The effect of synbiotics in patients with NAFLD: a systematic review and meta-analysis

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the highest incidence of chronic liver disease worldwide, seriously endangering human health, and its pathogenesis is still unclear. In the recent years, increasing evidence has shown that intestinal flora plays an important role in the occurrence and development of NAFLD. Synbiotics can alter gut microbiota and may be a treatment option for NAFLD in the future. OBJECTIVES: To systematically investigate the therapeutic effect of synbiotic supplementation on NAFLD patients. DESIGN: A systematic review and meta-analysis were conducted. DATA SOURCES AND METHODS: We conducted a search on four databases (PubMed, Embase, Cochrane Library, and Web of Science) to identify relevant studies. Eligible studies were then screened, and data from the included studies were extracted, combined, and analyzed. RESULT: This study analyzed 10 randomized controlled trials involving 634 patients with NAFLD. The results showed that synbiotic supplementation could significantly reduce the level of alanine aminotransferase (mean difference (MD) = −8.80; (95% CI [−13.06, −4.53]), p < 0.0001), aspartate aminotransferase (MD = −9.48; 95% CI [−12.54, −6.43], p < 0.0001), and γ-glutamyl transferase (MD = −12.55; 95% CI [−19.40, −5.69], p = 0.0003) in NAFLD patients. In the field of metabolism, synbiotic supplementation could significantly reduce the level of total cholesterol (MD = −11.93; 95% CI [−20.43, −3.42], p = 0.006) and low-density lipoprotein cholesterol (MD = −16.2; 95% CI [−19.79, −12.60], p < 0.0001) and increase the level of high-density lipoprotein cholesterol (MD = 1.56; 95% CI [0.43, 2.68], p = 0.007) in NAFLD patients. In addition, synbiotic supplementation could significantly reduce liver stiffness measurement indicator (MD = −1.09; 95% CI [−1.87, −0.30], p = 0.006) and controlled attenuation parameter indicator (MD = −37.04; 95% CI [−56.78, −17.30], p = 0.0002) in NAFLD patients. CONCLUSION: Based on the current evidence, synbiotic supplementation can improve liver function, adjust lipid metabolism, and reduce the degree of liver fibrosis in patients with NAFLD, but these effects need to be confirmed by further studies.