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Medicine is hard and should be practiced with caution

It’s tempting to think that the practice of medicine should be simple and intuitive.  Unlike other sciences, we all have access to the basic materials—ourselves.  We feel that because we are intimately familiar with our bodies, we know a lot about how they work.  Unfortunately, it’s a little more complicated than that.  The biochemical processes walking around in this sack of meat are pretty complicated.  Learning these processes is important, but in medicine, it’s not enough.  If we have a hypothesis that some change in biochemistry will affect some disease, we must test this in groups of real people in well-designed clinical trials.  Or, we can use the Huffington Post method and  just make it all up.

The latest abomination is an article on diabetes, by Kathy Freston.  Bad information on diabetes is particularly dangerous.  The longer diabetes goes untreated, the higher the likelihood of complications.  When reading medical writing it’s important to evaluate the source.  The author of this article wrote a book called, The Quantum Wellness Cleanse which pretty much says it all. But is it really fair to judge someone on a crappy book title?

Well, yes, but more important is the crappy interview she conducts with Dr. Neal Barnard.  I have no way of knowing with absolute certainty whether Barnard is as dangerous a fool as he sounds, but I suspect so.  He and Freston promulgate a dangerously over-simplified view of diabetes.  

To review briefly, type II diabetes is common and deadly.  It affects around 20 million Americans and if poorly treated leads to stroke, kidney failure, heart attacks, amputations, and death.  There is some evidence that in societies where people are poorly nourished or subsisting on minimal calories, diabetes is less common.   The disease is highly heritable, and is not evenly distributed among ethnicities, with African Americans, Hispanics,  many Native Americans, and probably South Asians being more affected than whites.  The disease usually starts as resistance to insulin.  Pancreatic beta cells bravely try to keep up, but eventually crap out.  With early dietary intervention, diabetes can often (but not always) be controlled. Whether someone with diet-controlled diabetes is still a diabetic is not settled.  There is more to diabetes than high blood sugar.  We know that controlling blood sugar, cholesterol, and blood pressure in diabetics prevents devastating complications.  If a diabetic loses 20 lbs and has normal sugars, we know we’ve reduced their risk, but evidence seems to support the idea that they are still “diabetic”, at least from the perspective of risk.

Some diets may be more or less “diabetogenic”, but  in general, a combination of genes, increase caloric intake, and abdominal adiposity are the big baddies.  Early in the course of developing diabetes, before the beta cells give up, it is usually possible to reduce insulin resistance by losing weight.  There is no good evidence that one particular approach to eating can “cure” diabetes.

Getting back to HuffPo, Dr. Barnard makes the reasonable statement that our society’s increased caloric intake contributes to soaring diabetes rates, and talks about the complications of diabetes. He then goes on to fall for one of the most common types of pseudo-scientific thought—oversimplification:

Let me emphasize that this grim scenario does not have to occur. If an unhealthy diet is the cause, a better diet can provide the answer to this problem.

Well, yes, in many if not most type II diabetics, dietary changes and exercise can dramatically change the course of the disease—at least early on when the beta cells still work. But diet alone is not always sufficient to control diabetes, and it’s dangerous to imply that it is. From the rest of the interview, it’s apparent to me that Dr. Barnard either went to a different kind of medical school than I, or didn’t pay attention:

So long as your body’s insulin can escort glucose into the cells normally, diabetes will not occur.

That is a lovely fantasy, but not consistent with reality. He goes on to claim that fat intake is the cause of insulin resistance and that a vegan diet can prevent and reverse diabetes:

And we can go beyond prevention. When people who already have diabetes adopt a low-fat vegan diet, their condition often improves dramatically. In our research, funded by the U.S. Government, we found that a vegan diet is more effective than a traditional current diabetes diet, and is much safer than a low-carb diet.

The study to which he is presumably referring is interesting, but hardly groundbreaking. It compared a standard American Diabetes Association balanced diet with a vegan diet. Both groups did quite well, with the vegan group doing better by some measures. The study was randomized, but obviously not blinded, and patients developed their own diets with the help of dietitians. The diets were apparently not equally caloric and there was a large range of intake in both groups. Diabetic control measured by glycolated hemoglobin levels was not terribly impressive (p=0.091). By their own analysis, weight loss was more important than type of diet in determining improvement of diabetes.

While interesting, this is not a study on which to hang an entire medical philosophy. What troubles me about this article is that it creates/perpetuates a myth that diabetes (meaning type II diabetes) is always preventable and reversible with a particular diet.  While I’m very happy to have my patients change their diets for the better, to tell them that a particular diet is some sort of panacea is just untrue.  It is wrong.  It is a lie.   Diabetes is a serious disease, and anything that delays its proper treatment causes disability and death.  Dietary changes are an important component in a comprehensive diabetic treatment plan, but the evidence is insufficient to recommend one diet over another.

Posted in: Science and Medicine

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77 thoughts on “Medicine is hard and should be practiced with caution

  1. daijiyobu says:

    Per: “dietary changes are an important component in a comprehensive diabetic treatment plan, but the evidence is insufficient to recommend one diet over another.”

    What!?

    But, the N.D.s, who are “science-based” [;)], and therefore primary care scientific experts [;(], are always quoting:

    “let your food be your medicine, and your medicine be your food.”

    In fact — per ND D’Adamo — my blood type is O, and I’m a hunter and a fisherman.

    And my diet, therein, has been scientifically individualized:

    “[the Blood Type Diet is] the first science that understands you as a biochemical individual” (see http://www.dadamo.com/ ).

    Away with you, Dr. L., and your impersonal statistics and objective, impersonal data!

    This is my own personal science.

    -r.c. [who is being facetious in the above].

  2. echinopsis says:

    Without trying to sound like a dick, and I know what you’re getting at with the article, but when you say this:

    “dangerously over-simplified view of diabetes.”

    and then you say this:

    ” Pancreatic beta cells bravely try to keep up, but eventually crap out”

    Well, lets just say it stood out..

    Nice article. I’ve got diabetes and it’s made me realise I tended towards the view that a diet could be the solution.. Although I did realise that not for everyone.

  3. wertys says:

    The study referenced also only looked at a 22 week followup period (?why 22 weeks, why not make it 26, or 52 weeks). As we know from many other diet studies, extreme dietary changes like going vegan or Atkins etc tend to regress to the mean over the longer term as they are more difficult for the average punter to stick to. My immediate response to looking even just at the abstract is to ask for the 12-month followup data where I predict the vegan group results would tend to come back to the pack. Notably, both groups improved a useful amount, and the subgroup analysis was confounded by the fact that when trying to compare diabetic control they had to exclude those who had changed their medications, thereby reducing the sample size and possibly introducing a systematic bias into the sample selection.

