ThePaleolithic diet,Paleo diet,caveman diet, orStone Age diet is a modernfad diet its proponents regard as consisting of foods reflecting what humans ate during thePaleolithic era.[1]
The diet avoidsfood processing and typically includesvegetables,fruits,nuts,roots, andmeat and excludesdairy products,grains,sugar,legumes, processedoils,salt,alcohol, andcoffee.[2] Historians can trace the ideas behind the diet to "primitive" diets advocated in the 19th century. In the 1970s,Walter L. Voegtlin popularized a meat-centric "Stone Age" diet; in the 21st century, the best-selling books ofLoren Cordain popularized the "Paleo diet".[3] As of 2019[update] the Paleolithic diet industry was worth approximatelyUS$500 million.[4]
In the 21st century, the sequencing of thehuman genome andDNA analysis of the remains ofanatomically modern humans have found evidence thathumans evolved rapidly in response to changing diet. This evidence undermines a core premise of the Paleolithic diet—that human digestion has remained essentially unchanged over time.[5]Paleoanthropological evidence has indicated that prehistoric humans ate plant-heavy diets that regularly included grains and other starchy vegetables, in contrast to the claims made by proponents of the Paleolithic diet.[6][7][8][9][10]
Advocates promote the Paleolithic diet as a way of improvinghealth.[11] There is some evidence that following it may lead to improvements in body composition and metabolism compared with the typicalWestern diet[12] or compared with diets recommended by some European nutritional guidelines.[13] On the other hand, following the diet can lead tonutritional deficiencies, such as an inadequatecalcium intake, and side effects can includeweakness,diarrhea, andheadaches.[14]
Adrienne Rose Johnson writes that the idea that the primitive diet was superior to current dietary habits dates back to the 1890s with such writers asEmmet Densmore andJohn Harvey Kellogg, the founder of the eponymous breakfast cereal company. Densmore proclaimed that "bread is the staff of death", while Kellogg supported a diet of starchy and grain-based foods in accord with "the ways and likings of our primitive ancestors".[15]Arnold DeVries advocated an early version of the Paleolithic diet in his 1952 book,Primitive Man and His Food.[16] In 1958,Richard Mackarness authoredEat Fat and Grow Slim, which proposed a low-carbohydrate "Stone Age" diet.[17]
In his 1975 bookThe Stone Age Diet, gastroenterologistWalter L. Voegtlin advocated a meat-based diet, with low proportions of vegetables and starchy foods, based on his declaration that humans were "exclusively flesh-eaters" until 10,000 years ago.[18]
In 1985Stanley Boyd Eaton andMelvin Konner published a controversial article in theNew England Journal of Medicine proposing that modern humans were biologically very similar to their primitive ancestors and so "genetically programmed" to consume pre-agricultural foods. Eaton and Konner proposed a "discordance hypothesis" by which the mismatch between modern diet and human biology gave rise to lifestyle diseases, such asobesity anddiabetes.[19]
The diet started to become popular in the 21st century, where it attracted a largely internet-based following using web sites, forums and social media.[20]
This diet's ideas were further popularized byLoren Cordain, a health scientist with a Ph.D. in physical education, who trademarked the words "The Paleo Diet" and who wrote a 2002 book of that title.[21]
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;[22] in 2013 and 2014 the Paleolithic diet wasGoogle's most searched weight-loss method.[23]
ThePaleolithic orPaleo diet is also sometimes referred to as thecaveman orStone Age diet.[24]
The basis of the diet is a re-imagining of what Paleolithic people ate, and different proponents recommend different diet compositions. Eaton and Konner, for example, wrote a 1988 bookThe Paleolithic Prescription withMarjorie Shostak, and it described a diet that is 65% plant based. This is not typical of more recently devised paleo diets; Loren Cordain's – probably the most popular – instead emphasizes animal products and avoidance ofprocessed food.[25] Diet advocates concede the modern Paleolithic diet cannot be a faithful recreation of what Paleolithic people ate, and instead aim to "translate" that into a modern context, avoiding such likely historical practices ascannibalism.[26]
Foodstuffs that have been described as permissible include:
The diet forbids the consumption of alldairy products. This is because milking did not exist until animals were domesticated after the Paleolithic era.[30]
Adopting the Paleolithic diet assumes that modern humans can reproduce the hunter-gatherer diet. Molecular biologistMarion 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."[31] Ideas aboutPaleolithic diet and nutrition are at best hypothetical.[32]
The data for Cordain's book came from six contemporary hunter-gatherer groups, mainly living in marginal habitats. One of the studies was on the!Kung, whose diet was recorded for a single month, and one was on thediet of the Inuit.[33] Due to these limitations, the book has been criticized as painting an incomplete picture of the diets of Paleolithic humans.[34] It has been noted that the rationale for the diet does not adequately account for the fact that, due to the pressures ofartificial 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, wildalmonds produce potentially fatal levels ofcyanide, but this trait has been bred out of domesticated varieties using artificial selection. Many vegetables, such asbroccoli, did not exist in the Paleolithic period; broccoli,cabbage,cauliflower, andkale are moderncultivars of the ancient speciesBrassica oleracea.[35]
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 theGwi people of southern Africa to 99% for the AlaskanNunamiut. Descendants of populations with different diets have different genetic adaptations to those diets, such as the ability to digest sugars from starchy foods. 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.[36]
A 2018 review of the diet of hunter-gatherer populations found that the dietary provisions of the Paleolithic diet had been based on questionable research, and were "difficult to reconcile with more detailed ethnographic and nutritional studies of hunter-gatherer diet".[37]
Researchers have proposed that cooked starches met the energy demands of an increasing brain size, based on variations in the copy number of genes encodingamylase.[38]
The methodological quality of research into the Paleolithic diet has been described as "poor to moderate."[39] Some of the paleo diet's proponents have made exaggerated health claims, such as the claim that the diet can reversediabetes and cureautoimmune diseases,[40] miring the diet in controversy.
