Dr. Oz, you're not helping diabetics

Feb 24 2011 Published by under Medicine

Dr. Mehmet Oz is one of America's most influential doctors.  Just ask him.  He has a TV show and everything.  And in the past, much of his advice had been practical and mundane, the same advice you might hear from your own (perhaps less charismatic) physician.  But lately, he's been giving out frankly bizarre medical opinions.  Not all of Oz's recommendations are over-the-top strange, but even some of his less-bizarre stuff is hyperbolic to the point of being---in my opinion---deceptive.  Let's explore one example close to my heart, diabetes.  As an internist, one of my most important tasks is the prevention and treatment of diabetes.  I know something about it.  As a heart surgeon, Dr. Oz deals with one of the most serious complications of diabetes, coronary heard disease, so he must know a bit about it as well.

So I was a bit surprised to learn from his website that I've  been going after diabetes the wrong way.  Unknown to me is the "prevention powerhouse" of coffee and vinegar.  He recommends heavy consumption of these miracle foods to prevent diabetes and to help the liver and cholesterol, whatever that means.  Reading this, two questions come to mind (a few more, really, but two that we will focus on): is this plausible, and is this true?

There are a few epidemiologic studies that support the idea that coffee consumption is in some way associated with diabetes risk.  (For a bit of background on different types of studies, see here and here.)  There are a few bits of basic science that could explain this relationship, if it turns out to be causal.  But these large studies simply show relationships.  They have found that people who drink more coffee (regular or decaf) were less likely to develop diabetes during the study period.  Most of these studies tried to control for confounding variables (for example, caloric intake) but none of these truly shows cause and effects.

The two biggest potential problems here are recall bias and confounding variables.  Do people reliably report the data we ask them to?  We aren't directly measuring it, so this is critical.  Do coffee drinkers simply have smaller appetites?  Or other habits that reduce the risk of diabetes?  These studies give us an interesting starting point.  The next step to look for actual cause and effect would be a randomized controlled trial (which obviously could not be double-blind), that takes non-diabetics and randomly has half drink coffee and half abstain, and follows them over a several year period.   The idea that coffee can affect blood glucose metabolism and the development of diabetes is not nuts, but the available data don't allow us to go any further than that.

The data support the plausibility of the question of coffee and diabetes, but not the truth of the statement.   But let's pretend it is true.  The next questions are are how much risk reduction is there, and at what cost?

We know that some drugs and proper diet and regular exercise reduce the risk of diabetes.  How do these interventions compare with coffee or vinegar?  Is one of them 100 times more potent than the other?  One thousand?  One fifth?  And what are the hazards of caffeine consumption?  Not that great in general (and lessened by drinking decaf), but even small amounts of caffeine can cause significant acid reflux, sleep problems, heart palpitations, headaches.

What Dr. Oz is suggesting is using an unproven drug (coffee or dilute acetic acid) that isn't needed.  We have safe, effective ways to prevent diabetes.  Our biggest failure is in providing people with the education, health care, and other tools to follow through.


Salazar-Martinez E, Willett WC, Ascherio A, Manson JE, Leitzmann MF, Stampfer MJ, & Hu FB (2004). Coffee consumption and risk for type 2 diabetes mellitus. Annals of internal medicine, 140 (1), 1-8 PMID: 14706966

VANDAM, R., & FESKENS, E. (2002). Coffee consumption and risk of type 2 diabetes mellitus The Lancet, 360 (9344), 1477-1478 DOI: 10.1016/S0140-6736(02)11436-X

Tuomilehto, J. (2004). Coffee Consumption and Risk of Type 2 Diabetes Mellitus Among Middle-aged Finnish Men and Women JAMA: The Journal of the American Medical Association, 291 (10), 1213-1219 DOI: 10.1001/jama.291.10.1213

van Dam, R. (2006). Coffee, Caffeine, and Risk of Type 2 Diabetes: A prospective cohort study in younger and middle-aged U.S. women Diabetes Care, 29 (2), 398-403 DOI: 10.2337/diacare.29.02.06.dc05-1512

Pereira MA, Parker ED, & Folsom AR (2006). Coffee consumption and risk of type 2 diabetes mellitus: an 11-year prospective study of 28 812 postmenopausal women. Archives of internal medicine, 166 (12), 1311-6 PMID: 16801515

Dam, R., Dekker, J., Nijpels, G., Stehouwer, C., Bouter, L., & Heine, R. (2004). Coffee consumption and incidence of impaired fasting glucose, impaired glucose tolerance, and type 2 diabetes: the Hoorn Study Diabetologia, 47 (12), 2152-2159 DOI: 10.1007/s00125-004-1573-6

23 responses so far

  • Jason Evan Mihalko, Psy.D. says:

    Great article and a needed reminder that charisma alone does not mean we should believe what we hear. I think I know the various safe and effective ways to lower my risk of developing diabetes. I wish you would have added that information to this post so the casual reader had an opportunity to be exposed to that information.

  • Coffee as a cure gets ratings, telling some fatass to put down to 10th Mountain Dew can of the day, grab a bottle of water, and go for a walk isn't as sexy.

    But its the right thing to say.

  • DNLee says:

    Great post. Thanks for sharing PalMD. I will definitely pass along to my friens who watch that show.

