Association of serum methionine metabolites with non-alcoholic fatty liver disease: a cross-sectional study

Background and project Non-alcoholic fatty liver disease (NAFLD) is viewed as the hepatic manifestation of metabolic syndrome. Methionine metabolites have been linked to metabolic syndrome and its related diseases. Whether serum methionine metabolites levels are associated with NAFLD remains unclear. The study aimed to assess the association between methionine metabolites and NAFLD. Methods This cross-sectional study included a total of 2814 individuals aged 40–75 years old. All participants underwent anthropometric measurements, laboratory tests, dietary assessment and abdominal ultrasonography. Multivariable logistic regression analysis was performed to estimate the association of methionine metabolites with NAFLD. Results Overall, 1446 with and 1368 without NAFLD were enrolled in this study. Participants with NAFLD had significantly higher serum S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and homocysteine (Hcy) levels, and a lower S-adenosylmethionine/S-adenosylhomocysteine (SAM/SAH) ratio than those without NAFLD (all P < 0.001). After adjusting multiple confounders, odds ratios (95% confidence interval) for quartile 4 versus quartile 1 of SAH, Hcy and SAM/SAH ratio were 1.65 (1.27–2.14), 1.63 (1.26–2.12) and 0.63 (0.49–0.83), respectively (all P for trend < 0.01). In addition, serum SAH, Hcy levels and SAM/SAH ratio were significantly correlated with the degree of hepatic steatosis (all P for trend < 0.001). Conclusion Elevated serum SAH, Hcy levels and lower SAM/SAH ratio may be independently associated with the presence of NAFLD in middle-aged and elder Chinese.