How to Design a Misleading Study to Show Diet Doesn’t Work

Image Credit: Yoshihide Nomura / Flickr. This image has been modified.

How to Design a Misleading Study to Show Diet Doesn’t Work

A study out of the University of North Carolina found no association between dietary fiber intake and diverticulosis. They compared those who ate the highest amount of fiber, 25 grams, to those who ate the smallest amount, which was three times lower at only 8 grams. Finding no difference in disease rates, researchers concluded that a low-fiber diet was not associated with diverticulosis.

The university sent out a press release entitled: “Diets high in fiber won’t protect against diverticulosis.” The media picked it up and ran headlines such as “High-fiber diet may not protect against diverticulosis, study finds.” It went all over the paleo blogs and even medical journals, publishing such statements as an “important and provocative paper…calls into question” the fiber theory of the development of diverticulosis. Other editorials, though, caught the study’s critical flaw. To understand this, let’s turn to another dietary deficiency disease: scurvy.

Medical experiments on prisoners at Iowa State Penitentiary showed that clinical signs of scurvy start appearing after just 29 days without vitamin C. Experiments on pacifists during World War II showed that it takes about 10 mg of vitamin C a day to prevent scurvy. Imagine going back a few centuries when they were still trying to figure scurvy out. Dr. James Linde had this radical theory that citrus fruits could cure scurvy. What if an experiment was designed to test this crazy theory, in which sailors were given the juice of either one wedge of lemon or three wedges of lemon each day? If a month later on the high seas there was no difference in scurvy rates, one might see headlines from printing presses touting that a low-vitamin C diet is not associated with scurvy.

Well, a wedge of lemon only yields about 2 mg of vitamin C, and it takes 10 mg to prevent scurvy. They would have been comparing one vitamin C-deficient dose to another vitamin C-deficient dose. No wonder there would be no difference in scurvy rates. We evolved eating so many plants that we likely averaged around 600 mg of vitamin C a day. That’s what our bodies are biologically used to getting.

What about fiber? How much fiber are we used to getting? More than 100 grams a day! The highest fiber intake group in the North Carolina study was only eating 25 grams, which is less than the minimum recommended daily allowance of about 32 grams. The subjects didn’t even make the minimum! The study compared one fiber-deficient diet to another fiber-deficient diet—no wonder there was no difference in diverticulosis rates.

The African populations with essentially no diverticulosis ate diets consisting in part of very large platefuls of leafy vegetables—similar, perhaps, to what we were eating a few million years ago. They were eating plant-based diets containing 70 to 90 grams of fiber a day. Most vegetarians don’t even eat that many whole plant foods, although some do. At least vegetarians tend to hit the minimum mark, and they have less diverticulosis to show for it. A study of 47,000 people confirmed that “[c]onsuming a vegetarian diet and a high intake of dietary fiber were both associated with a lower risk of admission to hospital or death from diverticular disease.” They had enough people to tease it out. As you’ll see in my video Does Fiber Really Prevent Diverticulosis?, compared to people eating a single serving of meat a day or more, those who ate less than half a serving appeared to have a 16% lower risk and pescatarians (eating no meat except fish) had a risk down around 23%. Both of these results weren’t in and of themselves statistically significant, but eating vegetarian was. Vegetarians had 35% lower risk, and those eating strictly plant-based appeared to be at 78% lower risk.

As with all lifestyle interventions, it only works if you do it. High-fiber diets only work if they’re actually high in fiber.

There’s more great information in my video Diverticulosis: When Our Most Common Gut Disorder Hardly Existed.

This reminds me of an ancient video I did: Flawed Study Interpretation.

People commonly ask Do Vegetarians Get Enough Protein?, but maybe they should be more concerned where everyone else is getting their fiber. Ninety-seven percent of Americans don’t even reach the recommended daily minimum.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

104 responses to “How to Design a Misleading Study to Show Diet Doesn’t Work

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  1. This is off topic, but just wanted to mention that T. Colin Campbell will be lecturing at a fairly large venue outside Philadelphia. The advertisement went out about 2 weeks ago, and as of last week it was completely ‘sold out.’ (I say ‘sold out’ because it’s free:-)

      1. Google T Colin Campbell… too much info to post here! He is an amazing whole food plant based researcher. Have you watched the documentary “Food Matters”?

