[Vitamin K and fracture].

Vitamin K is well known for its role in the synthesis of a number of blood coagulation factors. Vitamin K is also an important factor for bone metabolism via gamma-carboxylation of vitamin K-dependent proteins such as osteocalcin, matrix Gla protein, and protein S. Recent studies suggest that there is potential vitamin K insufficiency in bone, even in sufficient vitamin K status for blood coagulation. In the present review, the studies concerning relationship between vitamin K status and fracture are reviewed.