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 .
Serum undercarboxylated osteocalcin correlates with hip bone mineral density in elderly women.
We previously showed that circulating undercarboxylated osteocalcin  ( ucOC ) is elevated in elderly women and is a powerful marker of the subsequent risk of hip fracture in elderly institutionalized women ( J Clin Invest 1993 ; 91:1769 ) . To investigate the relationship between bone mass and ucOC , we measured bone mineral density ( BMD ) of the hip with dual-energy x-ray absorptiometry in 98 elderly institutionalized women , 81.4 + /- 6.0 years old .  ucOC was negatively correlated with BMD at all sites ( r = -0.26 to -0.38 , p < 0.001 to p < 0.0001 ) , even after exclusion of the effect of age by partial correlation ( for the femoral neck , r = -0.26 , p < 0.01 ) and after controlling for serum parathyroid hormone . BMD was significantly lower at all sites of measurement in women with elevated ucOC ( > 1.65 ng/ml , upper limit of the normal range in young women ) than in those with normal ucOC ( for the neck , 0.58 + /- 0.13 versus 0.43 + /- 0.13 g/cm2 , p < 0.001 ) . Similar results were obtained for ucOC expressed as the fraction of total OC ( ucOC% ) . Multiple regression showed that ucOC has the highest predictive value for BMD when including age and body weight in the equation . In summary , our data indicate that serum ucOC is an independent determinant of BMD of the hip in elderly women . The mechanism by which serum ucOC is related to bone mass is unclear and should be addressed in further studies . However , our data suggest that ucOC level may be an interesting marker in the investigation of bone status in the elderly
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 .