    1. Joan said.. “Misleading studies are linkbait, sometimes…”
      That is so true.. Big tobacco and big Pharma do this all the time.. I had to laugh when I just read that big Pharma has now proven that inflammation causes heart disease and cancer…
      AND they just came out with a drug that lowers said inflammation…..

      So they found a way to synthesize eating a WFPB diets…….. God knows what the side effects are… And how many millions they are gonna make…

        1. Doesn’t have to be a soup. They are delicious if you just cook them down to a mush. Meat eaters used to eat them with gammon but they are lovely as a side dish to grilled aubergine. or an avocado salad or even a Japanese style daikon pickle if you don’t want to cook aubergines in oil.

          1. With added cumin coriander and some sweet spices (garam masala), you have Indian dal. Throw in lotsa roasted garlic and call it tarka dal.

  2. I’ve often thought that for the most part, studies waste the potential for valuable information.

    That is, they are narrowly focused on one thing and stop when they’ve determined the outcome for that one thing.

    But what if they went further… that is, using the same participants and then add something else to the diet or treatment etc. to see what outcome the “something else” would provide.

    By doing this we would increase our knowledge greatly and get more bang for the buck for each and every study done.

  3. That is so interesting. When I read the 25 grams for the high group I first thought that was still rather low but just breezed past it. It didn’t occur to me that they were really just comparing two low volume groups and coming up with the misleading result until you pointed this out.

    1. Lee
      One tablespoon of flax has ten grams of fiber , most people would be able to use two a day .Hint measure flax whole , then grind and stir into water or smoothie or however you take flax . Ground flax bulks up so if you measure it ground you only get 7 grams of fiber per tablespoon.

      1. Right Ignatius, there are a number of foods that are really high in fiber that help boost the daily average when eaten regularly. Beans, lentils, artichoke hearts, manna bread, flax, chia etc. Getting 5 gm of fiber average per 100 cal is not difficult, so for a woman eating 1500 cal per day, 75 gm of fiber is reasonable. Getting 100 gm of fiber would not be difficult for someone eating more (say a swimmer, runner or cyclist for example) or for someone focuses on the higher fiber foods.

      2. Dr Gregor posted in a video before that we should consume “2” heaping T full per day of Organic Ground Flax. He said it also can reverse heart disease. I have it everyday in my overnight oats.

        1. It can HELP reverse heart disease. Nothing magically takes away atherosclerosis by itself, and I see claims omitting that important word ‘helps’ more and more. FDA, you seem more overwhelmed all the time.

  4. As a research scientist, bad papers are one of my biggest pet peeves. Especially when they come from highly respected labs, because no one calls them out on it. (My other pet peeves are bad science reporting by journalists, and labs who spend more time and money on PR than actual research…) Scientists are people, too, prone to mistakes and bias despite the best of intentions. I’m just really surprised when glaring errors like this slip past peer review. But, then again, peers are just other scientists chosen by the journal to review the work, and journals are not immune from bias, nepotism, and corruption. Every scientific paper should be read with a healthy dose of skepticism.

  5. Why believe this blog?

    1 diverticulosis can have several causes. This blog assumes there is only one, fiber. Example. It could be probiotics, genetics, inmune system, even low salt, etc.

    2 there is no direct relation between diverticulosis and fiber intake when other factors are omitted. This blog assumes other factors do not matter.

    3 Many populations with low fiber diets don’t suffer from diverticulosis. This blog omits this.

    1. Why believe this blog? Because Dr. G presents peer-reviewed published research throughout this website in support of his statements. If you can’t cite peer-reviewed published research in support of your comments….which you don’t….then you come across as a troll and everyone will simply laugh at you like you’re trying to convince us the earth is flat.

      Dr. Ben

            1. Panchito, you might want to actually read the studies you cite. They do not support your argument. They support Dr. Greger. Your first citation is the low fiber study that Dr. G’s blog references. They used 25 grams max as their “high fiber” group. Re-read Dr. G’s blog to see why that’s a problem.
              Your second citation reviews the available evidence, showing many studies demonstrating a solid link between high fiber intake and low risk of diverticulosis.

              Dr. Ben

      1. Also, remember that this paper came out of the U of North Carolina. A state known for having more animal waste than human waste. That should tell you something about how important the meat industry is to them.

    2. You also get genetic self selection so that the survivors on any given diet over time are those best adapted to it. None of it will necessarily replicate for anyone else from a different genetic heritage. It is like asians and arsenic in rice…… Of course today, genetic self selection does not work as it used to as we intervene to enable people with all sorts of maladaptations to survive and breed….. It might just be that trawling the planet for evidence of ancient peoples and their diets as evidence of good foods for a long life is a folly.

