Paleolithic diet

Wild fruit is an important feature of the diet

The Paleolithic diet, Paleo diet, caveman diet, or stone-age diet[1] is a modern fad diet[2] requiring the sole or predominant consumption of foods presumed to have been the only foods available to or consumed by humans during the Paleolithic era.[3]

The digestive abilities of anatomically modern humans, however, are different from those of Paleolithic humans, which undermines the diet's core premise.[4] During the 2.6-million-year-long Paleolithic era, the highly variable climate and worldwide spread of human populations meant that humans were, by necessity, nutritionally adaptable. Supporters of the diet mistakenly presuppose that human digestion has remained essentially unchanged over time.[4][5]

While there is wide variability in the way the paleo diet is interpreted,[6] the diet typically includes vegetables, fruits, nuts, roots, and meat and typically excludes foods such as dairy products, grains, sugar, legumes, processed oils, salt, alcohol or coffee.[1] The diet is based on avoiding not just processed foods, but rather the foods that humans began eating after the Neolithic Revolution when humans transitioned from hunter-gatherer lifestyles to settled agriculture.[3] The ideas behind the diet can be traced to Walter Voegtlin,[7]:41 and were popularized in the best-selling books of Loren Cordain.[8]

Like other fad diets, the Paleo diet is promoted as a way of improving health.[2] There is some evidence that following this diet may lead to improvements in terms of body composition and metabolic effects compared with the typical Western diet[6] or compared with diets recommended by national nutritional guidelines.[9] There is no good evidence, however, that the diet helps with weight loss, other than through the normal mechanisms of calorie restriction.[10] Following the Paleo diet can lead to an inadequate calcium intake, and side effects can include weakness, diarrhea, and headaches.[3][10]

History and terminology

According to Adrienne Rose Johnson, the idea that the primitive diet was superior to current dietary habits dates back to the 1890s with such writers as Dr. Emmet Densmore and Dr. John Harvey Kellogg. Densmore proclaimed that "bread is the staff of death," while Kellogg supported a diet of starchy and grain-based foods.[11] The idea of a Paleolithic diet can be traced to a 1975 book by gastroenterologist Walter Voegtlin,[7]:41 which in 1985 was further developed by Stanley Boyd Eaton and Melvin Konner, and popularized by Loren Cordain in his 2002 book The Paleo Diet.[8] The terms caveman diet and stone-age diet are also used,[12] as is Paleo Diet, trademarked by Cordain.[13]

In 2012 the Paleolithic diet was described as being one of the "latest trends" in diets, based on the popularity of diet books about it;[14] in 2013 the diet was Google's most searched-for weight-loss method.[15]

Like other fad diets, the paleo diet is marketed with an appeal to nature and a narrative of conspiracy theories about how nutritional research, which does not support the supposed benefits of the paleo diet, is controlled by a malign food industry.[2][16] A Paleo lifestyle and ideology have developed around the diet.[17][18]

Foods

The diet advises eating only foods presumed to be available to Paleolithic humans, but there is wide variability in people's understanding of what foods these were, and an accompanying ongoing debate.[3]

In the original description of the paleo diet in Cordain's 2002 book, he advocated eating as much like Paleolithic people as possible, which meant:[19]

  • 55% of daily calories from seafood and lean meat, evenly divided
  • 15% of daily calories from each of fruits, vegetables, and nuts and seeds
  • no dairy, almost no grains (which Cordain described as "starvation food" for Paleolithic people), no added salt, no added sugar

The diet is based on avoiding not just modern processed foods, but also the foods that humans began eating after the Neolithic Revolution.[3]

The scientific literature generally uses the term "Paleo nutrition pattern", which has been variously described as:

  • "Vegetables, fruits, nuts, roots, meat, and organ meats";[3]
  • "vegetables (including root vegetables), fruit (including fruit oils, e.g., olive oil, coconut oil, and palm oil), nuts, fish, meat, and eggs, and it excluded dairy, grain-based foods, legumes, extra sugar, and nutritional products of industry (including refined fats and refined carbohydrates)";[9] and
  • "avoids processed foods, and emphasizes eating vegetables, fruits, nuts and seeds, eggs, and lean meats".[6]

Health effects

Seeds such as walnuts are eaten as part of the diet.