    So I agree…interesting but hardly compelling research.

  4. wertys says:

    Having now looked at the study proper, the number of those who had their diabetic medications changed in the vegan group was 25/49 compared to 17/50 in the standard diet group. Strangely the authors don’t seem to acknowledge this is the writeup as a confounding factor. The difference seems to hint that more in the vegan group needed changes in their medication over the relatively short study period.

  5. Kausik Datta says:

    Peter,

    Diabetic control measured by glycolated hemoglobin levels was not terribly impressive (p=0.091).

    Not terribly impressive? Not impressive at all! Considering the large enough sample size (49 and 50) in each group, I would have expected the p to be lower than 0.05 for any meaningful conclusion about the difference to be drawn. Also, if the portion sizes were not controlled (as mentioned in the study), how does one compare the effects of the vegan diet versus the ADA diet on the glycemic index, given that caloric restriction and redistribution is one of the primary components of diabetic diets recommended in medical practice in many parts of the world?

  6. Peter Lipson says:

    Pardon my understatement.

  7. Joe says:

    Barnard is/was the head of the Physicians Committee for Responsible Medicine, an extension of PETA (no, not people eating tasty animals). Their role in life is to make us all vegans- health consequences be damned. http://www.ncahf.org/articles/o-r/pcrm.html

  8. Neal Barnard MD says:

    Thank you for this interesting discussion about the use of low-fat vegan diets for type 2 diabetes.
    The study design was a randomized 22-week trial of a low-fat, low-GI, vegan diet, compared with a diet appropriately individualized based on 2003 ADA guidelines. It included a 1-year follow-up. The study design called for medications to remain unchanged, except when adjustments were required for patient safety (eg, hypoglycemia). This is because, although medication adjustments are inevitable in any diabetes study lasting more than a few weeks, they are a confounder. As a result, the study results were reported both as intention-to-treat (without regard to medication changes) and then with separate analyses taking medication changes into account.
    Let me list the study reports below for interested readers:
    Findings after the 22-week trial:
    Barnard ND, Cohen J, Jenkins DJ, Turner-McGrievy G, Gloede L, Jaster B, Seidl K, Green AA, Talpers S. A low-fat, vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes. Diabetes Care 2006;29:1777-1783.
    Findings after an additional 1-year follow-up:

    Barnard ND, Cohen J, Jenkins DJ, Turner-McGrievy G, Gloede L, Green A, Ferdowsian H. A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-week clinical trial. Am J Clin Nutr 2009;89(suppl):1588S-96S.

    Effects of the intervention diet on macro- and micronutrient intake:

    Turner-McGrievy GM, Barnard ND, Cohen J, Jenkins DJA, Gloede L, Green AA. Changes in nutrient intake and dietary quality among participants with type 2 diabetes following a low-fat vegan diet or a conventional diabetes diet for 22 weeks. J Am Diet Assoc 2008;108:1636-45.
    Diet acceptability:
    Barnard ND, Gloede L, Cohen J, Jenkins DJA, Turner-McGrievy G, Green AA, Ferdowsian H. A low-fat vegan diet elicits greater macronutrient changes, but is comparable in adherence and acceptability, compared with a more conventional diabetes diet among individuals with type 2 diabetes. J Am Diet Assoc 2009;109:263-72.

    Genetic issues:
    Barnard ND, Noble EP, Ritchie T, Cohen J, Jenkins DJA, Turner-McGrievy G, Gloede L, Ferdowsian H. D2 Dopamine receptor Taq1A polymorphism, body weight, and dietary intake in type 2 diabetes. Nutrition 2009;25:58-65.

    Review of related research:
    Barnard ND, Katcher HI, Jenkins DJA, Cohen J, Turner-McGrievy G. Vegetarian and vegan diets in type 2 diabetes management, Nutr Rev 2009;67:255-63.
    Related study assessing the effect of a vegan diet on body weight, short-term:
    Barnard ND, Scialli AR, Turner-McGrievy G, Lanou AJ, Glass J. The effects of a low-fat, plant-based dietary intervention on body weight, metabolism, and insulin sensitivity. Am J Med 2005;118:991-997.
    Related study assessing the effect of a vegan diet on body weight, long-term:
    Turner-McGrievy GM, Barnard ND, Scialli AR. A two-year randomized weight loss trial comparing a vegan diet to a more moderate low-fat diet. Obesity 2007;15:2276-81.

    For readers who would like a book for laypersons, with diet guidance and recipes, let me suggest Dr. Neal Barnard’s Program for Reversing Diabetes (2007: Rodale, Inc., Emmaus PA). For those interested in a definition of the lay term “reverse” in relation to diabetes, let me quote the book’s introduction:
    What Does It Mean to Reverse Diabetes? Most people with diabetes find themselves on a road leading toward gradually increasing weight, slowly rising blood sugars, higher doses of medications, and worsening complications. Reversing diabetes means reversing this trend. If weight is an issue, it can come down—gradually, but decisively. Blood glucose values that have come up can also come down. Doses of medications that have risen again and again can come down, too. Symptoms, such as painful neuropathy—the nerve pains in the feet and legs—can improve and even disappear. Heart disease can reverse.
    Will the disease go away completely? Some people would argue that once a person has diabetes, he or she will always have diabetes, even if blood tests improve so much that the condition is no longer diagnosable. What they mean is that the genetic traits that made the type 2 diabetes possible do not go away. And type 1 diabetes requires continued insulin treatments, regardless of how well you adjust your diet.

  9. Why do I get the feeling that Dr. Barnard’s comment is a form letter? I guess that would be because it is. Hanging out with homeopaths doesn’t help his credibility, either.

  10. Peter Lipson says:

    Given that we’re not much for censoring around here, I’d hope for a better response.

  11. Kausik Datta says:

    *facepalm*
    The response from Dr. Barnard is the funniest I have seen in a while… It is almost as if he is a bot, crawling the net looking for references to his work – and then, BAM! He spams the thread with plugs to his own studies – without contributing anything meaningful to the discussion!!

  12. Calli Arcale says:

    Or, indeed, noticing that the discussion is largely negative towards his work…. If he was actually paying attention (rather than just deploying a spambot), you’d think he’d sound a bit less “thank you for agreeing with me”.

    “Hey, you’re talking about how stupid my advice is — maybe you’d like to read my book explaining this advice so you can find out how to control your diabetes!”

    *facepalm*

    You’d also think he wouldn’t refer to himself in the third person. Kind of a giveaway. Either he’s a pompous ass, or the post above is by a bot. Or, more likely, both.

