Temporal trend of serum vitamin profiles and the association with non-alcoholic fatty liver disease

Background Few studies have simultaneously examined temporal trends in multiple serum vitamins and their associations with non-alcoholic fatty liver disease (NAFLD), especially in non-Western populations. This study aimed to characterize temporal trends of serum vitamins (A, B9, B12, D, E) among Chinese adults undergoing health examinations (2015–2023) and explore their associations with NAFLD. Methods Subjects were extracted from the electronic health records of the Department of Health Management, the First Affiliated Hospital of Army Medical University. Vitamin levels were quantified via electrochemical methods. NAFLD was diagnosed using abdominal ultrasound. Mean vitamin levels and 95% confidence intervals (CIs) were calculated and compared across 9 years overall and in subgroups (age, sex, BMI, and NAFLD status). Odds ratios (ORs) and 95% CIs for the associations between vitamin quintile groups and NAFLD risk were assessed by logistic regression. Dose-response relationships were explored using the restricted cubic spline (RCS) approach. Joint effects of vitamins B9 and B12 were also evaluated. Results 75,401 adults with complete data on vitamins were included. Serum vitamins A, B9, B12, 25(OH)D, and E changed annually by −0.007, −0.223, −4.043, −0.577, and −0.075 (all P trend 0.05). Stratified analyses revealed the lowest serum vitamin levels among women, individuals aged ≥60 years, and those with overweight/obesity or NAFLD. 67,356 (27.515% NAFLD) eligible participants were used for association analysis. Lower vitamin levels were associated with an increased NAFLD risk. The RCS curves indicated non-linear relationships between each vitamin and NAFLD status (All P non − linear 0.001). Higher vitamins B9 and B12 levels may correlate with lower NAFLD prevalence. Conclusion Our findings indicated a downward trend of serum vitamins A, B9, B12, D, and E during the 9-year period among Chinese health examination adults, especially among senior women.