The aspects of the Paleo diet that advise eating fewer processed foods and less sugar and salt are consistent with mainstream advice about diet.[1] Diets with a paleo nutrition pattern have some similarities to traditional ethnic diets such as the Mediterranean diet that have been found to be healthier than the Western diet.[3][6] Following the Paleo diet, however, can lead to nutritional deficiencies such as those of vitamin D and calcium, which in turn could lead to compromised bone health;[1][20] it can also lead to an increased risk of ingesting toxins from high fish consumption.[3]

Research into the weight loss effects of the paleolithic diet has generally been of poor quality.[10] One trial of obese postmenopausal women found improvements in weight and fat loss after six months, but the benefits had ceased by 24 months; side effects among participants included "weakness, diarrhea, and headaches".[10] In general, any weight loss caused by the diet is merely the result of calorie restriction, rather than a special feature of the diet itself.[10]

As of 2016 there are limited data on the metabolic effects on humans eating a Paleo diet, but the data are based on clinical trials that have been too small to have a statistical significance sufficient to allow the drawing of generalizations.[3][6][20] These preliminary trials have found that participants eating a paleo nutrition pattern had better measures of cardiovascular and metabolic health than people eating a standard diet,[3][9] though the evidence is not strong enough to recommend the Paleo diet for treatment of metabolic syndrome.[9] As of 2014 there was no evidence the paleo diet is effective in treating inflammatory bowel disease.[21]

Rationale and counter-arguments

Paleolithic carving of a mammoth

Adaptation

The rationale for the Paleolithic diet derives from proponents' claims relating to evolutionary medicine.[22] Advocates of the diet state that humans were genetically adapted to eating specifically those foods that were readily available to them in their local environments. These foods therefore shaped the nutritional needs of Paleolithic humans. They argue that the physiology and metabolism of modern humans have changed little since the Paleolithic era.[23] Natural selection is a long process, and the cultural and lifestyle changes introduced by western culture have occurred quickly. The argument is that modern humans have therefore not been able to adapt to the new circumstances.[24] The agricultural revolution brought the addition of grains and dairy to the diet.[25]

According to the model from the evolutionary discordance hypothesis, "[M]any chronic diseases and degenerative conditions evident in modern Western populations have arisen because of a mismatch between Stone Age genes and modern lifestyles."[26] Advocates of the modern Paleo diet have formed their dietary recommendations based on this hypothesis. They argue that modern humans should follow a diet that is nutritionally closer to that of their Paleolithic ancestors.

The evolutionary discordance is incomplete, since it is based mainly on the genetic understanding of the human diet and a unique model of human ancestral diets, without taking into account the flexibility and variability of the human dietary behaviors over time.[27] Studies of a variety of populations around the world show that humans can live healthily with a wide variety of diets, and that in fact, humans have evolved to be flexible eaters.[28] Lactose tolerance is an example of how some humans have adapted to the introduction of dairy into their diet. While the introduction of grains, dairy, and legumes during the Neolithic revolution may have had some adverse effects on modern humans, if humans had not been nutritionally adaptable, these technological developments would have been dropped.[29]

Evolutionary biologist Marlene Zuk writes that the idea that our genetic makeup today matches that of our ancestors is misconceived, and that in debate Cordain was "taken aback" when told that 10,000 years was "plenty of time" for an evolutionary change in human digestive abilities to have taken place.[4]:114 On this basis Zuk dismisses Cordain's claim that the paleo diet is "the one and only diet that fits our genetic makeup".[4]

Diseases of affluence

Advocates of the diet argue that the increase in diseases of affluence after the dawn of agriculture was caused by changes in diet, but others have countered that it may be that pre-agricultural hunter-gatherers did not suffer from the diseases of affluence because they did not live long enough to develop them.[30] Based on the data from hunter-gatherer populations still in existence, it is estimated that at age 15, life expectancy was an additional 39 years, for a total age of 54.[31] At age 45, it is estimated that average life expectancy was an additional 19 years, for a total age of 64 years.[32][33] That is to say, in such societies, most deaths occurred in childhood or young adulthood; thus, the population of elderly – and the prevalence of diseases of affluence – was much reduced. Excessive food energy intake relative to energy expended, rather than the consumption of specific foods, is more likely to underlie the diseases of affluence. "The health concerns of the industrial world, where calorie-packed foods are readily available, stem not from deviations from a specific diet but from an imbalance between the energy humans consume and the energy humans spend."[34]

