Human / Clinical Studies
A randomized, controlled trial supported by the National Institute of Diabetes and Digestive and Kidney Diseases examined patients with chronic hepatitis C who had failed prior antiviral therapy. All patients had advanced chronic liver disease consisting of histologic evidence of either marked fibrosis or cirrhosis. The Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis trial used a half dose of pegylated interferon versus no treatment; the treatment was to be administered for 3.5 years. The aim was to reduce progression of chronic hepatitis C, particularly in the development of hepatocellular carcinoma. Among 1,145 study participants, 56% had never taken herbals, 21% admitted past use, and 23% were using herbals at enrollment. Silymarin constituted 72% of the 60 herbals used at enrollment. Users had significantly fewer symptoms and a better quality of life than nonusers.
Although there are many reports of the use of herbals for the treatment of chronic liver diseases, most treatment trials have suffered from poor scientific design, uncertainty of the required dosage of herbals, and an insufficient number of study participants. A recent review of complementary and alternative medications (CAM) to treat liver diseases focused on the classification, epidemiology, and the philosophy of CAM and reviewed the criteria needed to conduct a scientifically valid research study focusing on herbal products.
There has been skepticism regarding the evidence that silymarin has a direct impact on the hepatitis C virus (HCV)—some studies suggest that it does, but most studies are unable to confirm these reports. However, at least two articles in major journals have suggested that silymarin or its congeners may inhibit HCV. In one report, investigators found that a standardized silymarin extract inhibited tumor necrosis factor -alpha in anti-CD3–stimulated human peripheral blood mononuclear cells and nuclear factor-kappa B-dependent transcription in human hepatoma Huh-7 cells. Silymarin also displayed prophylactic and therapeutic effects against HCV infection and when combined with interferon-alpha, was more inhibitory of HCV replication than was interferon alone. This indicates that silymarin has anti-inflammatory and antiviral effects in patients with chronic hepatitis C.