His credentials are impressive: Vice-Chairman, Department of Surgery, Columbia University College of Physicians and Surgery; he has a long list of publications; and he holds three degrees from Ivy League Colleges. He’s also won a few Emmys and was one of the Time 100, The World’s 100 Most Influential People, in 2008.

Yet Dr. Oz, host of The Doctor Oz Show  since 2009 and The Doctors doesn’t do so well when it comes to fact checking. Following a June 2014 Senate subcommittee hearing in which he was taken to task for unsubstantiated claims made on his show, a group of Canadian researchers and physicians fact checked many claims he has made on his shows.

Researchers randomly selected 80 claims from each show and looked to see what evidence, if any, could back them up. Two team members conducted independent searches, spending up to an hour on each one. “In an attempt to be as fair as possible” to the shows, they wrote, they “used a relatively broad definition of support.” Still, only 21% of the recommendations on “The Dr. Oz Show” could be supported by what the researchers considered “believable” evidence. Another 11% were supported by “somewhat believable” evidence. Given that his shows’ viewership averages just under 3 million people per day, that’s a lot of people being exposed to a lot of apparently unsubstantiated medical advice.