Impact of Silymarin in individuals with nonalcoholic fatty liver disease: A systematic review and meta-analysis

Objectives Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease affecting a significant proportion of the general population. Recently, randomized clinical trials have been conducted examining the efficacy of silymarin in individuals with NAFLD, with conflicting results. The aim of this meta-analysis was to evaluate the efficacy of silymarin in the treatment of NAFLD by examining changes in liver biochemistry, body mass index, and liver histology. Methods We searched major electronic databases PubMed/MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials, as well as gray-literature sources, up to June 2020 for randomized clinical trials examining the efficacy of treatment with silymarin in individuals with NAFLD compared to placebo. The primary outcomes were changes in the mean values of transaminases (alanine aminotransferase and aspartate aminotransferase). Secondary outcomes included changes in body mass index and liver histology. Quality analysis was performed with the risk-of-bias tool 2.0. We synthesized results using weighted mean differences for continuous outcomes, along with 95% confidence intervals. Results In the meta-analysis, eight randomized clinical trials were included. A cutoff level of 0.05 was considered to provide statistically significant results. Silymarin treatment led to a statistically significant greater reduction in the levels of transaminases compared to placebo, irrespective of weight loss. Conclusions Silymarin seems to be effective in reducing transaminase levels in individuals with NAFLD. Despite the statistical benefits, we call attention to potential flaws related to the quality of the included studies. Further well-designed studies should be carried out to examine whether this reduction in transaminase levels corresponds to histologic improvement.