Background: Polymorphisms in the apolipoprotein E (APOE) gene are associated with fracture risk, and a potential mechanism is through vitamin K transport.
Objective: We investigated the relation between dietary vitamin K(1) intake, APOE polymorphisms, and markers of bone health.
Design: We measured bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN) in a cohort of Scottish women aged 49-54 y in 1990-1994 (baseline) and in 1997-2000 (visit 2). At visit 2, bone markers (urinary pyridinoline crosslinks and serum N-terminal propeptide of type 1 collagen) were measured, 3199 women completed a food-frequency questionnaire, and 2721 women were genotyped for APOE.
Results: Compared with quartile 3 (Q3) of energy-adjusted vitamin K(1) intake (mean: 116 microg/d), women in the lowest quartile (mean: 59 microg/d) had lower BMD (analysis of variance; FN, Q1: 0.831 +/- 0.122 g/cm(2); Q3: 0.850 +/- 0.126 g/cm(2); P < 0.001; LS, Q1: 1.000 +/- 0.170 g/cm(2); Q3: 1.020 +/- 0.172 g/cm(2); P = 0.009), remaining significant at the FN after adjustment for age, weight, height, menopausal status or use of hormone replacement therapy, socioeconomic status, and physical activity (P = 0.04). Vitamin K(1) intake was associated with reduced concentrations of pyridinoline crosslinks (Q1: 5.4 +/- 2.0 nmol/mmol; Q4: 5.1 +/- 1.9 nmol/mmol; P = 0.003). Carriers of the E2 allele had greater LS BMD at visit 2 and lost less BMD than did carriers of the E4 allele (E2: -0.50 +/- 1.22%/y; E4: -0.71 +/- 1.17%/y; P = 0.05). After adjustment for confounders, the P value for BMD loss (0.03 for LS and 0.04 for FN) did not reach the level of significance required for multiple testing (P = 0.012). No interaction was observed between dietary vitamin K and APOE on BMD.
Conclusions: Vitamin K(1) intake was associated with markers of bone health, but no interaction was observed with APOE alleles on BMD or markers of bone turnover.