The Effects of Silymarin on the Features of Cardiometabolic Syndrome in Adults: A Systematic Review and Meta-analysis

Some medicinal herbs and their effective components showed positive effects on the features of the cardiometabolic syndrome (CMS). The aim of the present systematic review and meta-analysis is to examine the effects of silymarin on the components of CMS in adults. Four electronic databases including PubMed/Medline, Scopus, Web of Science, and Embase were systematically searched up to December 31, 2020 to identify all eligible clinical trials. A random-effect model using DerSimonian and Laird method was used to estimate the pooled weighted mean differences (WMDs) and the 95% confidence intervals (95%CIs). Finally, 11 clinical trials met the eligibility criteria. Our results demonstrated that silymarin significantly reduced the levels of fasting blood glucose (WMD: -17.96 mg/dL, 95% CI: -32.91, -3.02;I : 82.4%, p < 0.001), hemoglobin A1C (WMD: -1.25%, 95% CI: -2.34, 0.16; I : 92.9%, p ˂ 0.001), total cholesterol (WMD: -17.46 mg/dL, 95% CI: -30.98, -3.95; I  = 62.9%, p = 0.006), triglyceride (WMD: -25.70 mg/dL, 95% CI: -47.23, -4.17; I :54.3%, p = 0.025), low-density lipoprotein-cholesterol (WMD: -10.53, 95% CI: -19.12, -1.94; I2: 37.5%, p = 0.119) and increased high-density lipoprotein- cholesterol (WMD: 3.36 mg/dL, 95% CI: 0.88, 5.84; I : 37.4%, p = 0.120) compared to placebo. However, its effects on BMI were not statistically significant. Silymarin can be an effective complementary therapy to improve most features of CMS. However, due to high heterogeneity and limited clinical trials in some parameters, further high-quality clinical trials are needed to confirm its efficacy.