Historical diet

Brassica oleracea, an edible wild plant

Adoption of the Paleolithic diet assumes that modern humans can reproduce the hunter-gatherer diet. Molecular biologist Marion Nestle argues that "knowledge of the relative proportions of animal and plant foods in the diets of early humans is circumstantial, incomplete, and debatable and that there are insufficient data to identify the composition of a genetically determined optimal diet. The evidence related to Paleolithic diets is best interpreted as supporting the idea that diets based largely on plant foods promote health and longevity, at least under conditions of food abundance and physical activity."[35] Ideas about Paleolithic diet and nutrition are at best hypothetical.[36]

The data for Cordain's book only came from six contemporary hunter-gatherer groups, mainly living in marginal habitats.[37] One of the studies was on the !Kung, whose diet was recorded for a single month, and one was on the Inuit.[37][38][39] Due to these limitations, the book has been criticized as painting an incomplete picture of the diets of Paleolithic humans.[37] It has been noted that the rationale for the diet does not adequately account for the fact that, due to the pressures of artificial selection, most modern domesticated plants and animals differ drastically from their Paleolithic ancestors; likewise, their nutritional profiles are very different from their ancient counterparts. For example, wild almonds produce potentially fatal levels of cyanide, but this trait has been bred out of domesticated varieties using artificial selection. Many vegetables, such as broccoli, did not exist in the Paleolithic period; broccoli, cabbage, cauliflower, and kale are modern cultivars of the ancient species Brassica oleracea.[29]

Trying to devise an ideal diet by studying contemporary hunter-gatherers is difficult because of the great disparities that exist; for example, the animal-derived calorie percentage ranges from 25% for the Gwi people of southern Africa to 99% for the Alaskan Nunamiut.[40] Descendants of populations with different diets have different genetic adaptations to those diets, such as the ability to digest sugars from starchy foods.[40] Modern hunter-gatherers tend to exercise considerably more than modern office workers, protecting them from heart disease and diabetes, though highly processed modern foods also contribute to diabetes when those populations move into cities.[40]

Researchers have proposed that cooked starches met the energy demands of an increasing brain size, based on variations in the copy number of genes encoding for amylase.[41][42]