      1. Panchito, you might want to actually read the studies you cite. And they are very important because they support Dr. Greger. Your first citation is the low fiber study that Dr. G’s blog references. They used 25 grams max as their “high fiber” group. Re-read Dr. G’s blog to see why that’s a problem.
        Your second citation reviews the available evidence, showing many studies demonstrating a solid link between high fiber intake and low risk of diverticulosis. Are there secondary co-factors? Probably, but the primary cause is low fiber intake….25 grams is low fiber intake.

        Dr. Ben

      2. Thanks for the link. I think we need to look at Diverticulitis from a more scientific angle. OK, it is observed that populations of the world that eat a lot of fiber, have less chance for Diverticulitis. But association does not mean causation. Just like if we say people in countries with smart phone (because they are affluent) has more cancer than people without (because they are poor) and then conclude that smartphone causes cancer, which is not true.

        So my guess and this is only a guess, Diverticulitis is caused by bacteria and infection and inflammation inside the intestine. So when you eat a lot of fruits and vegetables, you create more beneficial bacteria and less inflammation, which fix the Diverticulitis problem. Case in point is that Japanese eat very little fiber since they are in an island country with little farm land, and yet Japanese do not have a lot of diseases in general. That’s because Japanese eat a lot of other foods, in particular fermented foods and foods rich in Omega 3, which create good bacteria probiotics and reduce inflammation.

        So the UNC research is not totally wrong but the results are misinterpreted.

        ” Although data are far from conclusive, there is some evidence to suggest that diverticulosis may be associated with chronic abdominal symptoms, with or without underlying chronic inflammatory changes in the involved segment of the colon.”

        1. You’re confusing diverticulosis with diverticulitis. The published studies already review and analyze the science well as summarized by Dr. G. High fiber prevents diverticulosis. You can’t get diverticulitis unless you already have diverticulosis.

          Dr. Ben


      3. Diverticulosis and Diverticulitis.

        “Risk factors for the development of diverticulitis include obesity, smoking, nonsteroidal anti-inflammatory drugs, corticosteroids, and opiates. In contrast, fiber may be protective, but recent studies have questioned the role of fiber in developing diverticular disease. “

        1. Don’t confuse risk factors with the overwhelming evidence presented in your citation that low fiber is the primary cause, and don’t confuse the opinion of the author with facts. Risk factors do just that: they increase the risk.

          The author cites many studies demonstrating the unequivocal relationship between low fiber and diverticulosis, and then makes his statement about “recent studies call into question….” Anyone is welcome to call anything “into question,” even when they are based on poorly designed studies like the one Dr. G cites.

          If you’d like to make an argument that is compelling, you’ll need real objective evidence, not conjecture that contradicts all available evidence.
          That’s the fodder of tinfoil hat conspiracy theorists…and those that have a vested interest in the sale of processed carbs and animal products.

          Dr. Ben


    3. Exactly. Just for the sake of argument, if one eats fiber pill, or non nutritious or non digestible fiber such as chewing on cardboard, will it eliminate diverticulitis? Probably not. Why? It’s because it’s not the fiber but it’s the phytonutrients in plant foods that reduce inflammation and which create the probiotics.

      So it’s very possible to eat little fiber but eat a lot of fermented foods and reduce the risk of diverticulitis.

      That is probably what the UNC research tried to say but it was twisted around.

    4. Can you please cite data on the link between low salt and diverticulitis?

      I am guessing you’re new to Dr. Greger’s attempts to support his statements are extensive. You can click to open the transcript to click through to the research.

  6. I would be very curious to know if there has ever been a study to break out the contribution of squatting when having a bowel movement on level ground as opposed to sitting on the toilet as we do to the very low diverticulosis rates in Africa?

    In my own life fibre is very important, but I also had to learn how avoid using pressure when sitting (deep diaphragmatic breathing and the ‘touching the floor’ technique suggested by Dr. Greger in a recent video). As a survivor of 40 years of type two diabetes I have had to adjust to problems like this, since I have constipation pretty much no matter how much fibre I eat.

    Dr. Greger: Did you know that Microsoft does not have your name in their spell check program?

    1. Not in my clinical experience Jerry. Do you have any published evidence to support your claim “most health conscious meat eaters eat tons of fruits and vegetables”?

