Hypovitaminosis D is associated with increased whole body fat mass and greater severity of non‐alcoholic fatty liver disease

Abstract

Hypovitaminosis D is common in obesity and insulin-resistant states. Increased fat mass in patients with non-alcoholic fatty liver disease (NAFLD) may contribute to hypovitaminosis D. To determine the relation among plasma vitamin D concentration, severity of disease and body composition in NAFLD. Plasma vitamin D concentration was quantified in 148 consecutive biopsy-proven patients with NAFLD (non-alcoholic steatohepatitis - NASH: n=81; and hepatic steatosis: n=67) and healthy controls (n=39). NAFLD was scored using the NASH CRN criteria. Body composition was quantified by bioelectrical impedance analysis and abdominal CT image analysis. Plasma vitamin D concentration was significantly lower in NAFLD (21.2±10.4ng/ml) compared with healthy controls (35.7±6.0ng/ml). Higher NAFLD activity scores were associated with lower plasma concentration of vitamin D (r(2) =0.29; P<0.001). Subgroup analysis among patients with NAFLD showed that patients with NASH had significantly lower (P<0.01) vitamin D levels than those with steatosis alone (18.1±8.4 vs. 25.0±11.3ng/ml). Low concentrations of vitamin D were associated with greater severity of steatosis, hepatocyte ballooning and fibrosis (P<0.05).On multivariate regression analysis, only severity of hepatocyte ballooning was independently associated (P=0.02) with low vitamin D concentrations. Plasma vitamin D (P=0.004) and insulin concentrations (P=0.03) were independent predictors of the NAFLD activity score on biopsy. Patients with NAFLD had higher fat mass that correlated with low vitamin D (r(2) =0.26; P=0.008). Low plasma vitamin D concentration is an independent predictor of the severity of NAFLD. Further prospective studies demonstrating the impact of vitamin D replacement in NAFLD patients are required.