See also

References

  1. 1 2 3 4 "Top 5 Worst Celebrity Diets to Avoid in 2015". British Dietetic Association. 8 December 2014.
  2. 1 2 3 "Caveman fad diet". NHS Choices. 9 May 2008. Retrieved 25 December 2015.
  3. 1 2 3 4 5 6 7 8 9 10 Tarantino, G; Citro, V; Finelli, C (2015). "Hype or reality: should patients with metabolic syndrome-related NAFLD be on the Hunter-Gatherer (Paleo) diet to decrease morbidity?". Journal of Gastrointestinal and Liver Diseases. 24 (3): 359–68. doi:10.15403/jgld.2014.1121.243.gta. ISSN 1841-8724. PMID 26405708.
  4. 1 2 3 4 Zuk M (2013). Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live. W.W. Norton & Co. ISBN 978-0-393-08137-4.
  5. ↑ Henry, Amanda; Brooks, Alison; Piperno, Dolores (2014). "Plant foods and the dietary ecology of Neanderthals and early modern humans". Journal of Human Evolution. 69: 44–54. doi:10.1016/j.jhevol.2013.12.014. PMID 24612646.
  6. 1 2 3 4 5 Katz DL, Meller S (2014). "Can we say what diet is best for health?". Annu Rev Public Health. 35: 83–103. doi:10.1146/annurev-publhealth-032013-182351. PMID 24641555.
  7. 1 2 Fitzgerald M (2014). Diet Cults: The Surprising Fallacy at the Core of Nutrition Fads and a Guide to Healthy Eating for the Rest of Us. Pegasus Books. p. 38. ISBN 978-1-60598-595-4.
  8. 1 2 "The modern take on the Paleo diet: is it grounded in science?". Environmental Nutrition (7). 2010.
  9. 1 2 3 4 Manhiemer, Eric W; van Zuuren, Esther J; Fedorowicz, Zbys; Pijl, Hanno (12 August 2015). "Paleolithic nutrition for metabolic syndrome: systematic review and meta-analysis". Am J Clin Nutr. 102 (4): 922–32. doi:10.3945/ajcn.115.113613. PMC 4588744. PMID 26269362.
  10. 1 2 3 4 5 Obert J, Pearlman M, Obert L, Chapin S (2017). "Popular Weight Loss Strategies: a Review of Four Weight Loss Techniques". Curr Gastroenterol Rep (Review). 19 (12): 61. doi:10.1007/s11894-017-0603-8. PMID 29124370.
  11. ↑ Johnson, Adrienne Rose (2016). "Paleo Diets and Utopian Dreams". Skeptic. 21 (3): 11–12.
  12. ↑ Shariatmadari, David (22 October 2014). "What language tells us about the roots of the stone age diet". The Guardian. Retrieved 17 March 2015.
  13. ↑ Lowe K (20 July 2014). "A dissenting view on the Paleo Diet". The Seattle Times. Retrieved 17 March 2015.
  14. ↑ Cunningham E (2012). "Are diets from paleolithic times relevant today?". J Acad Nutr Diet. 112 (8): 1296. doi:10.1016/j.jand.2012.06.019. PMID 22818735.
  15. ↑ "Top diets review for 2014". NHS. Retrieved 24 November 2014. The paleo diet, also known as the caveman diet, was Google's most searched-for weight loss method in 2013.
  16. ↑ Hall H (2014). "Food myths: what science knows (and does not know) about diet and nutrition". Skeptic. 19 (4). p. 10. Fad diets and "miracle" diet supplements promise to help us lose weight effortlessly. Different diet gurus offer a bewildering array of diets that promise to keep us healthy and make us live longer: vegan, Paleo, Mediterranean, low fat, low carb, raw food, gluten-free ... the list goes on. (subscription required)
  17. ↑ Joseph Goldstein (January 8, 2010). "The New Age Cavemen and the City". The New York Times.
  18. ↑ Jason Wilson (March 16, 2015). "Paleo isn't a fad diet, it's an ideology that selectively denies the modern world". The Guardian. Retrieved February 5, 2016.
  19. ↑ Kim Goss for Bigger Faster Stronger. September/October 2004. Good Nutrition
  20. 1 2 Pitt, Christopher E (January–February 2016). "Cutting through the Paleo hype: The evidence for the Palaeolithic diet". The Royal Australian College of General Practitioners. 45 (1–2): 35–38.
  21. ↑ Hou JK, Lee D, Lewis J (October 2014). "Diet and inflammatory bowel disease: review of patient-targeted recommendations". Clin. Gastroenterol. Hepatol. (Review). 12 (10): 1592–600. doi:10.1016/j.cgh.2013.09.063. PMC 4021001. PMID 24107394. Even less evidence exists for the efficacy of the SCD, FODMAP, or Paleo diets. Furthermore, the practicality of maintaining these interventions over long periods of time is doubtful.
  22. ↑ Konner M.; Eaton, S. Boyd (2010). "Paleolithic Nutrition: Twenty-Five Years Later". Nutrition in Clinical Practice 25 (6): 594–602, p. 594. PMID 21139123
  23. ↑ Konner M.; Eaton, S. Boyd (2010). "Paleolithic Nutrition: Twenty-Five Years Later". Nutrition in Clinical Practice 25 (6): 594–602, pp. 594–95.