  13. jmorrison says:

    Either a diet can cure/prevent type 2 diabetes or not. Medicine doesn’t seem to like getting its hands dirty at this level: the science is hopelessly confounded by other factors, and used or abused by people with a philosophical or financial agenda.

    If diet cannot prevent your islets from crapping out, then Lipson is correct to call the diet advice a lie.

    But if diet can prevent it, then it’s not a lie. And it would of course appear to be inevitable that some people’s beta cells crap out – because people regress to the mean in their diet and lifestyle, ie. it’s too much work, they’re too lazy or don’t care.

    If you lose your keys at night, it’s easier to look for them under the lamp-post than to look in the dark. It’s ridiculous for a skeptic to deduce that the key does not exist.

    Of course it’s reasonable to be skeptical of any individual study and there are counter examples to Barnard – e.g. Bernstein – a diabetic and physician (Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome: time for a critical appraisal.) A Cochrane review shows clinically significant A1c reduction with low GI diets. So there’s opposing theories and room for more scientific enquiry. It doesn’t sound like tooth fairy science.

    Either a diet works or it doesn’t. Is this some sort of metaphysically unknowable question, that we must necessarily remain silent on or one that we’re just too lazy to study and answer properly?

    “The evidence is insufficient to recommend one diet over another” huh? There’s insufficient evidence to recommend say, cutting out that 2 L bottle of Pepsi per day habit?? The evidence is insufficient, therefore the evidence does not exist, therefore do nothing.

  14. Dr Benway says:

    Yo Dr.Barnard –

    Those slim facts you be hypin’ all outta proportion so’s you can sell your food woo sure do sound sciency, imma let you finish…

    But Andy Weil be pimpin’ the SCIENCIEST medical pseudoscience of all time. OF ALL TIME!!!!!!!!

  15. Dr Benway says:

    “The evidence is insufficient to recommend one diet over another” huh? There’s insufficient evidence to recommend say, cutting out that 2 L bottle of Pepsi per day habit?? The evidence is insufficient, therefore the evidence does not exist, therefore do nothing.

    2 liters of Pepsi is about 1000 calories. That doesn’t leave much room in a weight-neutral diet for other food capable of providing all the nutrients a human body needs each day. So I’d have to say no, not a good idea.

    Note that crazy-assed amounts of Pepsi probably isn’t a feature of either the ADA or the vegan diet being compared above.

  16. Neal Barnard MD says:

    Wow, you guys are a tough crowd! My previous reply was not a form letter, and neither is this one. I was trying to overlook the sniping, in hopes that you might actually read one or two of our papers and discuss the research. But I see I’ve only fanned the flames of blogger discontent. May I suggest a bit more fiber in your diet?

    The key point is this: Diet plays an obviously important role in both the cause and treatment of diabetes. And it’s fair to say that diets based on portion control and carbohydrate-counting, while logically designed, have been less than satisfactory and are tough to sustain.

    Because low-fat vegan diets reduce body weight, improve insulin sensitivity, and have major cardiovascular benefits, we decided to test such a diet for type 2 diabetes. The NIH-funded trial we’ve been discussing was a head-to-head test of this diet versus a more conventional approach. Overall, the results favored the vegan diet. Some people did reduce or even eliminate their medications (although that was not the purpose of the study), which was remarkable because the average participant had had diabetes for 8 years prior to study onset. But we certainly did not claim that people with diabetes can simply throw away their medications. Medication adjustments, when needed, should be done by the treating clinician, of course.

    We have assessed the acceptability and sustainability of the diet, with favorable findings, as you’ll see in the references above.

    Regarding mechanisms, I suggest the possibility that a low-fat vegan diet reduces intramyocellular lipid (IMCL). Previous studies have shown that lipid accumulation in muscle cells is tightly linked to insulin resistance, that diet can influence IMCL, and, in particular, that vegans have less IMCL, compared with omnivores.

    To tackle your questions:

    I did not refer to myself in the 3rd person; my name is actually part of the title that Rodale chose for my book, humbling though that may be.

    For the person who objected to my working with a homeopath, the fact is that during some upcoming lectures in India (where western fast-food has invaded, with diabetes in its wake), a very kind and helpful homeopathic doctor has agreed to provide cooking instruction for our participants. I am grateful to her for doing so.

    I do think skepticism is healthy–essential, in fact. After all, we have seen all manner of diets offered over the years. However, it is also important to look with interest and a certain amount of kindness on efforts to improve diabetes management, and the diet we present appears to be an important step in that direction.

    I would suggest that you (1) read our research reports cited above, if you are so inclined, (2) try the diet as recommended to see what it is like, and (3) keep an open mind, particularly since the “side effects” of a well-planned vegan diet are healthful weight loss and lower cholesterol and BP.

    I hope you find these comments useful and will accept them in the spirit in which they are offered.

  17. xwolp says:

    As a diabetic myself I find it incomprehensible how people can advocate a low fat or vegan diet for diabetics:
    Obviously, reducing caloric intake for type II diabetics is in most cases a good idea… but slashing entire groups of food from their diets will only lead to further complications. Diabetics generally speaking already have issues with vitamins and minerals. Second, fat helps stabilizing blood glucose levels by slowing the uptake of carbs… a little egg or butter can go a long way in avoiding sugar spikes.

  18. Dr Benway says:

    Dr Barnard,

    From the review above:

    Diabetic control measured by glycolated hemoglobin levels was not terribly impressive (p=0.091). By their own analysis, weight loss was more important than type of diet in determining improvement of diabetes.

    Your vegan diet is no better than the ADA diet with respect to mean glucose levels.

  19. the bug guy says:

    [blockquote]The key point is this: Diet plays an obviously important role in both the cause and treatment of diabetes. And it’s fair to say that diets based on portion control and carbohydrate-counting, while logically designed, have been less than satisfactory and are tough to sustain.[/blockquote]

    And a more restrictive vegan diet would be easier to sustain?

    As a type II diabetic who has controlled the disease through the ADA diet for the last three years, I can say that I didn’t find it hard to follow.

    As for the canard about medicine not addressing this, I have to disagree. When I was diagnosed, my PCP sent me to a diabetes center where I worked with a dietitian to learn how to change my eating patterns. I brought my hA1C down and have kept it below 6.0 without ever needing medication.

  20. Neal Barnard MD says:

    Thanks for your follow-up questions.

    Regarding sustainability: We have examined the acceptability of vegetarian and vegan diets in individuals with heart disease, diabetes, dysmenorrhea, and weight problems. In comparison with other therapeutic diets (eg, diets following ADA or National Cholesterol Education Program guidelines), vegan diets achieve much greater nutrient intake changes, while being similar in acceptability. A surprising finding, I know.

