Higher vitamin K1 intakes are associated with lower subclinical atherosclerosis and lower risk for atherosclerotic vascular disease-related outcomes in older women.

PURPOSE

Vitamin K may inhibit vascular calcification, a common attribute of atherosclerotic vascular diseases (ASVDs). We examined associations between dietary vitamin K1 intakes and both subclinical atherosclerosis and ASVD events, including hospitalisations and mortality, in older women.

METHODS

1,436 community-dwelling women (mean ± SD age 75.1 ± 2.7 years) were included. Vitamin K1 intakes were calculated from a validated food frequency questionnaire at baseline (1998), utilising a region-matched vitamin K food database. Common carotid artery intima-media thickness (CCA-IMT), a measure of subclinical atherosclerosis, was measured in 2001 (n = 1,090). Differences in CCA-IMT by quartiles (Q) of vitamin K1 intake were examined using multivariate analysis of variance. Associations between vitamin K1 intakes and ASVD outcomes (hospitalisations and/or deaths), obtained from linked health records over 14.5 years, were analysed using restricted cubic splines within multivariable-adjusted Cox-proportional hazard models.

RESULTS

Women with higher vitamin K1 intakes had a 5.6% lower mean CCA-IMT (Q4 [median 119 µg/day] compared to Q1 [median 49 µg/day], p < 0.001). Over 14.5 years, 620 (43.1%), 497 (34.6%) and 301 (20.9%) ASVD events, hospitalisations, and deaths were recorded, respectively. In multivariable-adjusted models, the highest vitamin K1 intakes (Q4, compared to Q1), were associated with lower relative hazards for ASVD events (HR 0.71 95%CI 0.55-0.92) and ASVD mortality (HR 0.57 95%CI 0.40-0.83), but not ASVD hospitalisations (HR 0.83 95%CI 0.63-1.11).

CONCLUSION

Vitamin K1 intakes of ~ 120 µg/day appear to be beneficial in lowering risk for subclinical and clinical ASVD in older women. These quantities can be attained by consuming vitamin K1 rich foods, such as leafy green vegetables.