Milk thistle is a plant named for the white veins on its large prickly leaves.
One of the active ingredients in milk thistle is silymarin, which is extracted from the plant's seeds. Silymarin is a flavonoid believed to have antioxidant properties.
Milk thistle is sold as an oral capsule, tablet, powder and liquid extract. People mainly use the supplement to treat liver conditions.
Evidence
Research on milk thistle use for specific conditions shows:
Diabetes. Milk thistle might lower blood sugar in people who have type 2 diabetes.
Indigestion (dyspepsia). Milk thistle, in combination with other supplements, might improve the symptoms of indigestion.
Liver disease. Research on the effects of milk thistle on liver disease, such as cirrhosis and hepatitis C, has shown mixed results.