    The reason people adapt well to what one might imagine to be a restrictive diet seems to be that (1) they can eat as much as they want without calorie limits, (2) they do not have to restrict carbohydrate, (3) their tastes change, rather like an ex-smoker who no longer cares for cigarettes, (4) they like the benefits (weight loss, etc.), and (5) the diet really doesn’t feel so restrictive when people realize the range of foods it includes.
    We also try to make the transition easier with free online videos and support. If you’re interested, you’ll see them at http://www.pcrm.org.

    Regarding P-values: You are correct that the A1c drop was non-significantly greater for the vegan group, compared to the ADA group in the intention-to-treat analyses. In analyses adjusted for medication changes, the A1c reduction was significantly greater in the vegan group.

  21. the bug guy says:

    (1) they can eat as much as they want without calorie limits

    And then,

    (4) they like the benefits (weight loss, etc.),

    What?

    Are you really trying to say that vegan diets don’t follow Conservation of Mass/Energy?

    It sounds like any of the hundreds of other fad diets out there.

  22. Dr Benway says:

    Bug guy,

    There are two solutions to the apparent contradiction between, “they can eat as much as they want without calorie limits” and the law of conservation of matter and energy. You focused on one solution: bending the conservation law. The other solution hides inside the phrase, “as much as they want.”

    Regarding P-values: You are correct that the A1c drop was non-significantly greater for the vegan group, compared to the ADA group in the intention-to-treat analyses.

    And this is why I feel you overstate your data when you pimp the vegan diet as if it had special powers to fix diabetes. Honesty ought to force you to say, “Both the vegan diet and the ADA diet can be helpful for diabetics.”

    I understand and sympathize with your concern for how humans treat other animals. I wake up most mornings to the sound of idiots shooting at the four terrified mallards remaining on our pond. Those ducks are clever, social, playful, and capable of mentalizing.

    But good science means seeking what is true above every wish, above all else.

    In analyses adjusted for medication changes, the A1c reduction was significantly greater in the vegan group.

    Did you control for multiple comparisons?

  23. Dr Benway says:

    I should have broken my post into two parts. The top bit is for the bug guy and the bottom bit for Dr. Barnard.

  24. the bug guy says:

    Dr. Benway, I get what you mean, but I think we can both agree that when given the chance to eat as much as they want, people rarely are able to keep their caloric intake below expenditure.

    Because of that, I think that it is disingenuous to make such a presentation.

  25. Steve H says:

    I would avoid staking any claims based upon using that particular analyzer for measuring HbA1c. It was not known for generating results that favored comparably to the standard measurement techniques. In fact, I don’t even know if the IMX reagents were still being sold at the time of the study. The College of American Pathologists HbA1c/GHB proficiency program last had results for the IMX in 2002, with 8 labs reporting results. The prior year, the method had enough labs to generate a field CV of over 7%, compared to below 3% for contemporary HPLC instruments. In 2000, Abbott was granted FDA approval for a replacement reagent set for the IMX platform to measure HbA1c, and it was considerably better. However, the second generation, from my understanding, never was actually marketed.

    We now know that losing weight, which the vegan dieters did more of, results in lower A1c. In other words, there might be the suggestion that a vegan diet would be better, but we would need more definitive data. Additionally, we would need to know if merely showing a preference in diabetes education for the vegan diet would result in lower rates of compliance.

  26. Rob Tarzwell says:

    Given that both ADA and vegan diets can help control diabetes, even to the point of dietary control being sufficient, I don’t get all the vegan-diet bashing.

    If a vegan patient came into my office and asked, “Is a vegan diet consistent with good diabetes control,” I could honestly and ethically say “Yes.”

    This *opens* the range of dietary options for diabetic patients. Isn’t that a good thing?

  27. Peter Lipson says:

    Probably…that’s not what the original article said, however.

  28. Dr Benway says:

    This *opens* the range of dietary options for diabetic patients. Isn’t that a good thing?

    I missed the “vegan-diet bashing.” I thought the point was overstating the data.

    But just for fun I can bash veganism, if you please.

    A vegan diet is like a tiny sub-set of an ADA diet. So if I were a patient, I’d hardly feel my choices expanded by adding veganism.

    For me the hardest part of veganism would be no cheese.

    NO CHEESE!!! OMGWTFBBQ!!!!!!!!!!!!!

    A fat brie wheel and a loaf of sourdough, blue cheese on spinach, a cracker with white cheddar so sharp you must sit down, camembert on an apple slice, thinly sliced swiss on rye, grated asiago on toast… what is life without these things?

  29. Rob Tarzwell says:

    Peter,

    Are you referring to the HuffPo interview, or to Barnard’s study? The study itself makes no grandiose claims, and I see no evidence that Dr. Barnard is a “dangerous fool.”

    One of the interesting findings of the Barnard study was that subjects found adherence to a vegan diet easier than to the ADA diet.

    Given the crucial role of diet in diabetic management, that’s a finding worth pursuing with broader studies. Weight loss and lipids can be reduced by diet, along with improved insulin sensitivity.

    If that diet can be constructed where adherence is significantly improved, this is a finding of crucial importance to public health.

    That is “dangerous foolishness” I can get behind.

  30. Dr Benway says:

    Why would it be easier to stick to a vegan diet? It’s more restrictive than the ADA diet.

  31. Rob Tarzwell says:

    Dr. Benway,

    I don’t know why it would be easier to stick to a vegan diet, but the data speak, and we should listen.

    Also, mea culpa, the Barnard study does break down all groups in separately linked tables which I did not see in my initial reading of the study.

  32. Dr Benway says:

    Hey, cool. I like it when the data speak.

    But when the data refuse to answer my perfectly reasonable, common-sense questions, I bring out the waterboard.

  33. Rob Tarzwell says:

    Dr. Benway,

    Thanks for sending me that link. I hope you aren’t surprised when I am not persuaded by an exquisitely sensitive, flamboyantly non-specific study.

    Let me attempt to answer your “perfectly reasonable, common-sense question.”

    First, I answer a question with a question: why on earth would you consider a vegan diet to be merely a more restricted version of the ADA diet? This suggests to me, frankly, that your notion of a vegan diet is almost hopelessly unsophisticated. I suspect your version of veganism is “meat and potaotes” minus the meat. It wouldn’t surprise me at all if not a single patient in your distinguished career has ever approached you for advice about a plant-based diet.

    Second, let me supply a positive answer. The vegan diet, as broadly construed, is far wider than the standard North-American diet. Most of our countrymen haven’t the faintest idea what a legume is, let alone how it ought to be prepared and consumed. I suspect this hunch is broadly generalizable to such exotics as beans and lentils.