      What objective evidence is there that essential nutrients are missing from PF?

      Dr. Ben

      1. I posted plenty of evidences throughout my posts. If you guys care about reading them rather than trashing then you will see where my reasoning came from.

        1. Compelling evidence has several requirements, two of which are: 1) it needs to be peer-reviewed and published in reputable journals, and 2) it needs to support your contention. What you call “evidence” doesn’t qualify.

          Dr. Ben

        2. Ok, Jerry dairy or Panchito Nando’s or whatever you call yourselves, go on post plenty more ‘evidence’…..just to make me laugh that is. Not that I ever look at them though…

      2. B12. See Dr. G’s videos. Elevated homocysteine probably due to a deficiency in B12. Although I love the work on this site about the benefits of whole foods there is definitely a vegan bias and anyone who suggests anything to the contrary is regarded as a troll. Even from the mature moderator.
        This is where credibility is diminished. For the record my diet is around 90% plant based

        1. This site is vegan biased because the overwhelming peer-reviewed published clinical evidence clearly points to the fact that all available animal products increase death and disease. Dr. G and all the moderators on this site have no bias whatsoever, except for optimum health.

          The only people we treat as trolls are the posters who spout their non-vegan agenda that has no basis in fact at all. We would all be very interested in unbiased peer-reviewed published research in support of any animal products as being healthier than a WFPB lifestyle. It simply does not exist.

          Dr. Ben

          1. I think the problem with the USA is that the food available to the people and the large corporations influence is so disgustingly bad that no wonder there is such a push back against anything animal or synthetic. Just eat real food.
            No comment on B12?

            1. For millions of years humans thought the earth was flat. Only real evidence proved this is not correct. Our senses often deceive which is why we do peer-reviewed objective research. Your notions about animal products are refuted by all objective evidence we are aware of. We’d all be happy to consider your hypothesis if you have some evidence in support of your contentions. Absent that, all available evidence suggests that you put yourself at risk for being sicker and dying earlier than you would if you at a plant based diet. Certainly your choice.

              B12? It’s created by bacteria, not animals. Apes eat feces, bugs and dirt as their B12 source which I have a cultural aversion to, so I take 15 ug/day of methylcobalamin/adenosylcobalamin.

              Dr. Ben

              1. Your views border on religious dogma. Look around the world at different countries with very long lived populations. I understand this can be difficult for some to accept but they do eat meat. Humans do not have the teeth of a herbivore or a carnivore. Look at the big picture of evolution. Omnivores tend to eat what is available. Chimpanzees also hunt other monkeys and other animals but also fruits , nuts etc. Many peer reviewed studies are so confounded which is why correlation not causation can only be concluded.
                “Sicker and dying earlier” . So by your logic most vegans should be living to 100 as humans are capable of achieving this. Can you demonstrate this?
                Elevated homocysteine is associated with CVD and vegans have “terrible” levels

                1. Scott, yes, I’m dogmatic when it comes to facts. Your statements make it obvious that you have not read the peer-reviewed published studies that overwhelmingly support the notion that a WFPB lifestyle is the lowest risk diet. The Okinawans, the Adventists, the Chinese, the rural Africans, all live very long lives on a WFPB. Please cite a single objective study in support of your contention that meat eaters live long healthy lives. There are none. Please don’t bring up Eskimos as the anecdotal reports about their supposed health and longevity were debunked long ago. Also, cave paintings of people killing animals don’t count either.

                  Chimpanzees? Better fact check. Their diets are well documented to be 98% plant based. Sure they hunt the occasional monkey but animal products are documented as less then 2% of their diet, and unless you’re eating monkey, it doesn’t apply to humans. Truly wild game contains minimal fat. You can’t buy anything like it.

                  Evolutionary adaption doesn’t count, otherwise elephants, cows and horses would be eating meat.

                  You’re welcome to throw the real science in the trash can as “confounded”
                  as Big Food and Big Pharma want you too. As Dr. G says, “doubt is their product” They know if they can confuse you a little, you’ll throw in the towel and continue to buy what they sell, just like Big Tobacco did for years. Your other choice is to learn to understand the statistics at which point you’ll see there is no doubt, which is why this site exists and why its garnering a larger and larger following as time goes on.

                  Vegans have terrible homocysteine levels? Again, not supported by any evidence.

                  Overall, you’ll need to provide peer-reviewed citations if you’re going to make assertions that contradicts the facts on this site or everyone will just laugh at you as just another meat addicted troll.

