Positive Association Between Serum 25-Hydroxy-Vitamin D and Liver Enzymes Levels in Healthy Individuals: A Population-Based Study from Iran

Objective: The relationship between serum 25-hydroxy-vitamin D and within normal range liver enzymes in a population-based study in the northwest of Iran was investigated. Method: This cross-sectional study was comprised of 700 apparently healthy Iranian adults (287 men & 413 women) who participated in the major lifestyle promotion project (LPP) conducted in East Azarbaijan-Iran in 2015. The ultraviolet method and chemiluminescent immunoassay technology were respectively used for determination of the serum levels of liver enzymes (alanine aminotransferase (ALT) and aspartate aminotransferase (AST)) and 25-hydroxy-vitamin D. The one-way ANOVA and the linear regression analysis were used for statistical analysis. Results: There were not significant differences in mean ALT and AST levels regarding different serum 25-hydroxy- vitamin D status. In the unadjusted model, serum 25-hydroxy-vitamin D was significantly associated with ALT (p = 0.008). The participants in the fourth quartile of 25-hydroxy-vitamin D had significantly higher level of ALT compared with participants in the first quartile (p = 0.002). After adjustment for age, sex, BMI, waist circumference, fasting blood glucose, lipid profile, and dietary vitamin D, this association remained significant. For AST, in the unadjusted model, the association between serum 25-hydroxy-vitamin D and AST was marginally significant (p = 0.08). The participants in the third quartile of 25-hydroxy-vitamin D had significantly higher levels of AST compared with participants in the first quartile (p = 0.01). Conclusion: According to results, there was a positive association between 25-hydroxy-vitamin D and ALT in individuals without liver diseases. Additional prospective studies were needed to confirm this observation and also elucidate the underlying mechanisms.