Across 8 studies, 5 reported beneficial effects of thistle (silymarin) on reducing aspartate aminotransferase (AST) levels, with effect sizes ranging from small to large (predominantly large). The evidence is strongest in clinical populations with liver conditions (NAFLD, ALD, hepatitis) and metabolic syndrome, with effects typically observed at 12 weeks or longer. Doses ranged from 420 mg/day (140 mg three times daily) to 800 mg/day, though many studies did not specify dosing.
Caveats: Effect sizes varied widely from small to large across studies; three studies found no significant effect. Most evidence comes from clinical populations — benefit in healthy individuals is less established. Dosing and form (silymarin) were not consistently reported, limiting dose-response conclusions. Many studies had short durations, and the median of 90 days was derived from only 3 of 8 studies.
The silymarin use increased the rate of patients with adverse effects [RR:1.11, 3.54]
from: Efficacy of different interventions for nonalcoholic fatty liver disease: A meta-analysisNo adverse effects were found in volunteers using silymarin (0.8 g/day), silymarin+yacon (0.8+2.4 g/day) and silymarin+maca (0.6+0.2 g/day).
from: Maca (Lepidium meyenii) and yacon (Smallanthus sonchifolius) in combination with silymarinNo adverse events were noted and both silymarin and placebo were well tolerated.
from: A randomized controlled trial to assess the safety and efficacy of silymarin on symptoms,gastrointestinal problems were the most common adverse effects.
from: Efficacy of different interventions for nonalcoholic fatty liver disease: A meta-analysisSilibinin capsules exhibited a favorable safety profile, with only mild gastrointestinal reactions and reports of insomnia as adverse events.
from: Evidence construction of Silibinin capsules against alcoholic liver disease based on a metSilibinin capsules exhibited a favorable safety profile, with only mild gastrointestinal reactions and reports of insomnia as adverse events.
from: Evidence construction of Silibinin capsules against alcoholic liver disease based on a metor medications [SMD: -1.41 (-2.24, -0.59), p=0.005].
[SMD =-0.14, 95% CI (-0.23, -0.06), P = 0.001(AST)]
AST [SMD = -1.56, 95% CI (-2.18, -0.95)]
other variables including direct bilirubin, ALT and aspartate aminotransferase (AST) were not significantly reduced
No adverse effects were found in volunteers using silymarin (0.8 g/day), silymarin+yacon (0.8+2.4 g/day) and silymarin+maca (0.6+0.2 g/day). A moderate AST level and diastolic blood pressure increase was found in volunteers using maca (0.6 g/day).
Mean improvements in ALT, AST, ALP, and GGT were significantly greater with the nutraceutical product than placebo (p ≤ 0.001).
silymarin had the highest effect on the reduction of AST (SMD = -2.68)
In contrast, quercetin and curcumin supplementation did not show a statistically significant difference compared to control groups in these outcomes.