Charismatic Paleo Bloggers: Rigorous Caution Required

Paleo Bloggers | The Paleo Diet


Some of the most well recognized names in the “Paleosphere” surprisingly maintain few professional, academic, or even experiential credentials which would qualify them as scientists, researchers or even lay experts in the discipline. These self proclaimed, charismatic authorities have influenced and continue to influence hundreds of thousands of people based upon nothing more than their untested subjective opinions and limited understanding of the scientific, peer review literature.

Most have never been trained in the research process, few maintain anything  more than a bare bones understanding of the scientific method and don’t have even the slightest inkling of the statistical or research design issues that can make or break the validity and generalizability of any scientific study. Universally, none of these influential Paleo bloggers have an extensive publication record in the scientific peer review literature relating to Paleo diets or anything else.

Accordingly, their blogs have no origins in their own prior refereed scientific writings (because they don’t have any).  Unfortunately, these bloggers can utter just about anything they desire about contemporary Paleo diets because virtually no objective system of checks and balances underlie their writings and opinions.


The difference between charismatic bloggers and published research scientists is that the latter must present their ideas, work and experiments before a panel of scientific peers prior to publication. The peer review process certainly is not infallible and clearly does not always insure the accuracy, generalizability or validity of any experiment or idea. Nevertheless, it generally does insure that the paper or concept has been examined by a panel of scientists and experts who usually are trained in the discipline, but who also are typically trained in universal research design and statistical concepts and procedures, without which experiments and data are meaningless and un-interpretable.

Almost universally, charismatic bloggers have little or no understanding of how research design and statistical issues can make or break the interpretation of any experiment or hypothesis, yet as I will show you they proudly offer their opinions regardless.


I graduated from the University of Utah in 1981 with a Ph.D. in Health Sciences (emphasis: Exercise Physiology).  Besides course work, one of the requirements for the Ph.D. was the successful completion of an experimental project and the subsequent write-up of this research via a Doctoral Dissertation. During my years of coursework, I took almost two quarters worth of specific graduate level classes that focused upon 1) a variety of statistical procedures, 2) research design issues, and 3) computer assisted data compilation and interpretation. Whew! These classes were not fun, and I struggled to get through some of them. But without the knowledge and experience I gained from these classes, I wouldn’t have had a clue about designing, statistically analyzing, and writing up the physiological/respiratory experiment that eventually became my Doctoral Dissertation.

When I finally completed my two year long experiment, wrote the dissertation and finally graduated, I breathed a sigh of relief in the mistaken belief that I would never again have to go through this ordeal. Wrong! At the time, little did I realize the research design, statistical and computer skills I had utilized for my Ph.D. project would never leave me, and that I would have to repeat this process again, again and again on a regular basis for the next 32 years.

It is sometimes said that the best way to better learn about any topic or skill is to have to teach it to others. As a rookie, Assistant Professor at Colorado State University in the fall of 1981, I was immediately assigned to teach a graduate course in Research Design and Statistics to both Master’s and Ph.D. students. As it turned out, I would go on to teach this course for the next 32 years, but more importantly I continually honed my research design and statistical tools not only for my own research, but also as I taught my graduate students to implement their research projects. Increasingly as my career developed I fully appreciated the magnitude of these powerful scientific tools as I served as a reviewer for scientific journal articles and governmentally sponsored grants.

“By using it, you will not lose it,” or so goes the truism.  In the case of research design and statistics, almost all charismatic bloggers, never learned these scientific tools in the first place, so their Paleo diet interpretations of the scientific literature and subsequent subjective pronouncements need to be rigorously evaluated if we are to place any credence whatsoever upon their writings.

Below are just a few key questions almost any scientist familiar with research design and statistical procedures would be able to answer. I suspect that none of our charismatic Paleo bloggers whose names you all recognize would be able to answer any of these questions off the top of their heads. Familiarity with these concepts is essential in correctly interpreting and fully understanding the scientific literature.


