As people were getting ready for the holiday season and its accompanying waist expansion late last year, Dr. Mehmet Oz let viewers of his TV show in on a timely little secret. “Everybody wants to know what’s the newest, fastest fat buster,” said the board-certified cardiothoracic surgeon and one of People magazine’s sexiest men alive. “How can I burn fat without spending every waking moment exercising and dieting?”
He then told his audience about a “breakthrough,” “magic,” “holy grail,” even “revolutionary” new fat buster. “I want you to write it down,” America’s doctor urged his audience with a serious and trustworthy stare. After carefully wrapping his lips around the exotic words “Garcinia cambogia,” he added, sternly: “It may be the simple solution you’ve been looking for to bust your body fat for good.”
In Dr. Oz’s New York City studio, garcinia extract—or hydroxycitric acid found in fruits like purple mangosteen—sounded fantastic, a promising new tool for the battle against flab. Outside the Oprah-ordained doctor’s sensational world of amazing new diets, there’s no real debate about whether garcinia works: The best evidence is unequivocally against it.
The miracle cure isn’t really a miracle at all. It’s not even new. Garcinia cambogia has been studied as a weight-loss aid for more than 15 years. A 1998 randomized controlled trial looked at the effects of garcinia as a potential “antiobesity agent” in 135 people. The conclusion: The pills were no better than placebo for weight and fat loss.
More recently, a group of researchers summarized the evidence for this “breakthrough” extract in a systematic review of 12 randomized trials involving 706 participants. Some trials reported short-term slimming, but the overall effects were so small and most studies were so methodologically flawed that the authors were unable to conclude that garcinia extract has an impact on body weight.
One of those authors, Edzard Ernst, has dedicated his career to analyzing research on alternative and complementary medicine; he found that the supplement may be linked to adverse gastrointestinal effects. He told us, “Dr. Oz's promotion of this and other unproven or disproven alternative treatments is irresponsible and borders on quackery.”
Still, people march into pharmacies or their physicians’ offices every day asking for Dr. Oz-endorsed treatments—even when these treatments are backed by the barest of evidence or none at all. Oz’s satellite patients spend tremendous amounts of money on products he recommends, a phenomenon that has been dubbed the “Oz Effect.” After he promoted neti pots, for example, Forbes magazine reported sales and online searches for the nasal irrigation system rose by 12,000 percent and 42,000 percent, respectively.
Who can blame his viewers? Oz may be the most credentialed of celebrity health promoters. He’s a professor and vice-chair of surgery at Columbia University College of Physicians and Surgeons. He earned his degrees at Ivy League universities, namely Harvard and the University of Pennsylvania. He’s won a slew of medical awards (in addition to his Emmys) and co-authored hundreds of academic articles. He’s clearly a smart guy with qualifications, status, and experience. It’s reasonable to assume he is well-versed in the scientific method and the principles of evidence-based medicine. “Because he’s a physician, that lends a certain authority and credibility to his opinions,” said Steven Novella, a clinical neurologist and assistant professor at Yale University School of Medicine who has taken Oz to task for his science. “But it lends credibility to anything he says.”
And lately, a lot of what Oz has been saying is downright wrong (scroll to the end if viewing as a single page).
To support the awesome assertions about the flab-fighter Garcinia cambogia, the doctor created on his TV show an atmosphere of accessible scientific certainty. He brought out researchers and physicians in white coats who discussed what they said was compelling evidence for the weight-loss panacea. There was an inspiring testimonial from a member of the audience. Plastic models even demonstrated how garcinia could suppress appetite and stop fat from being made. The show had the same easy manner as Oprah discussing Leo Tolstoy with her book club.
Throughout the episode, Oz maintained his trademark boyish wonder and excitement as he delivered a message many of us long to hear: A pill could help us “burn fat without spending every waking moment exercising and dieting” and even combat “emotional eating.” Oz peppered his excitement with some caution: “Please, listen carefully,” he said with a shrug of his shoulders and his hands raised defensively in the air, “I don’t sell the stuff. I don’t make any money on this. I’m not going to mention any brands to you, either. I don’t want you conned.”