  24. ↑ Carrera-Bastos, P., Fontes-Villalba, M., O’Keefe, J., Lindeberg, S., Cordain, L. 2011. The western diet and lifestyle and diseases of civilization. Research Reports in Clinical Cardiology. doi:10.2147/RRCC.S16919
  25. ↑ Ramsden, C.; Faurot, K.; Carrera-Bastos, P.; Cordain, L.; De Lorgeril, M.; Sperling, L. (2009). "Dietary Fat Quality and Coronary Heart Disease Prevention: A Unified Theory Based on Evolutionary, Historical, Global, and Modern Perspectives". Current Treatment Options in Cardiovascular Medicine. 11 (4): 289–301. doi:10.1007/s11936-009-0030-8. PMID 19627662.
  26. ↑ Elton, S (2008). "Environments, Adaptation, and Evolutionary Medicine: Should We be Eating a Stone Age Diet?". In S. Elton, P. O'Higgins (ed.), Medicine and Evolution: Current Applications, Future Prospects. Boca Raton, FL: CRC Press. P. 9. ISBN 978-1-4200-5134-6.
  27. ↑ Turner BL, Thompson AL (2013). "Beyond the Paleolithic prescription: incorporating diversity and flexibility in the study of human diet evolution". Nutr. Rev. (Review). 71 (8): 501–10. doi:10.1111/nure.12039. PMC 4091895. PMID 23865796.
  28. ↑ Leonard, William R. (1 December 2002). "Food for Thought: Dietary change was a driving force in human evolution". Scientific American. Retrieved 20 January 2016. (Subscription required (help)).
  29. 1 2 Jabr, Ferris (3 June 2013). "How to Really Eat Like a Hunter-Gatherer: Why the Paleo Diet Is Half-Baked". Scientific American.
  30. ↑ Ungar PS, Grine FE, Teaford MF (2006). "Diet in Early Homo: A Review of the Evidence and a New Model of Adaptive Versatility". Annual Review of Anthropology. 35 (1): 209–228. doi:10.1146/annurev.anthro.35.081705.123153. ISSN 0084-6570.
  31. ↑ Hillard Kaplan; Kim Hill; Jane Lancaster; A. Magdalena Hurtado (2000). "A Theory of Human Life History Evolution: Diet, Intelligence and Longevity" (PDF). Evolutionary Anthropology. 9 (4): 156–185. doi:10.1002/1520-6505(2000)9:4<156::AID-EVAN5>3.0.CO;2-7. Retrieved 12 September 2010.
  32. ↑ Gurven, Michael; Kaplan, Hillard (2007). "Longevity Among Hunter- Gatherers: A Cross-Cultural Examination". Population and Development Review. 33 (2): 321–365. doi:10.1111/j.1728-4457.2007.00171.x. ISSN 0098-7921.
  33. ↑ Osborne, Daniel L.; Hames, Raymond (2014). "A life history perspective on skin cancer and the evolution of skin pigmentation". American Journal of Physical Anthropology. 153 (1): 1–8. doi:10.1002/ajpa.22408. ISSN 0002-9483. PMID 24459698.
  34. ↑ Leonard, William R. (December 2002). "Food for thought: Dietary change was a driving force in human evolution" (PDF). Scientific American. 287 (6): 106–15. PMID 12469653.
  35. ↑ Nestle, Marion (March 2000). "Paleolithic diets: a sceptical view". Nutrition Bulletin. 25 (1): 43–7. doi:10.1046/j.1467-3010.2000.00019.x.
  36. ↑ Milton, Katharine (2002). "Hunter-gatherer diets: wild foods signal relief from diseases of affluence (PDF)" (PDF). In Ungar, Peter S.; Teaford, Mark F. Human Diet: Its Origins and Evolution. Westport, CT: Bergin and Garvey. pp. 111–22. ISBN 0-89789-736-6.
  37. 1 2 3 Peter S. Ungar; Mark Franklyn Teaford (1 January 2002). Human Diet: Its Origin and Evolution. Greenwood Publishing Group. pp. 67–. ISBN 978-0-89789-736-5.
  38. ↑ Lee, Richard (1969). "Kung Bushmen Subsistence: An Input-Output Analysis". Contributions to Anthropology: Ecological Essays. Ottawa: National Museums of Canada (230): 73–94.
  39. ↑ Eaton, M.D., S. Boyd; Shostak, Marjorie; Konner, M.D., Ph.D., Melvin (1988). The Paleolithic Prescription: A Program of Diet and Exercise and a Design for Living. Harper and Row. p. 79. ISBN 978-0060916350.
  40. 1 2 3 Gibbons, Ann (September 2014). "The Evolution of Diet". National Geographic. Retrieved 4 September 2014.
  41. ↑ "For Evolving Brains, a 'Paleo' Diet Full of Carbs". The New York Times. 13 August 2015. Retrieved 14 August 2015.
  42. ↑ Hardy, Karen; Brand-Miller, Jennie; Brown, Katherine D.; Thomas, Mark G.; Copeland, Les (September 2015). "The Importance of Dietary Carbohydrate in Human Evolution". The Quarterly Review of Biology. 90 (3): 251–268. doi:10.1086/682587. JSTOR 682587. PMID 26591850.

Further reading

  • Bijlefeld M, Zoumbaris SK (2014). "Paleo Diet". Encyclopedia of Diet Fads: Understanding Science and Society (2nd ed.). ABC-CLIO. pp. 164–166. ISBN 978-1-61069-760-6.
  • Gorski D (18 March 2013). "It's a part of my paleo fantasy, it's a part of my paleo dream". Science-Based Medicine. Retrieved 1 February 2015.
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