It's not hard to understand what makes Dr. Oz so popular. Called "America's doctor," syndicated talk-show host Mehmet Oz speaks in a way anyone can understand. Medicine may be complex. But with Dr. Oz, clad in scrubs and crooning to millions of viewers about "miracles" and "revolutionary" breakthroughs, it's often not.

"I haven't seen a doctor in eight years," The New Yorker quoted one viewer telling Oz. "I'm scared. You're the only one I trust."

But is that trust misplaced? Or has Oz, who often peddles miracle cures for weight loss and other maladies, mortgaged medical veracity for entertainment value?

These questions have hammered Oz for months. In June, he was hauled in front of the U.S. Congress, where Sen. Claire McCaskill told him he gave people false hope and criticized his segments as a "recipe for disaster." Then last month, a study he widely trumpeted lauding coffee bean weight-loss pills was retracted despite Oz's assertions it could "burn fat fast for anyone who wants to lose weight."

And now, his work has come under even greater scrutiny in the British Medical Journal, which on Wednesday published a study analyzing Oz's claims along with those made on another medical talk show.

What they found wasn't reassuring.

The Canadian researchers, led by Christina Korownyk of the University of Alberta, charged medical research either didn't substantiate — or flat out contradicted — more than half of Oz's recommendations.

"Recommendations made on medical talk shows often lack adequate information on specific benefits or the magnitude of the effects of these benefits," the article said. "The public should be skeptical about recommendations made on medical talk shows."

Oz, for his part, said he's only trying to give people all the options out there. He said data shouldn't stop patients from testing out things like raspberry ketone — a "miracle in a bottle to burn your fat" — even if it's never been tested on people, according to Slate.

"I recognize that oftentimes they don't have the scientific muster to present as fact," Oz said at a U.S. Senate hearing, adding that he "personally believes in the items I talk about in my show.

"But, nevertheless, I give my audience the advice I give my family all the time. I give my family these products, specifically the ones you mentioned. I'm comfortable with that part."

But the Canadian researchers weren't nearly so comfortable. They selected 40 episodes from last year, identifying 479 separate medical recommendations. After paging through the relevant medical research, they found evidence only supported 46 per cent of his recommendations, contradicted 15 per cent and wasn't available for 39 per cent.

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The study was not without its limitations, however. The researchers conceded it was difficult to parse "what was said and what was implied." And some of the recommendations were extremely general — "sneezing into your elbow prevents the spread of germs" — and consequently difficult to find in medical research, let alone substantiate.

Still, the article was a withering assessment of Oz and the whole doctor talk show business.

"Consumers should be skeptical about any recommendations provided on television medical talk shows, as details are limited and only a third to one half of recommendations are based on believable or somewhat believable evidence," the paper said.

"Decisions around health care issues are often challenging and require much more than non-specific recommendations based on little or no evidence."

But Oz considers himself an iconoclast trying to shake up a stodgy medical community.

"Much of medicine is just plain old logic," he told The New Yorker. "So I am out there trying to persuade people to be patients. And that often means telling them what the establishment doesn't want to hear: that their answers are not only the answers, and their medicine is not the only medicine."

The study is part of an ongoing debate about medicine on television.

There's clearly a market for doctor talk shows. The Dr. Oz Show ranks in the top five talk shows in the United States, bringing in a haul of roughly 2.9 million viewers per day. And the talk show The Doctors, also studied in the paper, nets around 2.3 million viewers per show.

These days, Oz considers disease in terms of marketability. Cancer, he told The New Yorker, "is our Angelina Jolie. We could sell that show every day."

But some doctors have expressed alarm at Oz's willingness to sell it. "Although perhaps not as 'sexy' as Dr. Oz would like, the public needs more information about the effects of diet as a whole on cancer risk," commented one paper titled "Reality Check: There is no such thing as a miracle food" in the journal Nutrition and Cancer. It lambasted Oz's assertion that endive, red onion and sea bass can decrease the likelihood of ovarian cancer by 75 per cent.

"Mehmet is now an entertainer," New York doctor Eric Rose told The New Yorker. "And he's great at it. People learn a lot, and it can be meaningful in their lives.

But "sometimes Mehmet will entertain wacky ideas — particularly if they are wacky and have entertainment value."