Many Americans get their health advice not from their doctor, but from daytime television. But how good are those recommendations?

Reporting in the BMJ, Canadian researchers analyzed two medical TV talk shows—The Dr. Oz Show and The Doctors—and found that only 46% of the recommendations on The Dr. Oz Show and 63% on The Doctors were supported by evidence. 15% of advice given on Oz and 14% of advice on The Doctors contradicted the available published evidence in journals.

“The bottom line message is for people to be really skeptical about the recommendations made on these medical television shows,” says study co-author Christina Korowynk, associate professor of family medicine at the University of Alberta. “They should look for more balanced information to be presented, and understand that they need all of that information in order to make an informed decision.”

They measured 80 major recommendations made on the two shows from January to May 2013 against evidence gleaned from published studies in medical databases. They looked at both consistency—how much the conclusion was supported by the studies—and believability, which included the quality, number and type of study.

On average, Korownyk’s group found that both shows mentioned how the advice might specifically help a person in only about 40% of the recommendations, and they mentioned the amount of benefit, another aspect of useful health advice, in less than 20% of recommendations. (Harms were mentioned in less than 10% of the recommendations, and costs in less than 15%). She says that without such information on how much benefit and harm a particular recommendation might have, it’s hard for people to make informed choices about whether the advice is right for them.

Korownyk and her colleagues aren’t the first to cast doubt on the quality of advice given on the shows. In June a Senate subcommittee heard testimony from Oz on false advertising of weight loss claims and Sen. Claire McCaskill queried the doctor about the statements he made on the show. “I do personally believe in the items that I talk about on the show,” he said at the hearing. “We have to simplify complicated information. We have to make the material seem interesting and focus on the ‘wow’ factor.”

Representatives for The Doctors said in a written statement to TIME: “The Doctors was never contacted about the study or the article. Our producers and doctors all do their due diligence to make sure information provided on the show is sound, relevant and timely—often debunking the myriad of medical myths that abound in the media and across the internet.”

Members of The Dr. Oz Show wrote: “The Dr. Oz Show has always endeavored to challenge the so-called conventional wisdom, reveal multiple points of view and question the status quo. The observation that some of the topics discussed on the show may differ from popular opinion or various academic analyses affirms that we are furthering a constructive dialogue about health and wellness.”

Korownyk acknowledges that the exact impact of television health advice isn’t clear, since the study didn’t investigate how many of the recommendations people adopted and whether they had an effect on their health. But the advice is clearly reaching people. “What we’d love to see is a process on these shows where the evidence is reviewed in a critical manner, and presented in a balanced, objective way so the audience can understand,” she says. “As physicians, we are moving toward that, and we’d love to see the broader television personalities doing the same sort of thing.”

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