  1. What is statistical power and how does it influence hypothesis testing?
  2. What is the null hypothesis. Can it be answered in either the affirmative or negative or only singly and why does it matter?
  3. What is a two-tailed statistical test? How does it affect alpha and subsequently hypothesis testing?
  4. What is the relationship between alpha (a type 1 statistical error) and beta (a type 2 statistical error) and how does sample size (n) interact with these concepts to affect hypothesis testing?
  5. Why is sample size crucial when evaluating the internal and external validity of an experiment?
  6. What are the four levels of data and how does this information influence the type of statistic to be employed in the analysis and why?
  7. What are the differences among 1) pre-experimental, 2) quasi experimental and 3) true experimental designs. How do these considerations influence internal validity and generalizability of the experiment?
  8. When is a repeated measures ANOVA used to analyze data and why should multiple t-tests not be used in making repeated comparisons?
  9. What are the differences between parametric and non-parametric statistical tests and how does the level of data influence their choice?
  10. Do descriptive statistics show causality? How about inferential statistics? What are common differences between the two?
  11. Is it possible to generate a standard deviation greater than the mean? How are large standard deviations generally interpreted with small sample sizes?  How about with large sample (n) sizes?
  12. When should the standard error of the mean (SEM) be employed in lieu of the standard deviation?
  13. With the inclusion of more and more variables into a forward, stepwise multiple regression equation, what is the effect upon “R”; what is the effect upon “p”. Why does this matter?
  14. How does the use of partial correlation techniques help to unravel relationships among a series of variables?

OK, OK – ENOUGH! You get my point; we could go on endlessly with these obscure statistical and research design concepts. For most of you, not only can you not answer these questions, the answers are irrelevant anyway.

What you want to find out from your charismatic blogger is a simple answer to a simple question – should I drink milk or not? How about kefir? Should I regularly consume legumes and beansHow about sea salt – is it OK? Do contemporary Paleo diets require supplements?

I’ll give you some insight into your charismatic blogger – off the top of their heads, without the input of skilled professionals, they could not answer these research design and statistical questions either – they simply lack the training. Like you, they are barely even familiar with these terms and concepts known to most research scientists.

Without the knowledge or understanding of research design and statistical notions our charismatic, influential Paleo bloggers simply cannot understand the subtleties, limitations and flaws in the scientific papers they may read. Accordingly, their advice and pronouncements about a variety of Paleo Diet issues are at best incomplete, and at worst flat out wrong.


One of the challenges faced by nutritional scientists when they ultimately make recommendations regarding what we should and should not eat is to establish cause and effect between a dietary element and the subsequent development or prevention of disease. Some foods and some dietary habits promote good health whereas others promote disease. Figure 1 demonstrates the four primary procedures by which causality is established between diet and disease.1, 2

Figure 1

Figure 1. The four primary procedures by which causality is established between diet and disease.1, 2

No single procedure alone can establish cause and effect,1, 2 nor can any single study prove causality.3 Observational epidemiological studies can only show relationships among variables and are notorious for showing conflicting results4 and cannot provide decisive evidence by themselves either for or against specific hypotheses.5

For example increased animal protein has been associated with a decreased risk for coronary heart disease (CHD) in a large group of nurses (The Nurses Health Study),6 whereas exactly the opposite association was found for markers of CHD and meat consumption in people from rural China.7, 8 An analogy here may be appropriate to show you why observational epidemiological studies can only show relationships and not establish causality. In New York City, there is a strong association between the size of a structure fire and the number of fire trucks at the fire, but can we conclude that more fire trucks cause bigger fires?

In order to establish cause and effect between diet and disease, it takes more than just observational epidemiological evidence.5 There must also be what is referred to as “biological plausibility” in which evidence gathered from tissue, animal and short term human metabolic studies support causality.2 When observational epidemiological evidence is augmented by biological plausibility studies and confirmed by randomized controlled human trials, the case for causality becomes ever more convincing. Unfortunately, charismatic Paleo bloggers seem to be unaware of these basic research design parameters when they read, evaluate and report upon the scientific nutritional literature.


