investigations are required to determine whether the effects of menatetrenone on bone turnover are associated with fracture prevention
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 .