Chapter 1 of 13
Milk Thistle
The Essentials

Silymarin — a complex of flavonolignans (silybin A/B, silychristin, silydianin, isosilybin) — is the active fraction. The whole crushed seed contains 1.5–3% silymarin.
The best clinical evidence supports non-alcoholic fatty liver disease (NAFLD) — meta-analyses (a study that pools the results of many trials) show modest reductions in ALT and AST across multiple RCTs.
The seed tea is weak — bioavailability (how much of it your body can actually absorb) of silymarin from a hot-water infusion (a drink made by steeping the plant in hot water) is low. Standardised extracts (70–80% silymarin) are the therapeutic form.