Low plasma phylloquinone concentration is associated with high incidence of vertebral fracture in Japanese women

It has been reported that vitamin K supplementation effectively prevents fractures and sustains bone mineral density in osteoporosis. However, there are only limited reported data concerning the association between vitamin K nutritional status and bone mineral density (BMD) or fractures in Japan. The objectives were to evaluate the association between plasma phylloquinone (K ₁) or menaquinone (MK-4 and MK-7) concentration and BMD or fracture in Japanese women prospectively. A total of 379 healthy women aged 30-88 years (mean age, 63.0 years) were consecutively enrolled. Plasma K₁, MK-4, MK-7, and serum undercarboxylated osteocalcin (ucOC) concentrations, BMD, and incidence of vertebral fractures were evaluated. In stepwise multiple linear regression analyses, L_2-4 BMD and a bone turnover marker, log K ₁, concentrations were independently correlated with vertebral fracture incidence. When subjects were divided into low and high K₁ groups by plasma K₁ concentration, the incidence of vertebral fracture in the low K₁ group (14.4%) was significantly higher than that in the high K₁ group (4.2%), and its age-adjusted RR was 3.58 (95% CI, 3.26-3.93). L_2-4 BMD was not different between the two groups. These results suggest that subjects with vitamin K₁ insufficiency in bone have increased susceptibility for vertebral fracture independently from BMD.