    Another way of saying this is, most of our kin and patients consider the vegan diet to be what remains on the typical meat-greens-starch plate once you take away the meat. This simply isn’t the case. I agree immediately that such a diet would be restrictive and boring. For those who delve into the further reaches of veganism, such as legumes, beans, and lentils, this simply isn’t relevant, and the options of diet expand in directions which we fussy physicians don’t typically even consider.

    Please put away your waterboard and consider the possibility that there are non-radical ways of construing diet which are, nevertheless, fundamentally different from yours.

  34. Dacks says:

    Rob,
    I don’t think anyone here is trying to bash a vegan diet or argue that it can’t be a full and satisfying choice. It seems to me the point being made is that all the food choices in a vegan diet are encompassed in the ADA recommended diet, but the standard diet also includes other healthy foods, such as lean meat, etc. The vegan diet is more limiting simply because it contains only a subset of the available foods.

    My own diet is largely vegetarian, with plenty of legumes, leafy greens and fruit. We only began incorporating more animal products into our diet because my kids got tired of the rice and beans. Hubby and I are looking forward to when they leave home so we can eat all the good foods we like – mushrooms, peppers, polenta – without “issues.”

    One legacy I have passed on to my kids – they love tofu. A tofu and veggie stir fry w/ rice is comfort food in our house!

  35. Joe says:

    @Dacks,

    You can serve your kids meat without partaking of it yourself. My sister-in-law used to do that.

  36. Scott says:

    Rob,

    Recheck your thinking. It’s true that many people underestimate the choices in a vegan diet, but those same things lead them to equally underestimate the choices in the ADA diet. It does not lead to a relative advantage for the vegan diet, which remains strictly more restrictive.

  37. Peter Lipson says:

    The issue, though, is not the relative merits of these diets, but whether the data support extravagant claims about them.

  38. Dr Benway says:

    …why on earth would you consider a vegan diet to be merely a more restricted version of the ADA diet? This suggests to me, frankly, that your notion of a vegan diet is almost hopelessly unsophisticated. I suspect your version of veganism is “meat and potaotes” minus the meat…

    The vegan diet, as broadly construed, is far wider than the standard North-American diet. Most of our countrymen haven’t the faintest idea what a legume is, let alone how it ought to be prepared and consumed. I suspect this hunch is broadly generalizable to such exotics as beans and lentils.

    Good lord. You think associatively like an advertising agent rather than categorically or logically like a scientist.

    The ADA diet involves portion control and carbohydrate counting. It’s not concerned with where the carbohydrates or other macronutrients arise. A vegan diet, on the other hand, is restrictive of macronutrient sources.

    Thanks for sending me that link. I hope you aren’t surprised when I am not persuaded by an exquisitely sensitive, flamboyantly non-specific study.

    You described Ioannidis’classic paper as a “study,” which means that either you didn’t read it or you are retarded.

    Much to learn have you, young padawan.

  39. Dr Benway says:

    Oh bugger on the blockquotes. I want to be clear so I’ll repost and hopefully someone can delete the earlier fail version.

    …why on earth would you consider a vegan diet to be merely a more restricted version of the ADA diet? This suggests to me, frankly, that your notion of a vegan diet is almost hopelessly unsophisticated. I suspect your version of veganism is “meat and potaotes” minus the meat…

    The vegan diet, as broadly construed, is far wider than the standard North-American diet. Most of our countrymen haven’t the faintest idea what a legume is, let alone how it ought to be prepared and consumed. I suspect this hunch is broadly generalizable to such exotics as beans and lentils.

    Good lord. You think associatively like an advertising agent rather than categorically or logically like a scientist.

    The ADA diet involves portion control and carbohydrate counting. It’s not concerned with where the carbohydrates or other macronutrients arise. A vegan diet, on the other hand, is restrictive concerning the sources of macronutrients.

    Thanks for sending me that link. I hope you aren’t surprised when I am not persuaded by an exquisitely sensitive, flamboyantly non-specific study.

    You described Ioannidis’classic paper as a “study,” which means that either you didn’t read it or you are retarded.

    Much to learn have you, young padawan.

  40. Dacks says:

    Joe,
    Yes, but I think you then have the situation that Rob was setting up – taking away the protein from a meal without replacing it with another source. A vegetarian or vegan meal might include several lower quality protein sources rather than one high quality source, so swapping out might not work.

  41. Dacks says:

    Joe,
    Besides, I love a piece of (pasture raised, grass-fed, locally grown :)) beef now and then!

  42. Dr Benway says:

    Dr. Lipson:

    The issue, though, is not the relative merits of these diets, but whether the data support extravagant claims about them.

    And why is obvious point not obvious?

    Because of subtle linguistic equivocatons made possible by the network of associative links within our heads. “Restrictive” can be used in a mathematical sense as in referring to a subset of a larger set. The word also comes with a certain emotional valence as in, “you are restricted to your room, young man.”

    And thus Rob’s wounded feelings when I said his baby’s face was kinda funny looking paired the word “vegan” with “restrictive.”

    I went to a talk by Dean Ornish. Half of it –I kid you not– was an overview of marketing tricks. People don’t like being told “no.” So here’s how you can make them feel that their choices have actually been expanded…

    I’ve nothing against cro-magnon herding techniques per se. I just do not want them in my science.

    My point –and I do have one– ist that we can’t settle on “the point” of our discussion if we’re not defining words in the same manner.

  43. Dr Benway says:

    Strike through tag fail. *sigh*

  44. Joe says:

    Dackson 19 Oct 2009 at 9:35 am “Joe,
    Yes, but I think you then have the situation that Rob was setting up – taking away the protein from a meal without replacing it with another source.”

    I don’t quite get that. You know the problem so you compensate by having a heaping helping of musical beans. My sis-in-law is quite smart and read the literature on nutrition and lives well.

    Dackson 19 Oct 2009 at 9:41 am “Joe,
    Besides, I love a piece of (pasture raised, grass-fed, locally grown :) ) beef now and then!”

    I don’t quite get that either. I thought you were pining to return to your vegetarian ways.

  45. Rob Tarzwell says:

    Whoa! Much feedback, and I like the ongoing vigorous discussion.

    Dr. Benway, I sincerely hope you don’t talk to patients the way you speak with discussants on this board. Clearly, you find yourself hilarious. That surely means it must be so.

    To all others interested in sincere engagement with the issues: I agree that, in strict terms, a vegan diet allows for fewer total items in the food universe than the ADA diet. My point is a cultural one, not a mathematical one.

    In my experience working with patients around dietary issues, the vegan crew, while assiduously avoiding meat and dairy, actually manage to incorporate a far wider variety of menu items. I’ll readily admit this is limited, anecdotal experience, and it is thus not at the level I’d offer at a conference, but it does strike me as interesting.

