Aims: Vitamin K sufficiency has been linked to better musculoskeletal health. The majority of vitamin K intake comes from vegetables in the form of K1. We previously demonstrated an inverse association between intake of cruciferous vegetables, a good source of K1, and fracture-related hospitalisations (1). We aimed to examine the association of dietary K1 intake with bone structure and fracture-related hospitalisations over 14.5 years in the Perth Longitudinal Study of Ageing Women, a prospective cohort study of older Australian women (n=1429, ≥ 70 years).
Methods: Vitamin K1 intake at baseline (1998) was estimated using a validated food frequency questionnaire and the USDA National Nutrient Database. Hip and heel bone were measured using dual x-ray absorptiometry and quantitative ultrasonography (speed of sound [SOS] and broadband ultrasound attenuation [BUA]), respectively. Total fracture (n=404, 28.3%) and hip fracture (n=153, 10.7%) hospitalisations over 14.5 years were captured using linked health records.
Results: Kaplan-Meier curves for quartiles of vitamin K1 intake with any fracture and hip fracture-related hospitalisations are presented in Figure 1. In multivariable-adjusted Cox regression models, women with the highest vitamin K1 intake (Quartile 4, ≥118 ug/d) had lower hazards for any fracture (HR 0.55 95%CI 0.41-0.45, p<0.001) and hip-fracture related hospitalisation (HR 0.37 95%CI 0.21-0.65, p<0.001) compared to women with the lowest vitamin K1 intake (Quartile 1, <68 ug/d). Multivariable-adjusted generalised linear models showed women with the highest vitamin K1 intake had higher hip BMD (mean difference [MD] 0.033 95%CI 0.006-0.060, p=0.006) and faster SOS (MD 5.73 95%CI 0.35-11.10, p=0.030) compared to women with the lowest vitamin K1 intake.
Conclusion: These data identify a substantial reduction in fracture risk and beneficial effects on bone structure in those participants with high baseline intakes of vitamin K1.