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Milk thistle (silymarin)

EMA-monograph hepatoprotective with the most consistent evidence in non-alcoholic and drug-induced liver complaints.

Why

Milk thistle (Silybum marianum) extract, standardised to silymarin (a complex of flavonolignans including silybin), holds an EMA Well-Established Use monograph for supportive treatment in chronic inflammatory liver disorders. The Cochrane review of milk thistle for alcoholic and viral hepatitis was inconclusive overall, but more recent RCTs and meta-analyses in non-alcoholic fatty liver disease report consistent improvements in ALT, AST and steatosis.

How it works

Silybin scavenges free radicals, stabilises hepatocyte membranes, inhibits hepatic stellate-cell activation (the fibrogenic cell type), and competes with toxin uptake at the hepatocyte basolateral membrane, the basis of the antidote indication in Amanita phalloides poisoning.

Expected onset · Transaminase changes typically over 8–12 weeks of consistent intake

How to take

Dosage

Silymarin 420–600 mg/day in divided doses, with food. Higher doses (1,400 mg/day) used in NAFLD trials.

Timing

With meals; divided 2–3 times daily

On the label

Look for an extract standardised to silymarin (typically 80%) or silybin specifically. Phospholipid-complex forms (e.g. Siliphos) and Legalon SIL have better bioavailability than raw extract.

Ideal for

Adults with non-alcoholic fatty liver disease, drug-induced transaminitis, or chronic mild liver enzyme elevation under clinical supervision.

Safety

Generally well tolerated; occasional GI upset. Mild CYP2C9 inhibition. Caution with warfarin and phenytoin at higher doses. Allergic reactions in those sensitive to Asteraceae. Pregnancy data limited but no safety signals in observational data.

Evidence

At a glance

EMA HMPC classifies the fruit extract as Well-Established Use for chronic inflammatory liver disorders. Zhong 2017 Medicine meta-analysis (8 RCTs, n=587 NAFLD): silymarin significantly reduced ALT and AST vs placebo. Cochrane 2007 SR on alcoholic/viral hepatitis was inconclusive, the more consistent signal is in metabolic-associated steatohepatitis and as an adjunct in drug-induced transaminitis.

Where to get it

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