Silybum marianum, commonly known as milk thistle, has a long history of use in traditional herbal medicine for supporting liver (hepatic) health. The primary active constituent, silymarin, is a complex of flavonolignans that has been extensively studied for its hepatoprotective properties. Scientific research, including randomized controlled trials and meta-analyses, provides moderate to strong evidence that silymarin can benefit liver function, particularly in cases of liver injury caused by toxins, alcohol, or certain medications. Proposed mechanisms of action include antioxidant activity, inhibition of lipid peroxidation, enhancement of protein synthesis, and stabilization of liver cell membranes.

Clinical studies have demonstrated improvements in liver function tests (such as ALT and AST levels) in patients with chronic liver diseases, including alcoholic liver disease, non-alcoholic fatty liver disease (NAFLD), and hepatitis C, although results are sometimes mixed. A 2017 Cochrane review concluded that while milk thistle appears safe and may slightly reduce liver-related mortality, the overall quality of evidence is low to moderate and more rigorous studies are needed.

Nevertheless, milk thistle remains one of the most widely researched and used herbal remedies for hepatic support, with a safety profile that is generally considered favorable. Its use is justified by both tradition and a substantial, though not yet definitive, body of scientific evidence.