Low vitamin K status ups risk of all-cause mortality

Low concentrations of circulating phylloquinone (vitamin K) appears to increase the risk of all-cause mortality, but not cardiovascular disease (CVD), suggests a recent study.

Individual participant-level data were obtained from the Health, Aging, and Body Composition Study, the Multi-Ethnic Study of Atherosclerosis, and the Framingham Offspring Study, known cohorts with available measures of fasting circulating phylloquinone and confirmed CVD events and mortality.

The authors measured circulating phylloquinone in a central laboratory from fasting blood samples and categorized vitamin K concentrations as ≤0.5 nmol/L, >0.5–1.0 nmol/L, and >1.0 nmol/L. They used multivariable Cox proportional hazard regression with multiple imputations to assess the association of circulating phylloquinone with incident CVD and all-cause mortality risk.

A total of 3,891 participants (mean age, 65 years; 55 percent women; 35 percent nonwhite) were included in the analysis. Over a median follow-up of 13.0 years, 858 incident CVD events and 1,209 deaths were recorded among these individuals.

No significant difference in CVD risk was found as per circulating vitamin K: ≤0.5 nmol/L (fully adjusted hazard ratio [aHR], 1.12, 95 percent confidence interval [CI], 0.94–1.33); >0.5–1.0 nmol/L (aHR, 1.02, 95 percent CI, 0.86–1.20).

However, participants with ≤0.5 nmol/L circulating phylloquinone had a 19-percent higher risk of all-cause mortality than those with >1.0 nmol/L (aHR, 1.19, 95 percent CI, 1.03–1.38). Of note, mortality risk was similar between participants with >0.5–1.0 and >1.0 nmol/L (aHR, 1.04, 95 percent CI, 0.92–1.17).

“Additional studies are needed to clarify the mechanism underlying this association and evaluate the impact of increased phylloquinone intake on cardiovascular and other health outcomes in individuals with low vitamin K status,” the authors said.