The Association Between Serum Vitamin D Level and Nonalcoholic Fatty Liver Disease

Background: Nonalcoholic fatty liver disease (NAFLD) is a condition, in which triglyceride accumulates in hepatic cells without a history of alcohol consumption and is strongly associated with insulin resistance, obesity, diabetes mellitus, hypertension and dyslipidemia. The potential role of vitamin D in the pathogenesis of NAFLD has been reported. Objectives: The aim of this study was to determine the optimal vitamin D levels for prevention of NAFLD. Methods: In a cross-sectional study, 2,160 cases who referred to a university-affiliated health center were randomly selected and their demographic information, anthropometric and metabolic indices and also vitamin D levels were collected. Fatty liver was assessed by fatty liver index (FLI) and confirmed by FibroScan using controlled attenuation parameter (CAP). Based on the NAFLD score, the subjects were divided into two groups and the vitamin D cutoff point was calculated by ROC curve. Results: Based on the results, 745 patients (34.5%) had different degrees of fatty liver. Significant differences in the stiffness of liver tissue were observed between vitamin D categories (285.10 ± 30.56 for severe, 251.82 ± 42.63 for moderate and 201.02 ± 36.08for mild deficiency). According to the multivariate analysis, age, fasting insulin and vitamin D levels were found as the most significant factors in NAFLD pathogenesis. Vitamin D cutoff point was obtained 18 nmol/L in women and 21 nmol/L in men. Conclusions: The results indicated a significant association between vitamin D level and NAFLD score. Accordingly, increasing the public awareness to maintain a proper level of vitamin D may be a preventative strategy against NAFLD.