Oz has acknowledged on air that as soon as he mentions a product, manufacturers clamor to get up websites claiming their brand was endorsed by him. They put his face on pill bottles and placards in health-food stores. They link to his show’s website and columns. His PR man, Tim Sullivan, told us that with every product Oz talks about, “the next morning I wake up to 50 Google alerts from companies saying ‘Oz recommends raspberry ketones.’ ” He says Oz’s legal team prosecutes these unauthorized endorsements “aggressively.”
Still, Oz seems to have a penchant for peddling products. Millions follow his advice through the TV and radio, as well as his books, newspaper columns, and magazine articles. And examples of his pseudoscience abound.
Take a breaking-news segment about green coffee-bean supplements that “can burn fat fast for anyone who wants to lose weight.” Oz cited a new study that showed people lost 17 pounds in 22 weeks by doing absolutely nothing but taking this “miracle pill.”
A closer look at the coffee-bean research revealed that it was a tiny trial of only 16 people, with overwhelming methodological limitations. It was supported by the Texas-based company Applied Food Sciences Inc., a manufacturer of green coffee-bean products. Oz didn’t mention the potential conflict of interest, but he did say he was skeptical. To ease his mind, he conducted his own experiment: It involved giving the pills to two audience members for five days and seeing what would happen. Unsurprisingly, both women reported being less hungry, more energetic, and losing two and six pounds, respectively.
There are many reasons why this made-for-TV “study” would not be published in any reputable medical journal or meet the approval of Oz’s peers: The sample size was minuscule. The women were not followed for long enough to know whether the effects of the supplement were real. They were neither randomly selected nor unaware of what they were taking. They also knew they were going to have to announce their weight in public to millions of viewers. That pressure, combined with a strong placebo effect, was the most likely cause of their shape change, if one can call it that at all.
As another example, for Day 6 of his “7-Day Miracle Plan to Boost Your Metabolism,” Oz told viewers “zinc reduces hunger by increasing your level of leptin” and that they might take 12 to 15 mg of the mineral daily. He probably based his claims on a study of mice that raised a possible link between zinc, leptin, and weight loss.
But experiments involving people don’t bear this out. A double-blinded, randomized, controlled trial in humans found that zinc supplements did not cause significant changes in weight, body mass index, body fat percentage, or waist circumference. Nor did leptin increase. One study suggested zinc may even lower leptin levels.
On a Jeopardy-themed episode about the “best flat-belly foods of all time,” Oz shared advice on what to do to get rid of a “muffin top.” He recommended almonds, yogurt, and olives, which he said are “great for keeping your belly flat.” Besides the fact that consuming any of these high-calorie foods in excess will do the opposite of keeping a person slim, there’s also no good evidence for targeted fat loss such as shedding love handles, especially by eating particular foods.
He has recommended fish oil supplements for improved cardiovascular health and vitamin D to stave off colon, prostate, and breast cancers and to slow aging. While some evidence supports the importance of fish and vitamin D in the diet, studies on supplements have not shown protective effects.
Oz calls raspberry ketone supplements another “miracle in a bottle to burn your fat.” Again, there’s no proof for this claim. All studies on raspberry ketones have been conducted on rodents or cells, never in people. At the end of a blog post on ShareCare, the website for “quality healthcare information” that Oz co-owns, even he concluded: “Positive early results in the lab can be promising, but these do not always mean the same outcomes will occur in humans.”
Sullivan, Oz’s PR representative, tried to soften the claims. He explained, “An adjective like ‘miracle’ is used as an editorial device to describe anecdotal results, as exemplified by the guests on our show. Our audience are not scientists, and the show needs to be more lively than a dry scientific discussion.” Even with the multiple warnings, the little miracles flew off store shelves.
A legion of doctor-bloggers has dedicated thousands of hours to dissecting and debunking Oz’s claims. One of them is Steven Charlap, a preventive medicine physician in Delray Beach, Fla. “Patients were bringing in shopping carts full of different pills,” Charlap recalls. “When I would ask them, ‘Why do you take a certain pill?’ I found very often, the response was, ‘I heard about it on the Oz show.’ ”
To understand where his patients were getting their health advice, Charlap began watching the program. “I was shocked that someone with his credentials—someone who apparently still operates on patients and therefore must still be fully cognizant of a physician’s first priority, which is to do no harm—would be recommending all types of different pills, many that had never undergone rigorous scientific scrutiny, as miracle cures or magic pills to a very susceptible audience.”