    My standard diet patients typically manage a limited rotation of greens (spinach, broccoli, romaine salad, green beans, snap peas), starch (potatoes, noodles, rice), and meat (beef, pork, chicken).

    My vegan patients are off the chart with their realized choices and with their ways of conceiving of choices. A protein might also be a fibre, and it might also be in the salad, for instance chick peas. The salad might be the main dish. Most of the fat might come from nuts and avocados. Tofu might be the main, or it might be the dessert. Yada, yada.

    I’m not saying this is better. It simply strikes me as different, in a qualitative way. There’s probably a self-selection bias going on here. It’s typically not easy or straightforward to choose a vegan diet. It is often motivated by ethical reasons and perceived health benefits. So, that crowd is more engaged with food choices and general consciousness about the impact of their food choices on themselves, the environment, and animal welfare.

    However, it also strikes me as interesting that this ostensibly tougher diet was found by Barnard et al to be easier to stick to, along with having small but significant benefits over the ADA diet. Presumably, those randomzied to a plant-based diet were not vegans beforehand. Thus, something about that diet was simply easier from an adherence standpoint. Given that we can’t even get half of glaucoma patients to stick with their eye drops, adherence boosting measures seem like a rather worthwhile goal in a disease as devastating as diabetes.

    That said, there certainly may be the possibility of allegiance bias at play. Dr. Barnard makes no secret of his preference for a plant-based diet. So, were his raters independent of that allegiance, or were they blinded to the dietary arms of the participants? Crucial questions, and I hope he comes back to the thread to answer them.

  46. Dr Benway says:

    So, that crowd is more engaged with food choices and general consciousness about the impact of their food choices on themselves, the environment, and animal welfare.

    So maybe the prescribed diet isn’t the variable that matters. Maybe being awesome is really good for your diabetes.

  47. Dr Benway says:

    Dr. Benway, I sincerely hope you don’t talk to patients the way you speak with discussants on this board.

    Ahem. And who threw the first “hopelessly unsophisticated lunch-lady” meme?

    Your politics may be correct. But it has no place in my science, which doesnt’ give a fig for what is awesome but only for what is true.

    There was a time when doctors would rather shoot themselves in the head than be perceived as salesmen.

  48. Scott says:

    There’s probably a self-selection bias going on here.

    Emphasis added. That’s actually a very weak conclusion. It would be more accurate to say that there is a self-selection bias (the points you mentioned following the bit I quoted are more than adequate to reach this conclusion), of undetermined size, but with the potential to account for all of the observed difference.

  49. the bug guy says:

    Considering that Veganism is more than just a diet plan, I’d say that there was a good chance that there was self-selection going on and that the participants in that arm had considerably more motivation to follow the diet.

  50. Mark Crislip says:

    The “I hope you don’t talk that way with your patients” line drives. me. nuts.

    Well, duh. I talk to my patients differently than my colleagues and differently when I am in the pub having a beer and differently when I am with my grand parents and differently when am I with my wife and differently than when I am with my kids and differently etc etc etc.

    You always change the tone and content depending on the social/professional situation.

    Such a comment is so, so, so… arrrgghhhhhhhhhhhhhhhhhh.
    Thud.

  51. Rob Tarzwell says:

    Scott and bug guy, veganism as a personal choice is different from random assignment, as per the Barnard study. It is these randomly assigned individuals who had easier compliance, assuming we can account for investigator allegiance.

    Hard to see what’s being sold there. The datum is either true or it is false. Not sure what politics has to do with it, or waterboards, or lunch-ladies, or “arrrgghhhhhhhhh.”

    The main responses so far to this datum being pointed out are multiple ad hominem attacks against the guy who points it out, a conflation of veganism as a self-choice vs random assignment, and the unsubstantiated assertion that trial subjects self-selected.

    Is this really the best that Science Based Medicine has to offer by way of informed critique?

  52. Dr Benway says:

    Rob, I agree: “self selected” doesn’t fit with random assignment and so can’t account for “easier compliance.”

    Why is it important to consider other factors that might account for the easier compliance? Because it’s not obvious why a vegan diet should be easier for patients to follow than an ADA diet.

    Hard to see what’s being sold there. The datum is either true or it is false. Not sure what politics has to do with it, or waterboards, or lunch-ladies, or “arrrgghhhhhhhhh.”

    I’ll try my best to explain:

    1. You have been trying to sell veganism. Nothing wrong with that all by itself. The crime arises when one over-states the data or its implications –in this case, regarding diabetes control as measured by HgA1c. We are frowning at Barnard for that.

    2. Politics = desire. Science = truth. Truth should never take a backseat to desire.

    3. The “waterboard” was my metaphor for prior probability (see Bayes’ Theorem). Data are not useful when the prior probability of a hypothesis under study is low.

    4. The “lunch lady” is the person who doesn’t know what a legume is or what a vegan diet is like.

    5. The “arrrgghhhhhhhhh” is the sound of a traumatic brain injury due to head slamming abruptly against desk.

    The main responses so far to this datum being pointed out are multiple ad hominem attacks against the guy who points it out, a conflation of veganism as a self-choice vs random assignment, and the unsubstantiated assertion that trial subjects self-selected.

    Subjects can’t be both self-selected and randomly assigned. You do have a point there. Scott and the bug guy either didn’t read the article above closely, or they forgot the details after reading all the comments, or they are retarded. Note that “retarded” in this context is not an ad hominem.

    Is this really the best that Science Based Medicine has to offer by way of informed critique?

    The critique has been made and it stands: There’s no reason to prefer a vegan diet over an ADA diet in terms of glucose control in diabetes. There may be other reasons to prefer a vegan diet, but discussion of those reasons in this context may cause some people to miss the point about glucose control.

  53. Rob Tarzwell says:

    Ok, now you’re talking, and your points make sense to me. Let me clarify that I’m not trying to sell veganism, just trying to make sure it gets a fair hearing. A plant-based diet can be consistent with well-controlled diabetes. Dr. Barnard will have to speak for his own further claims of superiority.

    I think a prima facie case can be made that the prior probability of a vegan diet being easier to maintain than an ADA diet is paradoxical. A very testable null hypothesis follows from that:

    H0: The vegan diet is not easier to adhere to than the ADA diet.

    It’s not straightforward to me how one would go about assigning antecedent probability to such an hypothesis, but probability bands could be assigned broadly. The antecedent probability that clocks tick slower in translating reference frames used to be very low too.

