Liver disease from alcoholA comprehensive review by the U.S. Agency for Healthcare Research and Quality (AHRQ) recently identified 16 scientific studies on the use of milk thistle for the treatment of various forms of liver disease. A European standardized extract of milk thistle was used in most of the trials.Problems in study design (such as small numbers of participants, variations in the causes of liver disease, and differences in dosing and duration of milk thistle therapy) made it difficult to draw any definitive conclusions. However, five of seven studies evaluating milk thistle for alcoholic liver disease found significant improvements in liver function. Those with the mildest form of the disease appeared to improve the most. Milk thistle was less effective for those with severe liver disease such as cirrhosis. Cirrhosis is characterized by scarring and permanent, non-reversible damage to the liver. It is often referred to as end-stage liver disease.Viral hepatitisDespite the fact that milk thistle is widely used in the treatment of hepatitis (particularly hepatitis C), results from four viral hepatitis studies were contradictory. Some found improvements in liver enzyme activity while others failed to detect these benefits. None of the studies compared milk thistle with interferon or other medications for viral hepatitis.CancerPreliminary laboratory studies also suggest that active substances in milk thistle may have anti-cancer effects. One active substance known as silymarin has strong antioxidant properties and has been shown to inhibit the growth of human prostate, breast, and cervical cancer cells in test tubes. Further studies are needed to determine whether milk thistle is safe or effective for people with these forms of cancer.High cholesterolOne animal study found that silymarin (an active compound in milk thistle) worked as effectively as the cholesterol-lowering drug probucol, with the additional benefit of substantially increasing HDL (good) chol