Over the past five or six years, The Paleo Diet, has grown into a household concept known to millions of people worldwide and has beneficially affected the health and wellbeing of countless individuals. Nevertheless, the original message, developed primarily in the scientific literature, has now increasingly become diluted as certain charismatic, non-scientific bloggers turn the original concept into a non-factual, personal belief system without consensus or support by the scientific Paleo Diet literature.

If your charismatic Paleo blogger promotes any of the following nutritional guidelines below, you may want to rigorously research each of these concepts for yourself and then reconsider these so-called “experts” as spokespersons for contemporary Paleo diets.


These four guidelines promoted by charismatic Paleo bloggers have been debunked and are not part of a real Paleo Diet:

  • Dairy products can be a regular components of contemporary Paleo diets.
  • Sea salt can be used in lieu of regular table salt in contemporary Paleo diets.
  • Legumes and beans are nutritious foods and should be regularly included in contemporary Paleo diets.
  • Contemporary Paleo diets cannot be successfully implemented without the use of various supplements or supplement mixtures conveniently concocted and sold only by your friendly charismatic Paleo blogger.*

* Clearly humans are no longer wild hunter-gatherers and in the 21st century we are definitely operating in a foreign niche. Consequently, a few dietary exceptions are required.

Most of us stay indoors in buildings 24/7, whereas our ancestors had no such thing as “indoors.” Accordingly, to insure our blood concentrations of Vitamin D are equivalent to our outdoor living ancestors, we need to either sunbathe regularly or supplement with Vitamin D.

If we eat fatty fish (salmon, herring, mackerel, sardines, etc.) 2-3 times per week, there is absolutely no need to supplement with fish oil. Nevertheless, a significant number of people in westernized countries don’t like or can’t afford fresh fish. Hence the need to supplement with fish oil, so that our blood concentrations of long chain omega 3 fatty acids are comparable to our pre-agricultural ancestors who ate the entire carcass of their prey animals (brains, gonads, liver, kidney) which are highly concentrated sources of long chain omega 3 fatty acids. For most westerners it is culturally offputting and not consistent with our modern tastes to regularly eat brains etc.

The calcium issue is a tricky whicket, but we have devoted an entire blog and soon to be peer review scientific paper on this topic: “Got Bones? The Paleo Solution for Building Strong Bones While Keeping Arteries Soft and Supple” Evolution through natural selection has completely figured out the calcium conundrum in hominins from 2 MYA until the agricultural revolution. Outdoor living in a wild environment to which we are genetically adapted solves the calcium issue. Modern people who habitually consume salt (whether Paleo or not), unless they consume fresh fruits and veggies daily to the tune of about 25-35 % of energy may require calcium supplements.


  1. Sempos CT, Liu K, Ernst ND. Food and nutrient exposures: what to consider when evaluating epidemiologic evidence. Am J Clin Nutr. 1999 Jun;69(6):1330S-1338S.
  2. Potischman N, Weed DL. Causal criteria in nutritional epidemiology. Am J Clin Nutr. 1999 Jun;69(6):1309S-1314S.
  3. Freudenheim JL. Study design and hypothesis testing: issues in the evaluation of evidence from research in nutritional epidemiology. Am J Clin Nutr. 1999 Jun; 69(6): 1315S-1321S.
  4. Fraser GE. A search for truth in dietary epidemiology. Am J Clin Nutr. 2003 Sep;78(3 Suppl):521S-525S.
  5. Flegal KM. Evaluating epidemiologic evidence of the effects of food and nutrient exposures. Am J Clin Nutr. 1999 Jun;69(6):1339S-1344S.
  6. Hu FB, Stampfer MJ, Manson JE, Rimm E, Colditz GA, Speizer FE, Hennekens CH, Willett WC. Dietary protein and risk of ischemic heart disease in women. Am J Clin Nutr. 1999 Aug;70(2):221-7.
  7. Campbell TC, Junshi C. Diet and chronic degenerative diseases: perspectives from China. Am J Clin Nutr. 1994 May;59(5 Suppl):1153S-1161S.
  8. Campbell TC, Parpia B, Chen J. Diet, lifestyle, and the etiology of coronary artery disease: the Cornell China study. Am J Cardiol. 1998 Nov 26;82(10B):18T-21T.