Following the Paleolithic diet results in the consumption of fewer processed foods, less sugar, and less salt. Reduced consumption of such is consistent with mainstream advice about diet.[41] Diets reflecting a Paleolithic pattern of nutrition also share some similarities with traditional ethnic diets, such as theMediterranean diet, which has been found to result in more health benefits than theWestern diet.[42] Following the paleolithic diet can lead tonutritional deficiencies, such as those of vitamin D and calcium, which can in turn lead to compromised bone health.[43] The increased fish consumption suggested by the diet can also lead to an elevated risk of exposure to toxins.[44]
There is some evidence that the diet can help in achievingweight loss, due to the increasedsatiety from the foods typically eaten.[45] One trial ofobese postmenopausal women found improvements in weight and fat loss after six months, but the benefits had ceased by 24 months. Side effects among these participants included "weakness, diarrhea, and headaches." As with any other diet regime, the Paleolithic diet leads to weight loss because of overall decreasedcaloric intake, rather than any specific feature of the diet itself.[46]
There is no good evidence that following a Paleolithic diet reduces the risk ofcardiovascular disease ormetabolic syndrome,[47] nor is there any evidence that the Paleolithic diet is effective in treatinginflammatory bowel disease.[48]
The Paleolithic diet is similar to theAtkins diet, in that it encourages the consumption of large amounts ofred meat, especially meats high insaturated fat. Increased consumption of red meat can lead to a higher incidence of cardiovascular disease.[49]
The stated rationale for the Paleolithic diet is that human genes today are not different from human genes of 10,000 years ago, and that the diet of that time is therefore the best fit with humans today.[50] Loren Cordain has described the paleo diet as "the one and only diet that ideally fits our genetic makeup."[51]
The argument is that modern humans have not been able to biologically adapt to contemporary circumstances.[52] According to Cordain, before the agricultural revolution, hunter-gatherer diets rarely included grains, and obtaining milk from wild animals would have been "nearly impossible."[53] Advocates of the diet argue that the increase indiseases of affluence after the dawn of agriculture was caused by these changes in diet. Others, however, 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.[54]
According to the model from the evolutionary discordance hypothesis, "manychronic diseases anddegenerative conditions evident in modernWestern populations have arisen because of a mismatch betweenStone Age genes and modern lifestyles."[55] 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.[56] Studies of a variety of populations around the world show that humans can live healthily with a wide variety of diets and that humans have evolved to be flexible eaters.[57] Lactase persistence, which conferslactose tolerance into adulthood, 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 theNeolithic Revolution may have had some adverse effects on modern humans, if humans had not been nutritionally adaptable, these technological developments would have been dropped.[58]
Since the publication of Eaton and Konner's paper in 1985, analysis of theDNA of primitive human remains has provided evidence that evolving humans were continually adapting to new diets, thus challenging the hypothesis underlying the Paleolithic diet.[59] Evolutionary biologistMarlene 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. On this basis Zuk dismisses Cordain's claim that the paleo diet is "the one and only diet that fits our genetic makeup."[60]
PaleoanthropologistPeter Ungar has written that the paleo diet is a "myth," on account both of its invocation of a single suitable diet when in reality humans have always been a "work in progress," and because diet has always been varied because humans were spread widely over the planet.[61]
Anthropological geneticistAnne C. Stone has said that humans have adapted in the last 10,000 years in response to radical changes in diet. In 2016, she was quoted as saying "It drives me crazy when Paleo-diet people say that we've stopped evolving—we haven't."[62]
Melvin Konner has said the challenge to the hypothesis is not greatly significant since the real challenges to human non-adaptation have occurred with the rise of ever-more refined foodstuffs in the last 300 years.[63]
A 2019 analysis of diets in the United States ranked consumption of a Paleolithic diet as more environmentally harmful than consumption of an omnivorous diet, though not so harmful as aketogenic diet.[64]
Elizabeth Kolbert has written the Paleolithic diet's emphasis on meat consumption is a "disaster" on account of meat's comparatively high energy production costs.[65]
A lifestyle and ideology have developed around the diet.[66] "Paleolithic" products include clothing,smartphone apps, and cookware. Many Paleolithic cookery books have been bestsellers.[67]
As of 2019[update] the market for products with the word "Paleo" in their name was worth approximately $US500 million, with strong growth prospects despite pushback from the scientific community. Some products were taking advantage of the trend by touting themselves as "paleo-approved" despite having no apparent link to the movement's tenets.[68]
Like manyother diets, some proponents promote the Paleolithic diet by anappeal to nature and a narrative ofconspiracy theories about how nutritional research, which does not support the supposed benefits of the paleolithic diet, is controlled by a malignfood industry.[69] Paleolithic diet advocate John Durant has blamed suppression of the truth about diet in the United States on "the vegetarian lobby."[70]
Food portalEven 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.
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