An herbal remedy called milk thistle that’s a favorite among people with liver problems is under the gun from a new study that questions its effectiveness—but may be less conclusive than recent headlines suggest. The fuss has put alternative-treatment advocates on the defensive about a seed extract that they say has truly made a difference for people fighting the liver side effects of certain HIV medications or suffering from hepatitis or coinfection (both HIV and hepatitis C), not to mention alcoholism.

According to a report in the November issue of the American Journal of Gastroenterology, the so-called meta-analysis, a Cochrane Collaboration review of 13 previous studies, found no proof yet that milk thistle was actually rebuilding anyone’s liver. “MT does not seem to significantly influence the course of patients with alcoholic and/or hepatitis B or C liver diseases,” the study reads.

But milk thistle defenders, like George Carter at the Foundation for Integrative AIDS Research, accuse the Cochrane researchers of putting a “negative spin” on the earlier data. He points out that the study says, “Milk thistle could potentially affect liver injury” and that it concludes that under the right circumstances, the seed’s benefits might just be provable: “Adequately conducted randomized clinical trials on MT versus placebo may be needed,” the study recommends.

Even lead researcher Christian Gluud, MD, of Copenhagen University Hospital, told Medical News Today, “We are still not in a situation where we can exclude a potential beneficial or harmful effect.”

Carter, who has hep C himself, is not one to argue that milk thistle on its own can keep a diseased liver functioning and healthy. “Most people are using it with whey proteins, alpha-lipoic acid and other natural supplements,” he says. “The bottom line is that we need more data.”

Antonio Urbina, MD, an AIDS doc at St. Vincent’s Hospital in New York City, says he’s not surprised by the milk thistle debate, given all the attention paid lately to herbal supplements and Eastern remedies—attention that he welcomes. “Make sure there are no drug interactions between any herbal medication and your antiretrovirals,” Urbina strongly recommends.

But he says the findings of this new study are not compelling enough to counter his own anecdotal information–i.e. the HIV positive and coinfected patients in his own practice who take milk thistle without problems—and so he won’t rule out the seed extract yet. However, he says, “At this point, I would advise against taking milk thistle until more studies were done.”