One of the first Oz-approved products Charlap looked into was milk thistle. Oz suggested the supplement as a “quick fix” for nights when you have one too many gin and tonics. The herbal remedy, according to Oz, “boosts your liver’s enzyme function, which helps to detoxify the body from excess alcohol.”
But Charlap noted that while some studies suggest milk thistle may be helpful for people with liver disease, the evidence is unclear on its other health benefits. So when a woman on milk thistle came into Charlap’s clinic for her annual wellness visit, he asked if she had any problems with her liver, an abnormal liver-function test, or any other medically justifiable reason for using the product. The answer was no: She used milk thistle because her “other doctor” told her to do so. She was taking Oz’s medicine.
Oz, Charlap noted, has also encouraged people to take two baby aspirin every night before bed to prevent heart attacks. For people at high risk for coronary heart disease, the authoritative U.S. Preventive Services Task Force would agree with him. But for healthy and older folks, aspirin can have damaging side effects—including bleeding ulcers—which are well-documented and may outweigh any potential benefits. Aspirin can also hurt patients who are on anti-coagulants or who have a history of gastric or stomach ulcers, a warning Oz does not mention on his show. An exasperated Charlap asked: “Where is the ‘first, do no harm’ when he does something like that?
Beyond potential damage to people’s health and purses, this kind of peddling can also foster doubt and mistrust of science. As Edzard Ernst put it: “Prominent people like Oz do have considerable influence. If this influence is used to promote quackery, bogus treatments will seem credible. Using bogus treatments for serious conditions may cost lives.”
Interestingly, for all the health wonders he promotes, Oz himself doesn’t rely on magic pills or quick fixes to maintain his salubrious air. He monitors his weight and exercises daily. According to a New York Times profile, his diet consists of berries, spinach, raw walnuts (soaked in water to “amplify their nutritional benefit”), and a dark green concoction of juices from cucumber and parsley. The Times journalist called it “the most efficient, joyless eating I have ever seen.”
This doesn’t make for good TV, though, which gets at the tension between the worlds of science and entertainment. Science is a process, moving along in increments, with stops and starts, mostly very slowly. As a result, new treatments are usually only slightly better than older ones, actual breakthroughs are rare, and good medicine is often dull. Showmen like Oz, however, must be anything but humdrum—five times every week.
When speaking to us for Maclean’s magazine last year before a Toronto appearance, Oz said he has to mix the low and high, hope and reality, to make sure he attracts enough viewers to stay on the air. He offered raspberry ketone supplements as an example of how he tries to give people hope. “I do actually believe from the data we have so far it could be a nice little nudge. The amount of weight you’ll lose is two, three, four pounds more than you would have. But it’s a nudge.”
He continued: “If you went line by line through the show and try to figure out what part of it is glitzy stuff, like icing on the cake, and what part is the meat of the cake, I bet that’s the right ratio: Three-quarters is meat and potatoes, hard-core stuff you got to do, but that’s the medicine.”
But as Novella noted, “I can see how it’s challenging to put out as many shows as he’s doing—that’s his problem. It’s his job to do that and have minimal standards.”
Why Oz would promote junk also raises questions about his links with industry. Though Sullivan maintains Oz has “no financial or business ties to any companies that make any retail product, including any that appear on the show for routine coverage,” he is not without at least indirect financial rewards for some of the health products and information he shares.
He promotes and is a scientific adviser for the website RealAge.com, which helps people calculate their body's age and promotes better living through nonmedical solutions. Yet, according to a New York Times investigation, “Pharmaceutical companies pay RealAge to compile test results of RealAge members and send them marketing messages by e-mail.” A seemingly benevolent health website has helped line Oz’s pockets through behind-the-scenes links to industry—and has Oz acolytes unwittingly handing over their personal health information to pharma.
Oz wouldn’t be the first celebrity physician to promote bogus medicine for personal gain. In 2012, it was revealed that CNN medical contributor Dr. Drew Pinsky—a board-certified addiction specialist—was paid by GlaxoSmithKline to encourage the off-label use of the antidepressant Wellbutrin. Pinsky once said on-air that the drug might help women achieve more orgasms during intercourse—a suggestion that set GlaxoSmithKline off with delight. According to an internal memo, the TV doc had successfully “communicated key campaign messages” to his massive audience. Apparently he performs well.