About Loren Cordain, PhD, Professor Emeritus

Loren Cordain, PhD, Professor EmeritusDr. Loren Cordain is Professor Emeritus of the Department of Health and Exercise Science at Colorado State University in Fort Collins, Colorado. His research emphasis over the past 20 years has focused upon the evolutionary and anthropological basis for diet, health and well being in modern humans. Dr. Cordain’s scientific publications have examined the nutritional characteristics of worldwide hunter-gatherer diets as well as the nutrient composition of wild plant and animal foods consumed by foraging humans. He is the world’s leading expert on Paleolithic diets and has lectured extensively on the Paleolithic nutrition worldwide. Dr. Cordain is the author of six popular bestselling books including The Real Paleo Diet Cookbook, The Paleo Diet, The Paleo Answer, and The Paleo Diet Cookbook, summarizing his research findings.

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“20” Comments

  1. Very confused by the end of the article:
    there is then a list, a blank line, with more bulleted points following —
    it is unclear to me what is meant to be true here, and what myth.

    • Thanks for the feedback! Looks like the formatting of the last part of the article fell apart a bit. It’s fixed and should be a lot clearer now.

  2. I have recently been diagnosed with an autoimmune disease. My question is: if I pressure cook tomatoes, does it reduce the lectin content significantly? Some websites say they do, others are silent on the topic. I don’t eat tomatoes often, but sometimes I need to use them in my cooking, so I wanted to check. Thanks!

  3. We also have to be very careful about how much emphasis and reliability we give to the peer review process. Professor Cordain should remember the study that was peer reviewed and indicated that starches were responsible for our big brains. Cordain was critical of the peer review process in that instance.

  4. It’s a pity you don’t have a donate button! I’d definitely donate to this excellent blog!

    I suppose for now i’ll settle for bookmarking and adding
    your RSS feed to my Google account. I look forward to
    fresh updates and will share this website with my Facebook group.
    Talk soon!

  5. I’ve read all of your books and many other books by many physician’s biochemists, researchers etc., etc. I have read the books of many of the bloggers you are referring to as well. What I find interesting is how many physicians with excellent credentials, such as yourself, completely and utterly disagree with everything you say and think you are a quack. I don’t agree but I think you are being a bit arrogant to think that only your research is valid. One thing I believe is that there is no one diet that is best for everyone. There are many cultures that eat many of the foods you are against and live long, disease free lives. I don’t like when others bash and try to discredit your work but I also don’t like when you do the same to others. After reading The Paleo Diet and The Paleo Answer I followed your advise for several years and developed osteopenia, suffered from insomnia and my LDL cholesterol went up significantly. After reintroducing some kefir and other dairy products my last bone density scan showed much improvement and I also sleep much better now. I’ll see what my LDL shows when I get my blood tests done again.

