Milk thistle (Silybum marianum) is an herb thatβs touted for its antioxidant capabilities and is commonly used to support the liver. Studies have shown milk thistleβs ability to reduce liver inflammation and damage, particularly to reduce damage caused by free radicals. Milk thistleβs active medicinal ingredient, an antioxidant known as silymarin, is responsible for its protective and regenerative effects on the liver.