Silymarin, extract of milk thistle, does not benefit hepatitis C

Silymarin, an extract of milk thistle widely used around the world for treating liver disease caused by the hepatitis C virus, provides no more benefit than a placebo, researchers reported this week. Some estimates are that as many as a third of the estimated 3.2 million Americans with hepatitis C -- as well as many more millions around the world -- are consuming the drug in an effort to alleviate their symptoms. The new research by a team headed by Dr. Michael W. Fried of the University of North Carolina School of Medicine suggests that they are simply wasting their money.

“Patients ask me about milk thistle all the time,” Fried said. “Now I can tell them with great confidence that taking milk thistle, unfortunately, won’t help for chronic hepatitis C.”

Silymarin, derived from the plant Silybum marianum, is thought to have antioxidant, anti-inflammatory and antiviral properties, which would seem to make it a good tool for fighting hepatitis C. Fried and his colleagues recruited 154 people with chronic hepatitis C who had failed treatment with conventional interferon-based therapy. They were divided into three groups: One group received 420 milligrams of silymarin three times a day for 24 weeks, one received 720 milligrams three times a day and one a placebo. The researchers measured the patients’ enzyme levels at the beginning of the trial and at the end.

The team reported in the Journal of the American Medical Assn. that they found no significant differences between the groups. Two patients in each dosage group of silymarin showed an improvement in liver enzyme levels and two patients in the placebo group also did.

“This was the strongest, most methodologically sound clinical trial to date of silymarin as a treatment for chronic hepatitis C infection, and we found that it had absolutely no effect on [liver enzyme levels] or levels of the hepatitis C virus,” Fried said. “That was a surprise to us. We expected it to show at least some effect.”

The researchers used a high-quality silymarin product manufactured in Europe. They observed no adverse effects from the supplement but cautioned that consumers may not be aware of all the contents of other products.

The study was funded primarily by the National Institutes of Health and the National Center for Complementary and Alternative Medicine.

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