The Scoop on Milk Thistle for Hepatitis C

Over the years, many of my hepatitis C patients have asked if milk thistle would provide additional benefit during treatment of their hepatitis C virus (HCV) infection. Since this herb doesn’t have any side effects (aside from a mild laxative effect in a small number of people), I’ve been open to my patients using it if they wanted. However, I’ve been waiting for more definite human clinical research with this herb before going so far as recommending it to my patients. And now, it seems, some interesting evidence has finally been published – although it unfortunately does not come out in support of this herb.  

The milk thistle research of Michael Fried, M.D., from the University of North Carolina at Chapel Hill, and colleagues was published recently in the Journal of the American Medical Association. Dr. Fried concluded that milk thistle wasn’t significantly different from a placebo for the liver health of chronic hepatitis C patients. 

The 154 patients in Dr. Fried’s double-blind study are considered “hard to treat” since they had already failed interferon-based therapy. Of these patients, 88 were given silymarin extracted from milk thistle (either 420 mg. or 700 mg., three times per day) and the other 50 got a placebo. All of the patients had chronic HCV infection, and serum alanine aminotransferase (ALT) levels of 65 U/L or greater. Treatment with milk thistle (or placebo) lasted 24 weeks.  


Dr. Fried’s team was tracking two main outcomes: 

1. Decrease in ALT to within normal range (e.g., 45 or less). ALT is a liver enzyme that is indicative of liver damage. 
2. Any change to ALT level, HCV RNA levels, and quality-of-life 

Neither of these outcomes was significantly different between the placebo and milk thistle groups. Two patients in the milk thistle group saw a decline to normal ALT, but two placebo patients also reached this milestone.  

Dr. Fried’s work will certainly take some of the wind out of milk thistle’s sails, but it probably won’t be the last we’ll hear from this herb. This is because other researchers continue to find promise with milk thistle when it comes to the liver.  

Last year researchers published results of a preliminary study about liver function in people infected with hepatitis C. Similar to Dr. Fried’s work, this study provided milk thistle supplements (630 mg. of silymarin per day) to 55 patients for 24 weeks. There was a statistical difference in ALT levels in this study: from an average of 108.7 before treatment down to an average of 70.3 after treatment. In addition, this study found improved serum HCV-RNA titer, hepatic fibrosis, and patient’s quality-of-life after milk thistle supplementation.  

However, this study’s conclusions are not as robust as Dr. Fried’s work since there was no control group and therefore it can’t be relied on for evidence as much as Dr. Fried’s study. For now, milk thistle remains unproven as an adjunct HCV treatment, although I’ll certainly be keeping an eye out for any additional research with this herb.   

Stephen C Vogt, PharmD
President and CEO
BioPlus SP

Fried MW, Navarro VJ, Afdhal N, et al. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy. JAMA 2012; 308(3): 274-282.
Kalantari H, Shahshahan Z, Hejazi SM, et al. Effects of Silybum marianum on patients with chronic hepatitis C. J Res Med Sci 2011;16(3):287-90.

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