    • Michelle, Dr. Cordain is far from being arrogant. He doesn’t claim to be right or to own the truth. He never said statements like “nobody should drink dairy because is definetly bad”. Using the powerful evolutionary tool together with some hints coming from research, he stated that caution is required because the questioned food has got molecules that may be harmful. Since we don’t need neolithic foods to achieve good health, logic says that there would be no need to take the risk of a potential harm when there are highly nutritional foods that nourished us for hundreds of thousands years.Why do the mainstream charismatic bloggers encourage dairy, legumes etc? Dairy are tasty and you can catch up more persons and sell your idea and products. Furthermore, as soon as the paleo diet has been patented, they have to find a similar approach but not the same. Cordain is not claiming that they are wrong, he’s saying that nobody actually knows, but you think with your own head, it’s up to you to decide how much risk you want to take in your life. Health is not black and white, there are many shades of what we define as well being. We’ve seen that there are some cultures like Masai that may be relatively healthy drinking milk (that is not however like the UHT milk you find in the supermarket), but there’s also one debated study that shows that they have artheries clogged in elder age and they are weaker than us, all the other way around of our ancestors. Of course if you compare them to the obese average american stuffed with all the possible junk food, any being eating real food is much healthier, but this doesn’t imply that is the best for our species. The phylosophy behind the real paleo diet is “it’s better to avoid the unnecessary danger unless proof”, while the claim of some other alleged experts is more or less based on a gray risky area built to sell books, consultation (the more you personalize and are uncertain the more you need my advises, i.e. money) for clinicians. They only base that this or that is good for you on empirical trials, it may not be necessarily bad but it may not work every time in a world where the confounding variable is the norm rather than the exception.

      • The fact is that there’s no reliable research that supports the hypothesis that dairy consumption is safe, while there are many hints that suggest that may be harmful and they are indeed one of the most allergenic and immunogenic food together with wheat. Then if you sometimes cook with some grassfed butter and you are relatively healthy, it’s unlikely that you are gonna fall dead right away. Logic says “avoid the danger if not necessary” not all the other way around. Ironically, some core scientists that have been the head of famous paleo bloggers, state that dairy may be worth but when you ask them what they eat it comes out that they eat meat, eggs, veggies and some sweet potatoes skipping dairy.what a coincidence that their self personalization trial found that dairy is not good for them and prefered to stick to the essentials of a more “real” paleo diet.

        • The last example: there is some research that seems to support the idea that kefir is a very good probiotic (mostly funded by kefir sellers) but there are other research that lactibacillus acidophilus (one of the main bacteria in kefir) may at best do nothing and in some cases be harmful. What does caution says? To get it liberally or to try an alternative less controverse?

  6. It’s right to defend a good and pure idea and it deserves success.
    I know it’s very hard to achieve such goals in our industrial fake world and pure and brave projects deserve great respect and support

  7. Dear Greg, thank you very much for your response. I wish you excused me because I got it wrong. Instead of checking what it actually was, I assumed that it was like some industrial “paleo” meals and snack I’ve found elsewhere. The lesson is to double check before speaking, if you manage to deliver fresh pasture raised and organic food without preservatives, you got it right and I admire you for your great job. I’m very sorry for my misunderstanding and I want to thank you for your kind words and explanation, I wish all the best for your project.

    • Hi Alessio,

      Thank you for your kind response. I hope I didn’t offend you with my post, I sometimes get defensive over out food because our team works so hard to make sure it is genuinely healthy and Paleo with a minimal carbon footprint.

      Thank you for your best wishes, I really appreciate it!

  8. Prof. Cordain – I have a question regarding the present post. I really hope you find the time to answer.

    You talk about Paleo Gurus lacking proper scientific education and I think you are, mostly, correct. But, what about people who have actual clinical experience with patients ? I’m not talking about the majority of those bloggers but about a few that have a constant practice and actually take care of patients.

    These people sometimes use supplements to target a specific condition and usually for a limited time period.
    If someone used to smoke for 20 years – he probably has many nutritional defficiencies that would take forever to mend with diet only – why not use supplements in a situation like this one and in other, similar cases ?

