Elevated serum phosphatidylcholine (16:1/22:6) levels promoted by fish oil and vitamin D3 are highly correlated with biomarkers of non-alcoholic fatty liver disease in Chinese subjects.

The aim of the present study was to investigate the relationship between the changes of serum lipid metabolites and the risk factors of non-alcoholic fatty liver disease (NAFLD) after fish oil (FO) or fish oil plus vitamin D (FO + D) intervention in Chinese NAFLD subjects. Seventy-four NAFLD subjects, aged 55.2 ± 15.9 years, were randomized to consume FO + D (n = 23), FO (n = 27) or corn oil (CO, n = 24) capsules for a 3-month intervention. Serum lipid-related metabolites were measured with ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS)-based metabolomics approach together with multivariate data analysis. The differential metabolites were screened and identified with variable importance in projection (VIP) scores based on orthogonal partial least squares discriminant analysis models. Serum phosphatidylcholine (PC) (16:1/22:6) levels had the highest and second highest VIP scores following FO + D and FO interventions, respectively. Serum PC (16:1/22:6) levels were negatively correlated with circulating alanine transaminase (ALT) (r = -0.268, p = 0.021), triacylglycerol (TAG) (r = -0.236, p = 0.042), interleukin (IL)-1β (r = -0.401, p < 0.001) and tumor necrosis factor (TNF)-α (r = -0.322, p = 0.005) concentrations, and were positively correlated with high-density lipoprotein cholesterol (HDL-C) (r = 0.272, p = 0.019) concentrations. The present study was the first to report that serum PC (16:1/22:6) levels were highly correlated with ALT, TAG, HDL-C, IL-1β and TNF-α concentrations, indicating that PC (16:1/22:6) might ameliorate lipid metabolism and inflammation in NAFLD subjects.