Effect of synbiotics on the cardiovascular risk factors in patients with non-alcoholic fatty liver: a GRADE assessed systematic review and meta-analysis

Introduction: Several studies revealed that synbiotics have been beneficial in managing non-alcoholic fatty liver disease (NAFLD), but the findings are conflicting. We aimed to assess the effect of synbiotic supplementation on cardiovascular risk factors in patients with NAFLD. Methods: A thorough literature search was conducted to identify relevant studies up to July 2024, including publications from Pubmed, Embase, Cochrane, Scopus, and the Web of Science. Standardized mean difference (SMD) was used, and data with a 95% confidence interval (CI) were presented. Results: Sixteen RCTs were included, involving NAFLD patients and synbiotic supplementation. No significant effects were found on blood pressure (SBP: SMD − 6.68, p = 0.234; DBP: SMD − 4.31, p = 0.391), anthropometric measures (weight: SMD − 0.78, p = 0.126; BMI: SMD − 0.21, p = 0.182; waist circumference: SMD − 0.53, p = 0.095), or lipid profile (triglycerides: SMD − 3.67, p = 0.266; total cholesterol: SMD − 0.61, p = 0.059; low-density lipoprotein: SMD − 3.09, p = 0.215; high-density lipoprotein: SMD 0.49, p = 0.219). Synbiotics significantly reduced CRP levels (SMD − 1.83, p = 0.019) but had no significant effect on TNF-α (SMD − 1.95, p = 0.087). Synbiotic led to a significant reduction in weight following adjustment of publication bias (SMD − 1.16, p < 0.05). Conclusion: Overall, synbiotic supplementation does not significantly impact blood pressure, anthropometric indices, or lipid profile parameters in patients with NAFLD, except for a significant reduction in weight after adjusting for publication bias. Synbiotic supplementation significantly reduces CRP levels but has no effect on TNF-α. © The Author(s) 2025.