  • Great. Another way to justify my addiction.

  • BB says:

    quote: We know that some drugs and proper diet and regular exercise reduce the risk of diabetes.

    Ther link isn't working; I'd like to read more on this topic, thanks.

  • becca says:

    Do such studies control for soda consumption?
    If we are looking at large populations that need a caffeine fix, and we find that the coffee drinkers have lower risk of diabetes than the mountain dew tards, I don't think that is really all that convincing coffee is great. On the other hand, maybe the mountain dew tards reading Dr. Oz would benefit form the advice?

    • chall says:

      I thought the same thing. People who like "regular brewed coffee" (i.e. not the milk frappe mocha suger stuff) might not be huge drinkers of soda... and afaik, soda has been indicated in occurence of diabetes...

  • Epicanis says:

    I hadn't heard the vinegar one before. This paper might be a start on where he's getting that (tenuous-sounding) connection:

    Liatis S, Grammatikou S, Poulia KA, Perrea D, Makrilakis K, Diakoumopoulou E, Katsilambros N:"Vinegar reduces postprandial hyperglycaemia in patients with type II diabetes when added to a high, but not to a low, glycaemic index meal."; Eur J Clin Nutr. 2010 Jul;64(7):727-32


  • The Blind Watchmaker says:

    Just finished an after lunch cup of Joe. Ahhh.

  • WhizBANG! says:

    The first lady is pushing proven remedies for obesity and, ultimately, diabetes: good eating habits and exercise, but the tea-bagger types decry that as "the guvment telling me what to do."
    Dr. Oz is a capitalist. I guess they want us to let the markets sort out what works in medicine.

    • Rob says:

      Except there's a difference between "educating me" on what I should and shouldn't be eating so I can make an informed choice... which sometimes may include things that aren't so good for me... and using laws to eliminate the choice in the first place.

  • Kathy says:

    Sigh. Oprah did incalculable damage letting Dr. Oz appear on her show last year as a "diabetes expert." I guess according to him, vinegar prevents organ failure too? (In the case of us type 1 diabetics out here)

    (By the way I am a case study in the preservative powers of caffeine, at least in Diet Coke form...28 years of the stuff and I'm neither dead of cancer nor cured of diabetes, but still hanging on to both eyes, kidneys and feet. Yay!)

    • OleanderTea says:

      " I guess according to him, vinegar prevents organ failure too?"

      Well, you could certainly use vinegar to preserve organs. Though "preservation" is probably not quite the same thing as "prevention". 😉

  • A. Marina Fournier says:

    Wasn't he suggested as a candidate for Surgeon General a couple of years back?

    I'm sorry, but "America's doctor" just retired: Dr. Dean Edell was a great debunker of medical fraud and quackery, woo, celebrity endorsements, and "alternative" medicine. He emphasized the importance of controlled, double-blind studies with a decent sized study population, with reproducible results. I miss his program, as it always gave me something to think about, and useful information. He would never have accepted this guy's "diabetes cure/control", but would have pointed out the fallacies and holes in logic & science.

    If asked, he was not interested in the post of Surgeon General...and his vice, or addiction, was coffee.

    He, too, held with the non-sexy view of "eat fewer calories than you use" in order to lose weight, but not to deprive yourself of foods you enjoy--just eat smaller portions of them. He thought well of Mrs. Obama's campaign.

    • Peggy says:

      Yes! Dr. Edell was a staple around my house growing up. He always seemed to give such reasonable sound advice.

      I caught a bit Dr. Oz's TV show and it was appalling. He was on an Oprah-like set, wearing scrubs for some reason, and shilling for some new cosmetic surgery procedure. Awful.

  • Katharine says:

    Dr. Oz's wife is a Reiki bullshit practitioner. Oz is a dumbass. News at 11.

  • OleanderTea says:

    I had to make my doctor's office turn off Dr. Oz that day, because in addition to giving out shite advice, he was causing my (low-normal) blood pressure to rise.

    I did point my doc in the direction of this blog for Pal MD's remarks about Dr. Oz. (Hi, Dr. Z!)

  • skeptifem says:

    I have heard a lot of ridiculous woo about food from doctors/nurses just walking around the hospital. From what I understand nutrition education on it isn't that great for MDs and RNs. Nutritionists aren't utilized as much as they should be.

  • CherylK says:

    Thank you for this article...I just get so disgusted when these types fall all over themselves once they hit the limelight. Dr. Oz and Dr. Phil are cut out of the same cloth, unfortunately.

    I'm not diabetic but it's in my genes and I'd like to keep myself healthy enough that I won't ever develop it. I don't need or want unreliable medical advice from show biz.

  • chall says:

    I guess most of everything is "quick fix" and "magic fix", not to mention sexy.

    The coffee-diabetes linkage is less proven than exercise-diabetes, so if he really wanted to 'help' he could repeat the boring "move your body" and "eat less to loose weight". I guess though, that doesn't give you endorsements from all the food producers or nutrition suppliment manufactorers?

  • Vicki says:

    If he must have endorsements, how about "get out there and walk" and look for a tie-in with a sneaker company?

  • [...] Oz and other medical charismatics love aphorisms.  They make good sound bites, they're easy and quick to read, and consumers love them, but cui bono?  Certainly not patients [...]