                  Dr. Ben

                  1. Re: The Okinawans, the Adventists, the Chinese, the rural Africans, all live very long lives on a WFPB.

                    LOL, Doc. Have you been to Japan or China or Africa? I don’t think that Japanese and Chinese eat only plant foods. In fact, they eat a lot of meat, seafoods and (saturated) fats. As for rural Africa, sure they don’t have a lot of diseases, but their longevity is very short. When people die young, cancer has not striken them yet. As for the Adventists, do you know that they live in a good community and they don’t smoke or drink and that contributes a lot to their longevity. Just remember that more than 95% of the world population is not vegan and a lot of people live a long and healthy life.

                  2. Typically you have resorted to juvenile attacks on anyone that presents a reasonable argument. Do you understand what confounded variables are?Confounding occurs when the experimental controls do not allow the experimenter to reasonably eliminate plausible alternative explanations for an observed relationship between independent and dependent variables.
                    You brought up the Eskimos
                    Lol RE: homocysteine. The video is on this site!!! Have you watched it? I have, many times.
                    I have no bias, so to refer to me as a meat addicted troll again reveals your bias and is immature and offensive. I have a feeling that if any study showed a natural omnivore diet with lots of fruit and vegetables nuts etc you would still not change your mind as it seems you also have another reason to be vegan.
                    Look at a mediterranean diet. Certainly a bias towards fruits and vegetables, legumes, nuts, olive oil.
                    Look at the Italian town of Acciaroli. They have very low rates of heart disease and Alzheimers and there are 300 centenarians out of 2000.American and Italian scientists have been investigating why. Is it the rosemary (high in anti oxidants) is it the walking, Is it the air etc. Or In my view a combination of all positive variables. They also eat fish.

                    1. Arguments? We don’t argue, we present peer reviewed published evidence on this site. I have yet to see you present a single peer-reviewed compelling citation to support your contentions.

                      Bringing up unsupplemented vegans has no relevance today with readily available B12. Your argument is uncompelling.

                      Statistical confounding? Very little out of the hundreds of studies presented on this site. If you think otherwise, we’d be happy to review the evidence if you post a number of citations that really invalidate the conclusion that WFPB results in optimal health.

                      “….scientist have been investigating why” is certainly not evidence. When the study publishes, we’d love to see it.

                      Interesting that you brought up the Mediterranean diet as it is truly whole food plant based.

                      You’re certainly welcome to follow your hopes and wishful thinking, but the rest of us are following the objective evidence.

                      Dr. Ben

                  3. Dr Ben, Thank you for your excellent comments throughout these discussions. Most of us readers of NutritionFacts appreciate your input. I have been a follower of this website since about 2013 and watched most of the videos from past years, too. I also follow several other websites such as those of Dr McDougall, Dr Joel Fuhrman, Dr T. Colin Campbell, etc. who also present unbiased evidence that humans have evolved to thrive on unprocessed plant foods. After changing to a WFPB diet, my health has improved tremendously. I think people have to just try it for themselves before they can understand the power of a whole plant food way of eating. Words will never convince some people. I look forward to your continued participation on the NutritionFacts website.

                    1. WFPB-Hal: Thank you for the feedback. I agree with you 100% and also read extensively from the sites you listed. Dr. McDougall’s presentations and newsletters are especially compelling and enlightening.

                      Dr. Ben

                2. Forced vegan evidence was found in my family.
                  I have lots of mail sent between family members during the 1840’s. Their letters reveal that they were rural farmers who had no access or could not afford meat. Some lived over 100 years old and most lived into their mid 90’s.

          2. Dr Ben, do you now admit that this site is a vegan site? Somebody else insisted that it is a (biased) nutritional site. Which one is true?

            1. I partially agree Jerry. This site is devoted to presenting the published peer-reviewed evidence for what to ingest for optimal health and longevity.
              There is no bias other than toward the unbiased evidence. The overwhelming evidence at this point is that a WFPB (unprocessed vegan) lifestyle is optimal. I have no doubt that if several studies were published showing the unequivocal benefits of adding wild deer meat to our diets that Dr. G would review it, and I would start eating it. I’d probably be clamoring to be first in line! At the moment, considering the number of people dying from CVD, stroke, cancer, diabetes, etc, the overwhelming evidence clearly points to the fact that animal products and refined carbs/fats are the cause. I wish it weren’t so.

