Effects of gut microbial therapy on lipid profile in individuals with non-alcoholic fatty liver disease: an umbrella meta-analysis study

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD), the most common liver disease, is closely associated with metabolic conditions such as obesity and diabetes mellitus, which significantly impact human health outcomes. The impaired lipid profiles observed in NAFLD individuals can further contribute to cardiovascular events. Despite the high prevalence of NAFLD, there is currently no confirmed intervention approved for its treatment. This study aimed to summarize the results of meta-analysis studies of randomized control trials assessing the impact of gut microbial therapy (probiotics, synbiotics, and prebiotics) on the lipid profile of individuals with NAFLD. METHODS: A systematic search was conducted on PubMed, Scopus, Web of Science, and Cochrane Library up to November 1, 2022. Meta-analyses surveying the impact of microbial therapy on lipid profile parameters (triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and total cholesterol (TC)) in the NAFLD population were included in our umbrella review. The final effect size (ES) was estimated, and sensitivity and subgroup analyses were performed to explore heterogeneity. RESULTS: Fifteen studies were included in this umbrella review. Microbial therapy significantly reduced TG (ES − 0.31, 95% CI − 0.51, − 0.11, P < 0.01), TC (ES − 1.04, 95% CI − 1.46, − 0.61, P < 0.01), and LDL (ES − 0.77, 95% CI − 1.15, − 0.39, P < 0.01) in individuals with NAFLD. However, the effect on HDL was not statistically significant (ES − 0.06; 95% CI − 0.19, 0.07, P = 0.39). CONCLUSION: Considering the absence of approved treatments for NAFLD and the promising role of microbial therapies in improving the three lipid profiles components in individuals with NAFLD, the use of these agents as alternative treatment options could be recommended. The findings underscore the potential of gut microbial therapy, including probiotics, synbiotics, and prebiotics, in managing NAFLD and its associated metabolic complications. TRIAL REGISTRATION: PROSPERO (CRD42022346998). GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13643-023-02299-x.