While current intakes of
phylloquinone (
vitamin K1) in many populations are believed to be sufficient to maintain normal blood coagulation, these may be insufficient to cover the requirements for optimal bone metabolism. Therefore, the objective of the present study was to investigate the effect of increasing
phylloquinone intakes above the usual dietary intake for 6 weeks on
biochemical markers of
vitamin K status and bone turnover in postmenopausal women. Thirty-one postmenopausal women completed this 3 x 6-week randomised cross-over study, in which volunteers were supplemented with 0 (placebo), 200, and 500 microg
phylloquinone/d. In addition, the volunteers were given 10 microg
vitamin D3/d throughout the study period. With increasing
phylloquinone intake, the concentration of serum gamma-carboxylated and under-gamma-carboxylated
osteocalcin was significantly increased and decreased, respectively, in a dose-dependent manner (P < 0.001). Mean serum
phylloquinone concentration was significantly (P < 0.001) higher with daily supplementation with 500 microg
phylloquinone/d compared with that during either of the placebo or 200 microg
phylloquinone/d supplementation periods, which did not differ (P = 0.15). Serum total
osteocalcin was significantly (P < 0.001) increased in response to daily supplementation with 500 (but not 200) microg
phylloquinone compared with placebo. Serum bone-specific
alkaline phosphatase as well as the urinary markers of
bone resorption (
N-telopeptide cross-links of
collagen,
pyridinoline and
deoxypyridinoline) and urinary
gamma-carboxyglutamate were unaffected by
phylloquinone supplementation. In conclusion, while daily supplementation with 200 and 500 microg
phylloquinone/d for 6 weeks increased
vitamin K status in postmenopausal women, it had no effect on bone turnover.