              Dr. Ben

              1. I would concur with this statement as NF often produces data that shows which plant based foods are not healthy, like coconut oil for example, which many vegans were up in arms about being maligned. There is a subtle difference here as well. Veganism is a movement, while NF looks at whole foods, plant-based diets and says nothing about environment or ethics I would argue they are not a vegan site at all, though the word is being thrown around.

                This is about evidence based nutrition; not emotions, not culture, not business – something nutritional information seems to address more than facts > enter the ninja> Doc Greger who is Wu-Tanging this misinformation left and right.

                Do what you want with your own health, but WE have a problem with information that kills people like my dad, who are struggling with COPD, Diabetes and Heart Arrhythmia. With no doctors helping him do anything but take 10 pills at a cost of $200 a month, he could just eat fibrous plant food, which I had to tell him to do and is now actually saving him. Your rhetoric is not only selfish, but dangerous.

                1. Well said Marcello. We wish your dad well. 3 months ago I lost my father at 83 to lymphoma. He was the one that introduced me to this site years ago, but ascribed to a vegan lifestyle that included farm raised fish once per week along with processed carbs and aggressive, medication based, hypertension treatment. The few times that he “ate clean” and really followed a WFPB diet, he noticed that he felt much better. As you allude to, not following the evidence will likely lead to unfavorable outcomes.

                  Dr. Ben

                  1. Dear Dr. Ben,

                    I lost my father to lymphoma at age 80 also. I regret so much not knowing about plant-based diets although the information about them was known by Dr. Campbell and others. If my father, a chemist, had also known about them, he might never have gotten his lymphoma. My father’s doctors told him to eat meat and he took that advice.

                    Dr. Ben, thank you so much for your posts.


  7. Good information. However, I do not understand why this line needs to be included “—similar, perhaps, to what we were eating a few million years ago.” It is unnecessary and misleading. The Bible puts the world at 6150 plus or minus 50 years old . It would take another post to review the scientific literature for and again “millions of years.” One should not make the statement as if it were fact without such a review.

    1. Neal, if you want to quote the Bible, don’t forget that it says:

      “But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day.”

      The story about the earth’s age as described in the Bible never made any sense to me, even though I was brought up to believe it is literal and THE only thing to believe. I don’t believe that any more, and I don’t understand how people can ignore the above quote.

    2. I always laugh at statement that our ancestors eat this or that when they ate what was available where they lived. In reality, what we eat has a lot of influence from what our parents ate and our culture.

  8. I wonder if the researchers were so sensationalist in the paper.
    It would be interesting to see if it was just the university trying to create some publicity for themselves. “Look, our research found something!”

  9. Thanks, Dr. Greger, for this helpful analysis. Coincidentally, I ran into this article published today:

    The study recommends people to eat more fats as opposed to carbs. As a vegan, hearing this is a bit of concern since vegan diets do tend to have more carbs than fats for calories.

    It’d be great if you have a separate article reviewing it. I hope it’s one of those misleading studies.

    Thank you,

  10. Speaking of ‘”Misleading Studies”… tonight out of Toronto Canada the news had a study headlining “People need more fat and fewer carbs in their diet”. The study found that a high carb diet showed a 30% increase of dying (not sure of what) then those on a low carb diet. Also a moderate to high fat diet is ok. When you’re not eating much fat at all you show an increase chance of dying. In conclusion… fat is not the enemy if it goes too low they saw a worsening of heart disease.

    The study was not named but it was out of McMaster University in Toronto and one Dr. who spoke was Sonia Anand.

    If Dr. Gregor or the team could speak to this it would be very helpful. Thank you.

    1. You beat me to the punch on this one Lori and it is the PURE, or Prospective Urban Rural Epidemiology study they conducted that matches exactly with this blog post.

      First thing I noticed was the countries they looked at; Argentina, Bangladesh, Brazil, Canada, Chile, China, Colombia, India, Iran, Kazakhstan, Kyrgyzstan, Malaysia, Pakistan, Palestine, Philippines, Poland, Russia, Saudi Arabia, South Africa, Sudan, Sweden, Tanzania, Turkey, United Arab Emirates, Zimbabwe.

      If my memory serves correctly, none of the “Blue Zones” exist in any of the countries listed and when I think about cardiovascular disease I am going to bet countries like Argentina, Brazil and Canada are leading the pack, so this is exactly the way you design a bad study.

