This week, Columbia University finally cut ties with Dr. Mehmet Oz, a former surgeon turned TV personality who became famous through his TV show, which he often used to promote all kinds of pseudoscience. Columbia’s medical school had long complained about Oz, writing in a public letter years ago that:
“[Dr. Oz] has manifested a blatant lack of integrity in promoting healers and cures for personal financial gain.”
That letter didn’t convince Columbia to kick Dr. Oz out of college, but declaring his candidacy for the Pennsylvania Senate seat appears to have worked. (Columbia did not respond to requests for comment from The Guardian.)
So, in honor of the new search for Dr. Oz, I’m republishing a column I wrote about him in 2013, when Oz performed what he called an “unprecedented experiment” live, on air. Not surprisingly, it was embarrassingly bad science. Maybe Pennsylvania voters should ask him about it.
Dr. Mehmet Oz hosts a popular TV show where he promotes all kinds of medical treatments, some good and some, well, not so good. And every once in a while, he tries to do a science experiment, like he did in 2011 with a very flawed experiment on arsenic in apple juice.
Well, Dr. Oz has done it again. This time he wanted to re-examine a claim he himself had made on a previous show about green coffee bean extract.
In April 2012, Oz aired a segment on his television show called “Green Coffee Bean Extract: The Fat Burner That Works!” In it, “This miracle pill can burn fat fast, for anyone who wants to lose weight.” Unsurprisingly, sales of green coffee bean extract soared in response.
“A marketing apocalypse is unleashed!” Dr. Oz noted on his show in September 2012. “I was surprised by the firestorm,” he said.
Dr. Oz loves this topic, by the way. He has done dozens of shows on weight loss gimmicks, including “The New Silver Bullet for Weight Loss,” in which he promoted a new diet pill called Qnexa, and “Ancient Ayurvedic Weight Loss Secrets.” But let’s leave that for another day.
One problem with Oz’s first green coffee bean program was that it was based on a study that has some serious problems. That study claimed that a particular brand of green coffee bean extract called GCA led to significant weight loss. The subjects also lost a lot of weight: 8 kilograms (over 17 pounds) on average. Dr. Oz called it “an amazing study just published.” Wow, that must be good, right?
Let’s see that study, okay? First, it only involved 16 people, a small sample. There were 3 treatments: high-dose GCA, low-dose GCA, and placebo. Subjects were divided into 3 even smaller groups, but not by treatment: Instead, each group took all 3 treatments, for 6 weeks at a time, with a 2-week rest period in between. The only difference between the groups was the order of the treatments (high dose/low dose/placebo). Subjects in all 3 groups lost approximately the same amount of weight. What was the difference? Well, the authors claimed that the amount of weight loss during the periods when the subjects were taking GCA was greater than when they weren’t, even though they lost weight even during placebo treatment.
One criticism of the study is that there was no adequate placebo control. Looking at the document, it is impossible to say how much weight loss is attributed to green coffee beans rather than daily dietary following, which is known to help with weight loss. And it’s a very, very small studio.
Perhaps a bigger problem is that the trial was conducted in India and then written by an American researcher, Joe Vinson of the University of Scranton, as revealed by a story on The balloon and the mail (Canada) last December. That’s right: the subjects were recruited in India, all the data was collected there, and the data was emailed to Vinson so he could write it down.
Even more troubling was that the creators of GCA paid Vinson to write the study. Worse yet, the document states that “the authors report no conflicts of interest in this work.” When asked about this by The balloon and the mail:
“Vinson said he doesn’t win financially if the company sells a lot of products, and the magazine didn’t require him to disclose the relationship.”
This poorly conducted little study was anything but “amazing,” as Dr. Oz called it. I have little confidence that the data sent to Vinson from India was correct.
Perhaps Dr. Oz was also concerned, because a few months after his original show, he did another show where he retested green coffee bean extract. He said that he was responding to criticism from the previous show of him and that he wanted to set the record straight. For his second show, “Green Coffee Bean Extract: The Answer to Weight Loss?” he performed his own experiment:
“For the first time, we are doing an unprecedented experiment,” he said. “We’re doing our own study, right here on this show…the first of its kind on TV!”
Oz’s experiment involved 100 women, all of whom were in the studio audience for his show, who took either green coffee bean extract or a placebo pill for two weeks. And the result? I won’t make you watch the video; here is the full statement of results, from Oz’s website:
“In two weeks, the group of women taking the green coffee bean extract lost, on average, two pounds. However, the group of women taking the placebo lost an average of one pound, possibly because they were more aware of their diet during those two weeks because of the food diary required.”
On the show, Oz proudly stated, “The green coffee bean worked for us.”
Perhaps Dr. Oz’s science experiment was better than Vinson’s study. But that doesn’t mean it was good. First of all, Oz seems to have ignored some critical rules about how to conduct an experiment on humans. As Scott Gavura pointed out on the Science-Based Medicine blog, Oz’s study “makes a mockery of good research methodology.” Oz did not explain how the women were recruited for the experiment, and Gavura points out that Oz did not obtain the ethics board approval that all human subject experiments require.
Oz also seems to deliberately ignore the notion that 2 weeks is too short a time to assess the value of a weight-loss treatment. Will he go back to those same women a few months later to see if the effect lasts? Somehow I doubt it.
But what about that result? The women who took the coffee bean extract lost 2 pounds, compared to just 1 pound for the other group. (Actually, thanks to Scott Gavura, we know the difference was even smaller, just 0.76 pounds.) Oz does not provide any statistical analysis to show that this difference is even marginally significant. He also does not provide the raw data that would allow others to replicate his analysis, as he might have to do if he really intended to publish his study. But for Oz, what he described on his show seems to be proof enough. That’s a poor excuse for science.
Meanwhile, sales of green coffee bean extract continue to rise. My advice: save your money. And the next time Dr. Oz performs a science experiment, he’ll be skeptical.