    We can’t conclude from Barnard’s study that veganism is easier to maintain than ADA diet, but we have a signal, enough of a signal to legitimately warrant investigation into adherence. I’m not sure how that study would be designed, but it would have to at least include blinded raters with quality auditing of rating sessions to ensure raters aren’t accidentally or intentionally becoming unblinded.

    If such a study were adequately powered such that the null hypothesis could be confidently refuted, then legitimate reasons, from a strict glucose-control point of view, for preferring the paradoxically more restrictive diet, would obtain, antecedent probability notwithstanding.

  54. Dr Benway says:

    If we can objectively measure HgA1c, lipid profile, and weight, why do we care about compliance which is fraught with all the problems of human memory?

  55. the bug guy says:

    Dr. Benway is correct, I had forgotten about the random assignment in the original report.

    I’m still concerned about Dr. Barnard’s claim:

    The reason people adapt well to what one might imagine to be a restrictive diet seems to be that (1) they can eat as much as they want without calorie limits, (2) they do not have to restrict carbohydrate, (3) their tastes change, rather like an ex-smoker who no longer cares for cigarettes, (4) they like the benefits (weight loss, etc.), and (5) the diet really doesn’t feel so restrictive when people realize the range of foods it includes.

    This sounds more like a sales pitch for a fad diet. Eating as much as you want without calorie limits and losing weight are not believable combinations. With such a basic dissonance, I have trouble taking much else at face value.

    As for my comments about Veganism, perhaps the problem is that Dr. Barnard is using the word differently than I understand and perhaps he should simply be using the term ‘vegetarian’ instead to separate it from the Vegan lifestyle.

    From comments above describing the diet choices of ADA versus the vegetarian diet, I have to wonder if the difference may be what the participants in the different arms were taught about their options. The ADA diet is just as varied as a Vegan diet, except having all the animal product options in addition. The simple reality is that the Vegan diet has fewer options and the only way to say otherwise if for those on the ADA diet not to be given the same level of education on their options.

  56. the bug guy says:

    With long threads spread over time, you can lose track of details. It’s a hazard of the discussion format.

    Rob Tarzwell brought up the idea of self selection, ethics and compliance, to which I responded.

    I’m not saying this is better. It simply strikes me as different, in a qualitative way. There’s probably a self-selection bias going on here. It’s typically not easy or straightforward to choose a vegan diet. It is often motivated by ethical reasons and perceived health benefits. So, that crowd is more engaged with food choices and general consciousness about the impact of their food choices on themselves, the environment, and animal welfare.

  57. the bug guy says:

    I realized my last post may be confusing in that it looks like the blockquote was of my response to Rob Tarzwell. The blockquote is from an upthread post by Rob Tarzwell andi it was to that comment that I made mine about self-selection.

  58. Fifi says:

    This is just silly. Vegan diets are more difficult to maintain for anyone – particularly if one isn’t relying to heavily upon highly processed fake “meat” and “cheese” – just ask most Vegans. Even a vegetarian diet can be difficult to maintain in social situations – though these days it’s much easier to find vegetarian options and more people cater to vegetarians as well (and, no, fish is not a vegetable and, yes, the fact that soup is made with chicken broth means it’s not just vegetable soup).

    I’ve never been vegan but I have quite a few vegan friends who I cook for and was vegetarian for a long time. It’s more work, even with a vegetarian diet, to make sure you’re getting proper nutrition (especially for women). Of course, it also requires knowledge and planning to get proper nutrition from an omnivorous diet too.

    The one area where putting someone on a vegan diet may be useful is that it changes the way someone thinks about eating and teaches new cooking and eating habits. For instance, how much of a sweet tooth one has is partially influenced by how much sugar one consumes so any diet that restricts sugar may have an influence on lowering one’s desire for sugar – which would obviously be a good thing if you’re diabetic. (Americans seem to like even savory dishes to be disgustingly sweet a lot of the time and most processed foods seem to have some form of sugar in them.) Of course, a healthy omnivorous diet is just as healthy. Any diet can be unhealthy – even a vegan or vegetarian one – and any diet that is well considered and thought out can be healthy. If someone is switching from an unhealthy diet to a healthy one, it’s going to take effort and changing eating habits no matter whether it’s vegan or omnivorous. How compliant every participant is would also have to do with individual participants and whether making a big or a small change is more sustainable for them (and people do differ in this area).

  59. Scott says:

    My comment was more limited in scope than it was taken as – I was referring only to Rob’s patients (where he himself agreed that there was a probable selection effect; the point of my post was that it’s more than probable in that context), not to the original study.

  60. Rob Tarzwell says:

    @Fifi, I think your third paragraph explains rather elegantly what I was fumbling toward. Mindfulness is possibly the confounding variable, but that’s just an hypothesis.

    @Dr. Benway, measuring lab values is lovely. Lovelier still is finding a way to help patients achieve and maintain normal lab values. I’m not talking about measuring compliance. I’m talking about achieving compliance. A “Check Engine” light is pretty useless when I’m in the desert.

    @the bug guy, if I may speak on behalf of Dr. Barnard, when he talks about eating whatever you want but not gaining weight on a vegan diet, I believe he means that *satiety* is achieved on a plant-based diet without consuming excessive caloric intake.

  61. Dr Benway says:

    I’m not talking about measuring compliance. I’m talking about achieving compliance.

    And how do you measure “achieving compliance”?

  62. Rob Tarzwell says:

    Well, I’ll admit I can’t speak directly to that point, but as there is a rather large literature on compliance, with widely accepted results, across numerous treatment modalities for a broad range of conditions, I imagine previously worked out methodologies could be employed successfully.

    Were you serious, by the way?

  63. Dr Benway says:

    Why do we care about dietary compliance? Because, with respect to diabetes, we imagine that better compliance will mean better glucose control.

    So let’s measure the HgA1c and forget “compliance.”

    When you throw enough variables into your statistics software, by chance alone something will have a significant p-value. “Compliance” might be one of those.

  64. Rob Tarzwell says:

    But measuring A1C only tells us if subjects or patients have been more-or-less compliant over the previous 3 months. It in no way encourages or improves compliance.

    What I’m saying is, *if* the signal from Barnard’s study is valid, then it is scientifically worthwhile to directly measure whether a plant-based diet is easier to comply with than an ADA diet.

    It’s a clear, testable hypothesis. I don’t see the point of bringing A1C into it.

  65. Dr Benway says:

    It’s a clear, testable hypothesis. I don’t see the point of bringing A1C into it.

    If the HgA1c, lipids, and weight in a diabetic are normal, the patient is being sufficiently compliant with the recommended diet.

    I may not see the wind. But if the leaves are rustling, I can tell how strong it’s blowing and in which direction.

  66. Dr Benway says:

    Rob, I’m still waiting for your proposed method of measuring compliance, knowing that dietary self-report is notoriously unreliable.

