Flavonolignans, particularly those found in Silybum marianum (milk thistle), such as silybin, silychristin, and silydianin, are widely used in herbal medicine to support liver health and detoxification. The primary scientific support comes from studies on silymarin, a standardized extract of milk thistle seeds that is rich in flavonolignans. Research has demonstrated that silymarin possesses antioxidant, anti-inflammatory, and membrane-stabilizing properties, which may help protect hepatocytes (liver cells) from toxic injury and promote their regeneration.

Clinical evidence for milk thistle and its flavonolignans includes randomized controlled trials and meta-analyses, mainly involving patients with liver diseases such as alcoholic liver disease, nonalcoholic fatty liver disease, and hepatitis. Some studies report improvements in liver enzymes (ALT, AST) and symptoms, but results are inconsistent and often limited by methodological issues such as small sample sizes and short durations. There is modest evidence that flavonolignans can reduce markers of oxidative stress in the liver and may reduce the severity of toxin-induced liver damage (e.g., from Amanita phalloides poisoning), but conclusive large-scale data are lacking.

Overall, the use of flavonolignans for liver detoxification is supported by a moderate level of scientific evidence, especially for general hepatoprotection, though not all purported benefits are rigorously validated. Their traditional use for liver health is also robust, but the evidence rating here is based on available scientific studies.