Supplement analysis backed by scientific evidence · PT

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Limited evidenceGeneral health

Milk Thistle (Silymarin)

Despite decades of use as a "liver protector," milk thistle has repeatedly failed its best-designed trials: a Cochrane review found no mortality or histology benefit in alcoholic and viral liver disease, and two well-run NASH trials missed their primary endpoints. The intravenous silibinin used for death-cap mushroom poisoning is a different, hospital-only product.

What the science says

  • Improves outcomes in alcoholic or viral liver disease Limited evidence

    A Cochrane systematic review of 13 randomized trials (915 patients) found milk thistle did not significantly reduce all-cause mortality, liver-related mortality, complications or histology in alcoholic and/or hepatitis B or C liver disease; apparent benefits were confined to trials at high risk of bias. This is the strongest evidence available and it is negative.

  • Treats non-alcoholic steatohepatitis (NASH) Limited evidence

    A 48-week randomized trial of silymarin 700 mg three times daily in biopsy-proven NASH failed its primary endpoint (a ≥30% reduction in NAFLD activity score) but showed improvement in fibrosis stage in a secondary analysis. A separate NIH-funded phase 2 trial (420 or 700 mg three times daily for 48-50 weeks) also did not meet its histologic primary endpoint. Network meta-analyses of natural products in NAFLD rank silymarin among the better-studied options, but with low certainty.

  • Lowers liver enzymes (ALT/AST) Moderate evidence

    Across NASH and drug-induced liver injury trials, silymarin fairly consistently produces modest reductions in ALT and AST. Whether an enzyme change without histologic or clinical improvement matters to patients is unresolved — the NASH trials showed you can get one without the other.

  • Antidote for Amanita (death cap) mushroom poisoning Moderate evidence

    Intravenous silibinin dihemisuccinate is used in Europe and under US expanded-access protocols for amatoxin poisoning, supported by large observational series rather than randomized trials. Oral milk thistle supplements have far lower bioavailability and are not a substitute.

Dosage & safety

Studied doseTrials used 280-2,100 mg/day of silymarin, most commonly 140 mg three times daily of an 80% standardized extract; the NASH trials went as high as 700 mg three times daily for 48 weeks. Silymarin is poorly absorbed; silybin-phosphatidylcholine complexes improve bioavailability several-fold at lower milligram doses.
SafetyGenerally well tolerated; the main effects are a mild laxative action, nausea and bloating. Allergic reactions occur in people sensitive to the Asteraceae family (ragweed, chrysanthemum, marigold, daisy). Silymarin inhibits CYP2C9 and UGT enzymes in vitro and may raise levels of warfarin, some statins and diabetes drugs — clinically significant interactions are uncommon but reported. It may lower blood glucose, adding to antidiabetic drugs. Data in pregnancy are inadequate. Using milk thistle as "liver cover" for alcohol or hepatotoxic drug use has no evidence base and may delay proper care.

Scientific references

Where to buy

California Gold Nutrition, Silymarin Complex, 120 Veggie Capsules

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