200–400 mg/day of silymarin.
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Milk thistle is a spiny plant native to the Mediterranean basin whose fruit contains a complex of flavonolignans known generically as silymarin, a mixture whose most studied component is silibinin and whose hepatoprotective profile has sustained its use in European clinical hepatology for decades, especially in Germany, where it is included in the official pharmaceutical formulary for specific liver indications.
Silymarin acts through several mechanisms relevant to liver health simultaneously: it stabilizes the hepatocyte membrane against toxins, raises intracellular levels of glutathione (the main endogenous antioxidant), stimulates regeneration of liver cells via ribosomal protein synthesis, and modulates inflammation through several mediators; this multimodal combination explains why its clinical profile is broader than that of a simple antioxidant.
The most spectacular and formally recognized indication of silibinin is as an antidote in Amanita phalloides poisoning, the mushroom whose accidental ingestion causes one of the most severe hepatotoxicities described in medicine; intravenous silibinin (Legalon SIL) given early significantly reduces mortality and the need for liver transplantation in amatoxin poisoning, an indication that remains in hepatology emergency protocols throughout Europe.
In chronic liver disease (viral hepatitis C before modern antivirals, nonalcoholic fatty liver disease, alcoholic hepatitis), several trials have shown modest improvements in transaminases (ALT, AST, GGT) and in markers of liver inflammation with doses of 280–600 milligrams daily of standardized silymarin for months; the effects on liver fibrosis measured by elastography are weaker but point in the same direction.
In alcoholic liver disease, silymarin remains one of the few pharmacological interventions with some (modest) evidence beyond abstinence, especially as an adjunct to reduce the hepatic oxidative stress associated with chronic alcohol consumption; in nonalcoholic fatty liver disease (NAFLD) the evidence is heterogeneous but points to benefits when combined with diet and exercise changes.
In type 2 diabetes, several trials have shown modest but significant improvements in fasting blood glucose, HbA1c, and lipid profile with 200–700 mg/day of silymarin for 4 months; the mechanism combines improved insulin sensitivity with antioxidant effects that reduce the pancreatic beta-cell damage associated with chronic diabetes.
In drug-induced hepatotoxicity (especially from chemotherapy drugs, antituberculosis drugs, and antiepileptics), silymarin is used as an adjunct to reduce the elevation of transaminases and allow the causative treatment to be maintained, an indication where the evidence is promising although heterogeneous across studies.
The doses studied range from 200 to 700 milligrams daily of standardized silymarin (it is important to choose products standardized to 70–80 percent), divided into two or three doses with or without food; products with enhanced bioavailability (silymarin-phosphatidylcholine, called Siliphos) have much higher absorption and allow effects to be achieved with lower doses.
Generally very well tolerated; the most frequent adverse effects are mild digestive discomfort; people who take drugs metabolized by the hepatic cytochrome P450 (anticoagulants, antiepileptics, cyclosporine) may experience mild to moderate interactions, which makes it prudent to consult a doctor before complex combinations; in pregnancy and breastfeeding the data are limited, although it has historically been used with no problems reported in the short term.
Information, not medical advice. Scientific evidence reflects the quality of the studies.