  67. Rob Tarzwell says:

    Of course self-report is problematic, but relying on proxy-markers to make firm conclusions about the primary end-point is also problematic. I don’t care if your systolic bp goes down ten points. I care who gets a stroke or heart-attack.

    If you’re offering me $150,000 to conduct the study, I’ll be more than happy to write a detailed proposal for monitoring compliance. In brief, use methods which encourage honesty and which minimize the need for detailed recall:

    1) Daily check-in by the research team to take a daily food diary
    2) Frequent reminders that the goal of the study is to see if the diet is easy to stick to, and therefore we definitely encourage and want to know if there have been slips.
    3) Qualitative semi-structured interviews which ask questions like: what do you like/dislike about this diet? Do you enjoy it? What is hard/easy about this diet?
    4) Deployment of validated instruments, e.g. http://journals.cambridge.org/download.php?file=%2FPHN%2FPHN12_04%2FS1368980008002310a.pdf&code=fd3de6bcaaee43a3a69d566e33aeaf5e

    Etc, etc. To be sure, there are problems with this type of research, but I’m not going to throw up my hands, and most importantly, what I’ve just described is *not* the final word in good field-based compliance research methodology. It’s just me thinking about it and comparing it with work I’ve done in assessing outcomes in psychotherapy using semi-quantitative measures and semi-structured qualitative interviews.

  68. Rob Tarzwell says:

    And on top of that, if the primary hypothesis is being well pursued directly, then, yes, there’s certainly a role for proxy markers as validators.

  69. Dr Benway says:

    Ok so you measure the HgA1c and you have some forms or interviews to give you a compliance score. Possible observations:

    1. HgA1c good, compliance good
    2. HgA1c good, compliance bad
    3. HgA1c bad, compliance good
    4. HgA1c bad, compliance bad

    It’s easy to understand #1 and #4. But what should we think about #2 and #3?

    Which do you believe when they contradict each other?

    When the I&Os say the patient isn’t eating or drinking but the weights are stable, which measure is more likely to be true?

  70. Peter Lipson says:

    I gotta say that IRL, that’s a valid approach. No matter what a patient reports about lifestyle changes, if the BMI is rising, they are doing something wrong. If the A1C is rising, they are doing something wrong.

  71. Dr Benway says:

    When HgbA1c and compliance contradict, we can either:

    1. trust compliance over HgbA1c
    2. trust HgbA1c over compliance.

    Of course we’ll trust an objective measure directly relevant to diabetes rather than a subjective measure only indirectly relevant to diabetes.

    Dr. Barnard’s vegan patients were reportedly more compliant with their diets than the ADA patients. However both groups had similar HgbA1c measures. From this I conclude that Dr. Barnard’s vegan patients were sucking up to the famous animal rights vegan guru a little more than the ADAs.

  72. Rob Tarzwell says:

    Dr. Benway, yes, there may have been some research-subject compliance, or investigator allegiance bias.

    It’s possible I’m simply being unclear, or I’m misunderstanding your point.

    It seems that both diets produce acceptable results. One may be easier to stick to. If so, that’s worth knowing, because if that’s a long-term result, then that is a point in favour of plant-based diet.

    I agree that, *clinically*, I’m far more apt to trust the A1C than the dietary report. But *scientifically*, if I want to answer the question, “Is a plant-based diet easier to stick to than an ADA diet?” I simply have to do the science the right way, which involves actually monitoring what gets eaten.

  73. Dr Benway says:

    Rob, the point I’m making is this: the map is not the territory. Don’t let words fool you. A rose by any other name…

    “Compliance” may sound like something real. I think I understand what it means; you think you understand what it means. But whatever goes on in our heads when we contemplate “compliance” is beside the point from a scientific point of view.

    Science sees the world from the position of a generic anyman with no particular language or cultural context. Generic Science Man is a simple soul who must see it to believe it. If you can’t take a photo of it, he probably can’t see it. Can you photograph “compliance”? Not really, no. So for the sake of science, you must translate “compliance” into something Science Man can see, such as the HgbA1c.

    You have in mind some other way to represent the abstract concept “compliance” in concrete form, such as perhaps a score on a form completed during a structured interview. OK, fine. But I doubt that such a measure will prove a more valid or reliable representation of dietary compliance than the HgbA1c.

  74. Rob Tarzwell says:

    Maybe not, but it will be an attempt to directly measure the construct in question, one I certainly agree has all the potential in the world to be slippery and perilous.

    To use a semi-related example, though, I think there has been some genuinely good psychiatric epidemiology done in this world, all done without lab work, based on interviews, relying on ever-shifting, highly contested constructs.

    Despite all that, the psychiatric epidemiologists have provided us with reasonably firm data about the true burden and reasonably precise nature of mental suffering in the world.

    I’d even go so far as to argue that they were doing science. All without a lab value in sight.

  75. Dr Benway says:

    I feel you pain, Rob. Once upon a time I wanted to do research in psychoanalysis. If you think “compliance” needs defending, imagine the headache of “projective identification.”

    I favor a broad definition of science involving four tests: corroboration, falsification, logic, parsimony. This definition doesn’t require any worship of numbers or a dogmatic belief in the randomized placebo-controlled trial as a “gold standard.”

    Often we do need to translate words into numbers to rule-out competing explanations involving miscommunication. And often we do need placebo controls to rule-out competing explanations involving expectational bias. But we might dream up some new way to serve these same purposes.

    There’s nothing in the above definition that limits science to particular fields of study. Messy domains riddled with subjective variables aren’t necessarily off limits. If terms can be defined with good inter-rater reliability, independent corroboration becomes possible and so science becomes possible.

    The subjectivity of the compliance variable in the Barnard study isn’t actually the problem. Rather, its the redundancy of this variable with the HgbA1c as a measure of diabetes control.

    The parsimony rule requires us to ditch redundant variables. And the corroboration rule causes us to favor reliable measures over less reliable measures.

  76. Rob Tarzwell says:

    Dr. Benway, I think our thread may have reached its conclusion. I hope this is not the last clash/meeting of minds. If we ever meet in person at a conference, the first beer is on me.

    I simultaneously concede all your points and yet insist that the best way to measure a construct is directly, even if that construct is fuzzy at the edges. I grow increasingly suspicious of proxy markers with the passage of time, even if they are hard-edged.

    Speaking of psychoanalytic research, I think my favourite attempt to investigate reaction formation is a 1996 paper from the Journal of Abnormal Psychology. This may be the closest we’ve ever come to empirical demonstration of a defense mechanism.

    http://psycnet.apa.org/psycinfo/1996-00463-014

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