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Effects of Milk Thistle Extract on Chronic Hepatitis C

Milk Thistle

© Steven Foster

In a recent study, higher-than-usual doses of silymarin—an extract from the milk thistle plant—did not provide greater benefit than placebo for the treatment of hepatitis in patients with chronic hepatitis C who previously failed to respond to standard antiviral treatment. The study, funded by NCCAM and by the National Institute of Diabetes and Digestive and Kidney Diseases, was published in the Journal of the American Medical Association.

Chronic hepatitis C is a common liver disease, and may result in cirrhosis, liver failure, and liver cancer. Because many patients with hepatitis C do not respond to standard antiviral treatment, or are unable to undergo full treatment, other treatment options have been explored. Silymarin is the most commonly used botanical for liver disorders, including hepatitis C, in the United States. Previous laboratory research has suggested that milk thistle may provide benefit by protecting and promoting the growth of liver cells, fighting oxidation (a chemical process that can damage cells), and inhibiting inflammation. Results from previous small clinical trials (studies in humans) of milk thistle for various liver diseases have been mixed, however, and this recent trial focused on higher-than-usual doses of a single silymarin product in patients with chronic hepatitis C.

This double-blind, placebo-controlled, randomized trial was conducted in 154 participants with chronic hepatitis C at 4 different U.S. centers. All participants had been unsuccessfully treated with conventional antiviral medication. Researchers randomly assigned participants to receive 420 mg of silymarin, 700 mg of silymarin, or placebo administered three times per day for 24 weeks, to determine whether a 24-week course of silymarin had a significant impact on serum ALT, a marker of liver disease. Researchers also followed hepatitis C virus levels and assessed quality of life measures during the trial. (Twenty-four weeks is a commonly accepted duration of treatment for which effective hepatitis C therapies have previously demonstrated improvement in disease activity.) After assessing participants at the beginning of the study, researchers assessed participants at six followup visits, scheduled 2 to 8 weeks apart during the treatment period, and at 4 and 12 weeks after treatment.

The researchers observed no statistically significant differences among the three groups regarding changes in serum ALT levels from the beginning to the end of treatment. In addition, there were no significant changes in hepatitis C virus levels or in quality of life measures. The frequency of adverse events experienced by participants also did not differ significantly among the groups, although, this study was not designed to detect statistically significant differences among the groups with regard to adverse events. Trial results indicate that treatment with either higher-than-usual silymarin doses or placebo  in patients with treatment resistant hepatitis C does not change indicators of hepatitis C disease activity.


Publication Date: 
July 18, 2012

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This page last modified October 21, 2015