So how are we supposed to tell medicine from miracles? As a general rule, said Victor Montori, an evidence-based medicine guru at the Mayo Clinic, “If studies are cited, then this cannot be, at the same time, a secret revealed just to you now. If the studies are any good, the effects are usually very small.” Referring to Oz’s holiday weight-loss advice, he added: “It is very unlikely that an important compound hidden in the garcinia could have a big effect.”
We can also arm ourselves with the knowledge that not all evidence is created equally, and celebrities—even famous doctors—are not credible sources of health information.
Some other rules for sifting nuggets of good evidence from gobbledygook include: Research involving humans is typically more relevant than animal models; prospective, randomized, controlled trials are usually better than retrospective, observational analyses; large studies are better than small studies; multisite studies are better than single-site; and systematic syntheses of all the available evidence are more informative than individual studies presented out of context.
Our own doctors will probably know more about what’s good for us than our favorite celebrities, their doctors, or even America’s doctor, the wonderful wizard that is Oz.
DR. OZ'S RECOMMENDATION
BEST AVAILABLE RESEARCH EVIDENCE
DO THEY MATCH?
Take zinc (12-15 mg) daily for weight loss because it reduces hunger by increasing levels of leptin, a key hormone that alerts the body when it is full.
- A randomized controlled trial of 56 obese women found zinc supplements caused no significant changes in weight, body mass index, body fat percentage, waist circumference, or leptin levels (Marreiro et al. 2006).
- A randomized controlled trial of 40 obese women found zinc supplements had no effects on body mass index or waist circumference; the only effects found were increased zinc in blood serum and urine (Kim & Lee 2012).
- A retrospective cross-sectional study of 580 women found zinc was not associated with obesity or leptin levels in the overall population; in obese women, zinc was associated with lower leptin levels (Garcia et al. 2012).
Take omega-3 fatty acid DHA (600-1000 mg) daily from fish oil supplements for many health benefits, including better cardiovascular health.
- Multiple systematic reviews found supplements and dietary sources of omega-3 fatty acid did not prevent cardiovascular problems, including stroke, heart attacks, and death; one review found a higher risk of adverse events with omega-3 fatty acid supplements because of gastrointestinal side effects (Kotwal et al. 2012; Kwak et al. 2012; Rizos et al. 2012).
Take vitamin D (400-1000 IU) daily to prevent various cancers, fight off colds, and slow down aging, along with a variety of other health benefits.
- Multiple systematic reviews found inconclusive evidence on whether vitamin D supplements prevent cardiovascular outcomes, cancer and mortality (Pittas et al. 2010; Elamin et al. 2011; Holick et al. 2011).
- A systematic review by the U.S. Preventive Services Task Force found vitamin D supplements had no effect on cancer risk; the Task Force recommended against daily supplementation with vitamin D at doses of up to 400 IU unless the individual is vitamin D deficient (Chung et al. 2011; Kuehn 2012).
Take probiotic supplements or fortified foods to regulate the amount of beneficial bacteria in the body, promote digestive health, and normalize bowel movements.
- A systematic review of 82 randomized controlled trials found probiotics reduced the risk of certain types of diarrhea, but the results of the trials varied widely (Hempel et al. 2012).
- Multiple systematic reviews found probiotics may help alleviate symptoms of irritable bowel syndrome, but positive effects are limited to certain strains and included trials that have methodological limitations (McFarland & Dublin 2008; Brenner et al. 2009; Hoveyda et al. 2009; Moayyedi et al. 2010).
Take a multivitamin daily to ensure getting enough essential vitamins and to prevent heart disease, breast cancer and colon cancer.
- Multiple systematic reviews found no meaningful benefits from taking multivitamins to reduce the risk of death and prevent various diseases, including cancers, cardiovascular diseases, cataracts, macular degeneration, and hypertension (Huang et al. 2006; Chan et al. 2011; Macpherson et al. 2012).
- A randomized controlled trial of 14,641 men found taking daily multivitamins very slightly reduced cancer risk but did not reduce cardiovascular events and death from cardiovascular causes or cancer (Gaziano et al. 2012; Sesso et al. 2012).
- A prospective cohort study of 182,099 participants found no significant associations between multivitamins and cardiovascular disease, cancer, or death from any cause (Park et al. 2011).
- A retrospective cross-sectional study of 38,772 postmenopausal women found a strong association between multivitamin supplements and increased risk of death (Mursu et al. 2011).