Milk Thistle extract is standardized to 80% silymarin. Silymarin is the key constituent that exerts a protective effect against substances potentially harmful to the liver. Nature's Way Standardized Milk Thistle extract is a technically advanced herbal product. Standardization assures specific measurable levels of important compounds that provide beneficial activity in the body. Contains no artificial coloring, artificial flavoring, corn, dairy products, gluten, preservatives, salt, soy, sugar, wheat, and yeast.