High serum vitamin D levels reduce the risk for nonalcoholic fatty liver disease in healthy men independent of metabolic syndrome

Recent studies suggest an association of vitamin D with obesity, diabetes and cardiovascular diseases. We analyzed the association of serum vitamin D level assessed by 25-hydroxyvitamin D-3 {25(OH)D-3} with nonalcoholic fatty liver disease (NAFLD) in apparently healthy men. We performed a cross-sectional study of 6,567 Korean men who participated in a health screening program, evaluating the association of serum 25(OH)D-3 levels with the risk of NAFLD assessed by abdominal ultrasonogram. Of the participants, 43.6% had NAFLD and 21.1% had metabolic syndrome. Age, serum calcium, and aspartate aminotransferase levels showed weak but significant positive correlations with 25(OH)D-3 level; total cholesterol, triglycerides, low-density lipoprotein cholesterol and fasting insulin level showed weak but significant negative correlations with 25(OH)D-3 level. The mean 25(OH)D-3 level was significantly lower in participants with NAFLD than in those without (38.7 +/- 9.0 vs. 39.7 +/- 9.7 nmol/L, p < 0.001). When participants were divided into tertiles based on mean 25(OH)D-3 level, the proportion with NAFLD significantly increased as mean 25(OH)D-3 level decreased (40.0, 45.0 and 45.9%, p for linear trend < 0.001). Multiple logistic regression analyses with NAFLD as the dependent variable showed that the tertiles with lower 25(OH)D-3 levels had a significantly increased risk for NAFLD compared with the highest tertile, even after adjusting for body mass index and metabolic syndrome (OR 1.247 and 1.408 vs. the highest tertile, p < 0.001). Thus, participants with higher serum 25(OH)D-3 showed a significantly reduced risk for NAFLD compared with the low 25(OH)D-3 groups, independent of obesity and metabolic syndrome.