  9. I have a huge respect for Cordain’s work and I agree with all that he writes in his books. However, to be sincere, I’ve been a bit disappointed to see pseudo paleo meals and snack advertised in the paleo diet website…the second issue that led to some misleading in my opinion was about the explanation of evolution that Mr. Cordain obviously know very well but in the book could be in someway attacked by some alleged “debunkers”. In truth, they attached to a “logic” trick to state that “new” doesn’t necessarily imply “bad” and to justify that, they use the same claims of mrs. Zuk taking crude mutations and simple epigenetic mechanisms to state that we can in someway evolve. This is not false, but we should talk about the likelihood to change in addition to the timescale and the selective pressure. It can happen that a crude mutation or epigenetic change can allow to deal in someway with a certain molecule in a food, but non species specific food has usually got N problems, like milk which issue is not just about lactose. They should prove that we have the enzymes to deal with casomorphins and all the other compounds, they should prove that there could be a mutation to make possible the birth of an enzyme to break down gluten in grains, phytates and antinutrients etc…thus, these mutations would imply to turn into a different species closer to granivores going strongly against the best theories of speciation and hardly supported by evidence. The burden is to prove that a new food is good, not all the other way around. It may be possible and likely that our species would never develop a physical structure to really thrive on grains, legumes and dairy, though some degree of better individual “tolerance” has been observed. Let’s look at the Panda bear, that started millions of years ago to eat bamboo and it seems that it never develop a full adaptations that might allow to break down cellulose efficiently. Thus, it’s not so likely to turn into birds for us. This for me is the issue should be discussed together with the timescale. And Mr.Lalonde pointed out unproven theories to debunk mr.Cordain’s lecture about antinutrients and at the same time he developed a sterile mathematic table about nutritional facts. The evolutionary template is the starting point, and Cordain didn’t attach to it as the goal, but as a starting point to work with actual studies and empirical evidence.

    • Hi Alessio,

      First off, I think your response is great, well thought out, and is full of useful direction, especially the comments about epigenetics.

      With that being said, I want to directly ask why you are disappointed to see Paleo meals (which you referred to as “pseudo Paleo meals,” posted on The Paleo Diet site?

      The reason I ask is because I am the founder of 2 of the companies listed on the site, including Trifecta, the company that makes the Paleo meals, and we go through extensive, difficult supply chain and production processes to make sure we meet Dr. Cordain’s guidelines when it comes to Paleo. Our meat is Organic, Grass Fed, Wild Caught, etc. and all of the vegetables are Organic. We do not freeze the meals, or process them other than basic cooking and we deliver them next day air to people nationwide, who often live in food deserts where there is nothing around but McDonald’s or Wal-Mart.

      I do not know you at all, so I will not make any judgements about you as you have about my companies. What I do know is that we put an extreme amount of effort into our businesses to be able to provide genuinely healthy and genuinely Paleo food that is directly overseen by Dr. Cordain to people nationwide who are often in desperate need of a healthy option (health reasons, medical reasons, food deserts, or even too busy, etc.).

      What makes our meals “pseudo Paleo”? And why is it a bad thing for Dr. Cordain to partner with companies on the same mission as him attempting to fight the global health crisis caused by processed food? It baffles me that our biggest critics are often those within the Paleo community that we are somehow “not Paleo enough” because we use packaging or shipping, when they are headed down to Whole Foods to buy the same exact meat and veggies we use, in the same exact packaging (which causes a substantially larger carbon footprint by the way, because of all of the additional steps in the supply chain).

      Please let me know how we can improve to make our food “more Paleo” than it currently is.

      Thank you.

  10. Hi, Dr. Cordain!

    I noticed that your posts are not dated. Information changes so quickly today. I would find it helpful for the posts to be dated. Perhaps they are and I am missing it.

    The Paleo Diet in all its entirety or un-entirety has helped many. I am grateful for that. Your work is invaluable to practitioners (and even brave patients) who can take it and tweak it for the art of medicine.

  11. Can you expound upon each of those “myths”? I.e. Why is milk/dairy bad (what about fermented and raw?) and I had never heard the thing about sea salt. You’re saying we need iodized table salt? Some clarification on 1-3 would be helpful. It’s great to point out the in-expertise of these bloggers and their commonly touted “myths” but it’s a bit fallacious if you don’t say WHY those “myths” are not true.

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