Can you trust Dr. Oz? His medical advice often conflicts with the best science.

Dr. Oz’s Miracle Diet Advice Is Malarkey

Dr. Oz’s Miracle Diet Advice Is Malarkey

Health and medicine explained.
Jan. 1 2013 10:08 AM

Dr. Oz’s Miraculous Medical Advice

Pay no attention to that man behind the curtain.

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Much of what Oz says about high-calorie foods, exercise, even teeth flossing, isn’t bad at all.

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, 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 Vs. Evidence





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).

- Multiple systematic reviews found conflicting results on the effect of probiotics on colitis (Dendukuri et al. 2005; McFarland 2006; Pillai & Nelson 2008).


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).



Julia Belluz is the Science-ish blogger, a senior editor with the Medical Post, and contributing writer for Maclean’s magazine.

Steven J. Hoffman is an assistant professor at McMaster University and the McMaster Health Forum, a Trudeau Scholar, and an instructor at the Harvard School of Public Health.