A commentary published earlier this year in the Journal of the American Medical Association (JAMA) argued that the National Center for Complementary and Alternative Medicine (NCCAM) should stop funding studies of alternative medical treatments that don’t have a sound biological basis. Why? Because when the studies’ findings come up negative (as they inevitably seem to do), they have no effect on behavior.

In other words, people keep on using the ineffective supplement or treatment anyway.

The tax monies that support NCCAM ($130 million in 2012) would be better spent elsewhere, said the commentary’s author, Dr. Paul Offit, a pediatrician and infectious disease expert at the University of Pennsylvania.

I thought of that commentary as I read through a new NCCAM-funded study, published this week in JAMA. It found that the popular herbal dietary supplement silymarin, an extract from milk thistle, works no better than placebo at helping people with chronic hepatitis C infections.

Past research on silymarin has suffered from poor methodology and has delivered inconsistent findings. Yet that lack of evidence hasn’t stopped a third of patients with chronic hepatitis C infections and cirrhosis of the liver from using silymarin for the treatment of their disease (usually as an adjunct to standard drug treatment). In 2008 (the latest sales figures I could find), Americans spent $95 million on milk thistle supplements, according to several accounts of a report from the Nutrition Business Journal.

Those sales have been helped by the promotion of the supplement by none other than Oprah Winfrey’s TV protégé, Dr. Mehmet Oz, who shamelessly recommends milk thistle as a “quick fix” for alcohol overindulgence because it will “boost your livers [sic] enzyme function.”

The study’s details

Will this new study on milk thistle change anybody’s minds? It’s certainly well designed. For the study, 154 participants — all of whom had chronic hepatitis C and had already failed conventional interferon-based therapy for the illness — were randomized to two basic treatment groups. One group took silymarin (either 420 milligrams or 700 milligrams) three times a day for 24 weeks. These doses were three to five times higher than is customary, explain the study’s authors, because testing had suggested such doses might be more effective. The other treatment group was given a placebo. The study was double-blinded, which meant neither the volunteers nor the researchers knew who was taking which pill.

At the study’s end, there was no difference between the treatment groups in the main outcome that was measured: blood levels of alanine aminotransferase (ALT) enzymes. The researchers were looking for a normalization of ALT levels (a measurement of 40 units per liter or less) or a drop in the levels of at least 50 percent since the start of the study. They found that only four patients — two in the silymarin arm of the study and two in the placebo arm — met either of these outcomes.

The study also found no differences between the treatment groups in qualify-of-life measures.

We’ll have to wait and see if this evidence has any effect on the sales of milk-thistle supplements  — and if Dr. Oz retracts his recommendation. But I’m not holding my breath.