Milk thistle is a flavenoid that, in vitro, has antioxidant and anti-inflammatory effects. Patients with liver disease use this supplement as an alternative to, or addition to conventional hepatitis C therapy. According to data presented at the American Association for the Study of Liver Diseases annual meeting, it is of no benefit for the treatment of hepatitis C.

The findings comes from a randomised multicentre trial which recruited 154 hepatitis C patients who had not responded to interferon therapies and had serum alanine aminotransferase (ALT) enzyme levels > 65 IU/L, with a median of 106 IU/L (normal level = 45 IU/L). They were randomised to one of three groups, two of which involved high doses of a standardised form (420mg or 700mg TDS) and the third, placebo. The doses of milk thistle, which were selected based on results of an earlier phase I study, were 4.5 to 7.5 times higher than customary. Of the 138 patients who completed the 24-week study, 90% were able to adhere to at least 80% of the pill regimen. The mean drop in serum ALT was not significantly different between the three groups, and only two patients in each group met the primary endpoint, either normalisation of ALT or a drop of at least 50% from baseline.