      The website for the study does not allow access to any of the protocol or follow-up but from this page it appears that the study will not actually be complete until 2030;
      “This study is currently recruiting participants.”

      Estimated Enrollment: 200000
      Actual Study Start Date: January 1, 2002
      Estimated Study Completion Date: December 31, 2030
      Estimated Primary Completion Date; December 31, 2030 (Final data collection date for primary outcome measure)

      I did find this about the group, led by the PURE Investigators-Writing Group;

      They mention; “The PURE study builds on the work and experience gained through conduct of the INTERHEART study”.

      Both studies were published by the Lancet.

      Trying to figure out who the PURE Investigators-Writing Group was and their funding I found this article referring to yet another study, the INTERSTROKE study, which in this article is being challenged, again the same group emerges in response saying the PURE study is looking at data now regarding social factors but it appears their MO is using fancy language to degrade popular recommendations.

      I also found this article as well, which revealed more information about their methodology than the PURE page itself, giving details as to how the PURE study is being conducted and it’s challenges;

      This is going to take a lot of unpacking but the funding is provided as such; “This work was carried out through funding by the Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Canada and with the aid of a grant from the International Development Research Centre, Ottawa, Canada. Information on the Centre is available on the web at”

      “We fund researchers driving global change” As a current human Nutrition student at the University of Manitoba, another university doing constant “damage control” against plant-based diets, I am once again ashamed as this is a Canadian led initiative funnelling money through a university. I think they need to be held accountable for this waste our of our tax payer dollars, they can be contacted here;

      “Transparency means openness. It allows Canadians to hold the government accountable through the proactive release of information on government activities, programs, policies, and services in formats that are easy to find, access, and use. Transparency is the key element in the Government of Canada’s Commitment to Open Government, which aims to increase access to data, information and dialogue.

      IDRC exercises transparency by providing information on its website, and in its publications, reports to Parliament and public outreach programs. In addition, as a research organization, IDRC also maintains transparency with the research community, and the general public, by making the results of its projects – studies, papers, articles, etc. available to all.”

      I would like access to the PURE study and have requested it, if they do not reply I will have to go through the IDRC, per the transparency statement above. Stay tuned.

      …this is a mountain I am not sure I can climb on my own, however, and I imagine it would take the entire Nutrition Facts team to tackle this abuse of study.

      1. Wow! That is some impressive sleuthing Sherlock. If you don’t work for Dr. Greger’s team, you sure have the skills.

        It shows how complicated and time consuming reviewing these studies can be. I have a new appreciation for this site. Thank you for going into such detail and depth.

        Dr. Greger also addressed this topic briefly at the end of his QandA this month. He also stated he would need to dig a little deeper.

        Well done

      2. Marcello, this is a new study, too new for most vegan sources to have responded to, but not so new that popular magazines and some of my Facebook friends are not already all over it, chortling with newly self-assured glee. Nothing gets clicks quicker than a headline telling people THEY’RE okay as they are, and those who smugly criticize any part of their thinking are deluded.

        Happily, Mic. the Vegan, among the nimblest of evidence-based vegans, has already addressed some of the flaws in this study, among the biggest being drastically inadequate correction for population differences. He addresses the funding thing, too.

    2. The study was called the Prospective Urban Rural Epidemiology diet, a cumbersome and uninformative title apparently cobbled together just to create the acronym “PURE.” Similar observational studies have been refuted often; I suspect the flaws in this one will be similar, but haven’t seen the details. Other such studies are marred by scant attention to the TYPE of carbohydrates replacing those fats; they tend to refined starches, empty calories, which prove to be approximately as detrimental to human health as the fats were. But I would, like you, appreciate a prompt refutation by Dr. Greger and others.

      1. Hi John, thank you for your reply. I realize Dr. Greger and the team have not had a chance to reply yet, but on YouTube Mic the Vegan did a very good job of refuting this study. Sorry I couldn’t attach it, but it should be easy to find.

        1. Thanks, Lori. Just saw it and posted it here just before seeing your response. Mic. is one of my go-to guys, along with Dr. Greger and Dr. McDougall.

    3. Dr. Greger said on his latest q&a that he has a whole series of videos coming up on ketogenic diet and fasting. He said he would go over the pros and cons.

