Dietary vitamin K intake associates with reduced all-cause mortality in non-alcoholic fatty liver disease patients

This study aimed to investigate the association between dietary vitamin K intake and all-cause mortality in individuals with non-alcoholic fatty liver disease (NAFLD). We analyzed data from 7857 NAFLD participants in the National Health and Nutrition Examination Survey (NHANES 2005-2018) linked to mortality outcomes from the National Death Index (NDI). Dietary vitamin K intake was log-transformed (ln[VK]) for analysis. Multivariable Cox proportional hazards models and restricted cubic splines were used to evaluate dose-response relationships. Sensitivity analyses, subgroup analyses, and receiver operating characteristic (ROC) curves were performed to validate findings. Over 180 months of follow-up, 842 deaths occurred. Higher ln[VK] was associated with reduced mortality risk, demonstrating an adjusted hazard ratio (HR) of 0.81 per 1-unit increasement (95% confidence interval CI 0.67-0.98, P-trend = 0.028). Restricted cubic splines revealed a U-shaped relationship (P-nonlinear = 0.0009), with an optimal threshold at 121 mu g/day (ln[VK] = 4.71). Below this threshold, each unit increase in ln[VK] corresponded to a 33% lower mortality risk (HR = 0.67; 95% CI 0.55-0.81), whereas no significant association was observed above it (HR 1.07; 95% CI 0.67-1.71). The fully adjusted prediction model showed robust discriminative ability, with an area under the curve (AUC) of 0.832. Results remained consistent across sensitivity analyses. Moderate dietary vitamin K intake (up to 121 mu g/day) is associated with reduced all-cause mortality in NAFLD patients, with a threshold effect informing tailored dietary recommendations. This study provides novel evidence for optimizing vitamin K intake in NAFLD management.