Serum folic acid levels are associated with the presence and severity of liver steatosis in Chinese adults

Background & aims: Non-alcoholic fatty liver disease (NAFLD) is a common and strong risk factor for cardiovascular disease and hepatocellular carcinoma. The rapid acceleration of the increase in NAFLD prevalence has exceeded the trends observed for obesity, and has been driven by multiple factors. The aim of this study was to investigate the correlation between the serum levels of folic acid, the endogenous source of methyl groups for DNA methylation, and NAFLD in Chinese adults. Methods: The correlations between the serum folic acid levels and NAFLD were investigated in two independent cohorts of 70 subjects who underwent a liver biopsy and 130 subjects with varying liver fat contents, as measured using proton magnetic resonance spectroscopy (H-1-MRS). Independent correlations between serum folic acid levels and liver steatosis grades were detected using a multivariate ordinal regression analysis. The diagnostic performances of serum folic acid levels alone and in combination with existing NAFLD prediction scores were compared with those of traditional NAFLD prediction parameters using receiver operating characteristic (ROC) curve analyses. Results: Serum folic acid concentrations were inversely correlated with liver histological steatosis grades (p = -0.371, P < 0.001) and the H-1-MRS-measured liver fat content (r = -0.199, P = 0.038). According to the multivariate ordinal regression analysis, serum folic acid levels were inversely correlated with liver steatosis grades (OR 0.739 [0.594-0.918], P = 0.006) independent of age, gender, BMI, components of metabolic syndrome and the serum TC, LDL-c and HOMA-IR levels. The AUROC of serum folic acid for the diagnosis of NAFLD was 0.75 (0.65-0.83), and the addition of serum folic acid to NAFLD prediction scores significantly improved the diagnostic prediction of NAFLD (AUROC = 0.88 [0.81-0.94]). Conclusion: Low serum folic acid levels were identified as an independent risk factor for NAFLD in the Chinese population. The addition of the serum folic acid levels to the current existing NAFLD prediction scores significantly improved the prediction of NAFLD. (C) 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.