Evolutionary Aspects of Obesity, Insulin Resistance, and Cardiovascular Risk

paleo diet, Paleolithic diet, hunter-gatherer diet

Huaorani hunter in Ecuador

Spreadbury and Samis have a review-type article in Current Cardiovascular Risk Reports. Here’s the abstract:

Cardiovascular disease (CVD) is still virtually absent in those rare populations with minimal Western dietary influence. To date, exercise, altered fats, fibre, anti-oxidants or Mediterranean diet do not appear to overcome the discrepancy in CVD between hunter-gatherer and Western populations. The CVD risk factors of obesity and diabetes are driven by increased caloric intake, with carbohydrates potentially implicated. Paradoxically, non-Westernized diets vary widely in macronutrients, glycemic and insulinemic indices, yet apparently produce no obesity or CVD regardless, even with abundant food. ‘Ancestral’ grain-free whole-food diet may represent the best lifestyle intervention for obesity and CVD. Such diets are composed of the cells of living organisms, while Western grains, flour and sugar are dense, acellular powders. Bacterial inflammation of the small intestine and vagal afferents appears a crucial step in leptin-resistance and obesity. Therefore it may be important that the Western diet resembles a bacterial growth medium.

You may remember Spreadbury’s name from his theory about acellular carbohydrates causing obesity via alterations in gut microorganisms. Spreadbury is with the Gastrointestinal Diseases Research Unit, Queen’s University, Kingston, Ontario, Canada.

You can read the articles for yourself. The following are a few of the authors points I found interesting or want to remember.

Does physical activity explain differences in CVD between Westernized and non-Westernized Peoples? They say “maybe.”

Throughout the article are references to aboriginals like the Hadza, Kitavans, Ache, Shuar, Australian aborigines, and Inuits. I always take comparisons of them to modern Europeans with a grain of salt, because of potential genetic differences between the populations. Moreover, diet and activity levels are only two of myriad cultural differences.

Australian Aborigine in Swamp Darwin

Australian Aborigine in Swamp Darwin

Can dietary changes reduce the incidence of CVD? They say it’s unclear.

Regarding modern paleo diet trials, “All the studies with ad libitum eating [eat all you want] have reported a spontaneous reduction in caloric intake in the order of 15-30%.” (Three references.) “The reduced food intake appeared driven by a satiety increase that was apparently not explicable by energy density, fiber or macronutrient content.” (One reference.)

“In those eating a Westernized diet, carbohydrates are increasingly recognized as being associated with poor metabolic health.” Evidence? Only one reference cited: Zienczuk’s 2012 article on high arctic Inuits.

“…non-Westernized populations with excellent metabolic and cardiovascular health almost invariably have negligible dietary contribution from grains, as well as refined sugar.” No citations.

“For ‘western-style’ diets and most obesogenic diets tested, gut microbiota appear to play a crucial role in obesity.” That’s a bold statement. References? Only one, a mouse study.

The rest of the article is about Spreadbury’s acellular carb/obesity theory. He suggests that small intestine bacteria play a more prominent role than colonic germs. Bacterial-driven inflammation….

The authors provide an example of a grain-free whole-food diet. It’s unrestricted in fruit, leafy or root vegetables, unprocessed meats, eggs, fish, nuts (except peanuts), mushrooms, herbs and spices. Occasional foods to be eaten in moderation are legumes, rice, yogurt, milk, cheeses, sweet corn, palm oil/lard/olive oil, and salt. Avoid almost all processed foods, breads, cereals, cakes/cookies/donuts etc., refined sugars, dried or processed fruits, vegetable/seed oils, and processed meats. They advise a vitamin D supplement. I’m not sure if they came up with this diet on their own, or it’s S. Lindeberg’s outline.

A final quote:

The macronutrient independence of the health from ancestral diet suggests whole foods are more important to health than their macronutrient or other chemical components, and that good health is associated with unprocessed cellular foods. Flour, sugar and processed foods appear to be important drivers of Western metabolic dysfunction, overweight and inflammation, and may prove to have a profound impact on, or even be the initiators of cardiovascular disease.

I’m sure Spreadbury and Samis would agree we need more basic science and clinical research into these issues, involving human test subjects. Maybe I’m prejudiced, but I’m more interested in Asians, Africans, and Europeans than Shuar people.

Steve Parker, M.D.

Reference: Spreadbury, Ian and Samis, Andrew J.S. Evolutionary aspects of obesity, insulin resistance, and cardiovascular risk. Current Cardiovascular Risk Reports, April 2013, vol. 7, issue 2, pp. 136-146.

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10 responses to “Evolutionary Aspects of Obesity, Insulin Resistance, and Cardiovascular Risk

  1. Hi Steve,

    You mention the comments to another post that potatoes would be considered acellular carbohydrates but Spreadbury lists potatoes as ancestral. You also that since potatoes a acellular Jaminet would consider them ‘safe’. Is this a typo? Shouldn’t potatoes be cellular (Spreadbury also mentions tubers as allowed)?

  2. Hi Steve,

    I agree about the thin referencing. We were on a strict word and reference limit, and had an awful lot of ground to cover from the remit we’d been asked to follow (this was an invited review). This review wasn’t trying to add much new in terms of broad background on the effects of non-western diets, or to be particularly compelling in a stand-alone sense – that’s done so much better elsewhere. The real aim was a more user-friendly explanation of the microbiome-dietary refinement interaction hypothesis, I couldn’t pass up the opportunity as the first paper was unavoidably rather dense.

    Oh, and yes, boiled potatoes appear to be cellular from the electronmicroscopy I’ve seen, although I’ve no idea whether saponins or other concerns some raise about them make them ideal for all.

    Ian

    • Many thanks for the comment, Ian. I think you’re on to something good with this line of investigation. (For those who don’t read the full article, be aware that it has about 100 references as is.)
      -Steve

  3. Someone has put this paper on Googledocs https://docs.google.com/…/0B5ZeoGwPHPA8Sm91ZUFWUG9…/edit
    Spreadbury’s slide presentation is also online http://drdobryrx.com/wp…/uploads/2014/06/Spreadbury.pdf
    There is also a 5 part presentation on You Tube here is a link to the first.

    It is also worth bearing in mind the micronutrient density of grains has declined with increasing yield and this is projected to continue with increasing carbon levels.

    http://www.ncbi.nlm.nih.gov/pubmed/24867639

    Hidden shift of the ionome of plants exposed to elevated CO2 depletes minerals at the base of human nutrition.

  4. I am more interested in Asians, African, and Europeans than the other, too. I also see the similarity in the dietary recommendations to those of S. Lindeberg with the exception of plenty of coconut. Also, like the previous commenter, what about white potatoes? They seem to spark joint/foot pain in me. What about Asians who eat tons of white rice and seem fit? I confess I haven’t read the paper and will but it seems very interesting and promising. Does it seem odd to you that they focus more on the small intestine than on the large intestine? I am very interested in the new study of gut bacteria vis a vis obesity and overall health.

    • Cathy, the reference to small intestinal microorganisms caught my eye because I thought the small intestine was relatively sterile. That’s apparently true only in comparison to the large intestinal microbiome.
      When I see references to the potentially important role of the gut microbiome, I naturally think of the large intestine (colon). That’s only part of the picture.
      -Steve

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