Administration of Silymarin in NAFLD/NASH: A systematic review and meta-analysis

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease with a high prevalence worldwide and poses serious harm to human health. There is growing evidence suggesting that the administration of specific supplements or nutrients may slow NAFLD progression. Silymarin is a hepatoprotective extract of milk thistle, but its efficacy in NAFLD remains unclear. Relevant studies were searched in PubMed, Embase, the Cochrane Library, Web of Science, clinicaltrails.gov, and China National Knowledge Infrastructure and were screened according to the eligibility criteria. Data were analyzed using Revman 5.3. Continuous values and dichotomous values were pooled using the standard mean difference (SMD) and odds ratio (OR). Heterogeneity was evaluated using the Cochran's Q test (I2 statistic). A P<0.05 was considered statistically significant. A total of 26 randomized controlled trials involving 2,375 patients were included in this study. Administration of silymarin significantly reduced the levels of TC (SMD[95%CI]=-0.85[-1.23, -0.47]), TG (SMD[95%CI]=-0.62[-1.14, -0.10]), LDL-C (SMD[95%CI]=-0.81[-1.31, -0.31]), FI (SMD[95%CI]=-0.59[-0.91, -0.28]) and HOMA-IR (SMD[95%CI]=-0.37[-0.77, 0.04]), and increased the level of HDL-C (SMD[95%CI]=0.46[0.03, 0.89]). In addition, silymarin attenuated liver injury as indicated by the decreased levels of ALT (SMD[95%CI]=-12.39[-19.69, -5.08]) and AST (SMD[95% CI]=-10.97[-15.51, -6.43]). The levels of fatty liver index (SMD[95%CI]=-6.64[-10.59, -2.69]) and fatty liver score (SMD[95%CI]=-0.51[-0.69, -0.33]) were also decreased. Liver histology of the intervention group revealed significantly improved hepatic steatosis (OR[95%CI]=3.25[1.80, 5.87]). Silymarin can regulate energy metabolism, attenuate liver damage, and improve liver histology in NAFLD patients. However, the effects of silymarin will need to be confirmed by further research.