Research synthesisModerate evidenceMixed effect size6 studies · 4 beneficial · 2 neutral · 0 harmful
Across 6 studies, 4 reported beneficial effects of thistle (silymarin/silibinin) on reducing alanine aminotransferase (ALT) levels, with effect sizes ranging from small to large, and 2 found neutral results. The two highest-quality meta-analyses (evidence scores of 7) both showed statistically significant beneficial effects — one in NAFLD patients (moderate effect, SMD -0.47 to -0.88) and one in patients on anti-TB drugs (small effect, SMD -0.15). The median study duration across the 2 studies that reported it was 104 days (approximately 15 weeks), indicating effects are typically observed after several weeks of supplementation.
- Effective dose range: 140 mg three times daily (reported in one RCT; other studies did not specify dose)
- Studied populations: Clinical populations with nonalcoholic fatty liver disease (NAFLD), alcoholic liver disease, and patients on antituberculosis drugs at risk for drug-induced liver injury
Caveats: Available evidence is overwhelmingly positive (4 of 6 studies beneficial) — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). The evidence base includes only 6 studies, and 2 of them were neutral (non-significant), including one RCT in acute hepatitis. Effect sizes varied substantially across studies (small to large), and most studies did not report specific doses or forms of thistle, limiting precise dosing guidance.
Generated Jun 15, 2026