  11. 300 out of 2000 . Get your head out of the sand. This is a compelling ratio. I’m pretty sure Dr. G would be intrigued. Another example is Sardinia .Sardinians’ diet is particularly rich in proteins derived from milk and cheese, while low on sugary food and meat. Many of them eat meat only once or twice a week. The dishes are usually a small piece of lamb, lean pork, oily fish or shellfish accompanied by a lot of vegetables. The rate of centenarians is about 20 times that found in the USA. Don’t take my word for it, Do some research.
    The Mediterranean diet is NOT vegan.Vegans have terrible homocysteine levels? Again, not supported by any evidence. DID YOU WATCH THE VIDEO?
    Observing populations on their traditional diet is valid and compelling.
    I defy you to show me a study that says their diet leads to early death. Have a look at the statistics for these populations
    Q. How do you know if someone is vegan?
    A. They’ll tell you
    Dr. G often compares results to” the standard American diet”. My perception of that is pizza, chips with everything (Deep fried in rancid , oxidised polyunsaturated fat ) shakes, burgers , twinkies . Let’s not forget portion size. A small size would be large in other countries. My son travelled in the states recently and found it challenging in some regions to find decent food that we take for granted. Heavily processed etc.

  12. I have been a “healthy” omnivore my entire 51 years. Very active and engaged in life. My mom cooked/served lots of veggies, I cook/serve lots of veggies. Whole grains..everything homemade. Sweets in moderation only homemade. Meat regularly. Lots of fish. Tofu regularly. Nothing deep fried..well maybe rarely! A true omnivore. And I never could understand why my cholesterol and triglycerides were always through the roof. I didn’t understand how I could get breast cancer at 40– three invasive tumors. I ate what is traditionally thought as so healthy. Exercise, never more than 10 lbs overweight. Chest pains and having so much fatty deposits in my eye that I lost most of my vision made me seek out a change. Statins made me get muscle pain and scared me. So..enter Dr Greger. “Might be something in your diet rather than what you are lacking from your diet” changed my life. Nothing lacked in my diet. Take away almost all my intake of dairy, eggs and meat? Finally, finally. My numbers are coming down steady and normal is within sight(though I’m looking to be less than normal) I’m okay being 98% plant based and saving a little wiggle room, though. I feel amazing. I’m losing my last ten pounds with no effort. I eat so much, never hungry. Cravings minimal for any crap, esp sweets. I think I have bad genetics and this is helping turn off those genes. Maybe others with great genes can afford to be an omnivore, I cannot. Thank you Dr Greger from the bottom of my heart. My mom’s family all died in their 60s from cancers. My dad’s side died ages 40-51 from heart disease. And not from the standard American diet but from a truly healthful omnivore diet. With my cholesterol coming down so wonderfully, it’s obvious it was what I was including not what I wasn’t getting enough of.

  13. Hey Jeff,

    Thanks for your question! Right off the bat, I was suspicious of this study (remember; people love to hear good news about their bad habits). Dave Asprey and the bulletproof company make money by selling butter, so, naturally, they would share this kind of study and call it a “confirmation” of their philosophy.

    Unfortunately, this article is only able to be accessed to the general public by paying $32. I have access to the article through my profession so I was able to review it.

    At no point in the study do the researchers address what actual foods the participants were consuming. We are left to wonder if the high-carb diet participants were eating sweet potatoes and whole grains, or candy and refined pasta. Likewise, we have no idea if the high-fat participants were eating avocados and nuts, or butter and meat.

    That being said, I have absolutely no idea how Dave Asprey and bulletproof came to the conclusion that “meat and butter can lead to a longer life.” Meat and butter were not once addressed in this study.

    Thinking of foods in terms of the macronutrients that they are primarily composed of, rather than considering all of the different nutrients they contain, is a very flawed approach to healthy eating. Both skittles and blueberries are considered to be “carbs.” They have a tremendously different impact on our bodies.

    Ironically enough, Dave Asprey has complained in the past that the hundreds of epidemiological studies that show a strong relationship between plant-based diets and longevity are invalid, because they show correlation and not causation. This study is epidemiological in nature as well, and can’t “prove” anything by itself. In order to make strong suggestions such as “global dietary guidelines should be reconsidered in light of these findings,” there need to be dozens and dozens of studies that elicit similar findings. I wasn’t able to find any other peer-reviewed studies that had similar findings. On the contrary, a plant-based diet has been repeatedly shown in peer-reviewed studies to be positively correlated with increased lifespan, decreased chronic disease, and has even been shown to reverse heart disease (in the Ornish study).

    I hope this helped. Sorry for the length :)

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