User:QuackGuru/Sanx2

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12:25, 2 July 2018

• Paleolithic diet.

The Paleolithic diet (also called the Paleo diet, caveman diet or stone-age diet^[1]) is based mainly on foods presumed to have been available to Paleolithic humans.^[2] The ideas behind the diet can be traced to Walter Voegtlin,^[3]: 41 and were popularized in the best-selling books of Loren Cordain.^[4] The Paleo diet has become popular worldwide due to its purported health benefits.^[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^[2] 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 modern processed foods, but rather the foods that humans began eating after the Neolithic Revolution when humans transitioned from hunter-gatherer lifestyles to settled agriculture.^[2] It is essentially absent of high–glycemic index foods.^[5]

Like other fad diets, the Paleo diet is promoted as a way of improving health.^[7] Limited data exist on the metabolic effects on humans eating the diet.^[6] The evidence indicates following this diet may lead to improvements in terms of body composition and metabolic effects compared with the typical Western diet.^[6] This diet led to increased short-term benefits in the treating metabolic syndrome compared to national nutritional guideline diets.^[5] The diet seems to have considerable short-term improvements in weight loss but it may not be practical for some people due to the unclear long-term benefits.^[8] It can lead to an inadequate calcium intake^[2] though this diet may contribute to a beneficial calcium homeostasis due to its low salt and alkalizing properties.^[5] Side effects can include weakness, diarrhea, and headaches.^[8]

The digestive abilities of anatomically modern humans, however, are different from those of Paleolithic humans, which undermines the diet's core premise.^[9] Neanderthals and early modern humans consumed a similarly more complex diet than previously indicated and worldwide spread of human population meant that humans were, by necessity, nutritionally adaptable; in contrast, several authors have indicated that major behavioral changes, such as a wider diet, happened among modern human groups.^[10]

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.^[11] 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,^[3]: 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.^[4] 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] The Paleo diet has become popular worldwide due to its purported health benefits.^[5]

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.^[7][16] A Paleo lifestyle and ideology have developed around the diet.^[17][18]

The diet advises eating only foods presumed to be available to Paleolithic humans, but there is wide variability in the way this practice is interpreted and applied^[6] and an ongoing debate over the specific foods eaten by our ancestors.^[2]

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.^[2] It is low in objectionable carbohydrates such as starches, high in fiber, and is low glycemic.^[6]

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

• "Vegetables, fruits, nuts, roots, meat, and organ meats";^[2]
• "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)";^[5] and
• "avoids processed foods, and emphasizes eating vegetables, fruits, nuts and seeds, eggs, and lean meats".^[6]

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] The Paleo diet's focus on protein from lean meat may make people feel full.^[6] It is hypothesized that the Paleo diet could be a useful alternative to the unhealthy Western diet.^[2] The evidence indicates following this diet may lead to improvements in terms of body composition and metabolic effects compared with the typical Western diet.^[6] Following the Paleo diet can lead to nutritional deficiencies such as vitamin D and calcium which in turn could lead to compromised bone health.^[1] Evaluation of vitamin D levels may be necessary for people following the Paleo diet.^[20] The diet may help with calcium balance due to its low salt and alkalizing properties,^[5] though it is recommended to take enough calcium when following the Paleo diet.^[21] A 2014 study found that while calcium intake was less following diet, it resulted in greater magnesium intake, and the reduced calcium intake was offset for by reduced calcium and magnesium excretions.^[5] They suspected that "calcium homeostasis was unlikely to have become compromised."^[5] There is also an increased risk of ingesting toxins from high fish consumption.^[2]

Limited data exists on the metabolic effects on humans eating a Paleo diet.^[6] Positive conclusions about the effectiveness of the Paleo diet should be considered with caution due to lack of variety and duration of a small number of studies.^[21] 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, and it may lower the risk of aging-associated diseases.^[2] There is moderate evidence for better short-term improvements than the various guideline-based diets that were used as controls in the trials for the effects of paleolithic nutrition on metabolic syndrome, though the evidence is not strong enough to recommend the Paleo diet for treatment of metabolic syndrome.^[5] The preliminary evidence suggests the Paleo diet may be useful in managing various metabolic disorders.^[21] The Paleo diet was more fulfilling than a diabetic diet for people with type 2 diabetes and it was seen favorable for weight loss, but there were difficulties in following the diet.^[2] As of 2014 there was no credible evidence the Paleo diet is effective in treating inflammatory bowel disease.^[20]

Research into the weight loss effects of the Paleolithic diet has generally been of poor quality.^[8] A 2014 trial of obese postmenopausal women found considerable 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".^[8] The 2017 review found "The paleo diet appears to have significant short-term improvements in weight loss and other metabolic factors, but cost, time commitment, side effects, and unclear long-term benefits may make this diet impractical for some individuals."^[8]

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.

Close to thirty years after the evolutionary discordance hypothesis was proposed, global obesity, heart disease, and type 2 diabetes rates continue to soar; these developments do not indicate that this hypothesis is wrong, but rather insufficient to depend mainly on genetic awareness of human diet and the belief of the Paleolithic era as the human evolutionary benchmark.^[27] Further, 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.^[9]: 114 On this basis Zuk dismisses Cordain's claim that the Paleo diet is "the one and only diet that fits our genetic makeup".^[9]

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]

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]

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]

• Inuit diet
• Leaky gut syndrome
• Staffan Lindeberg, researcher
• Low carbohydrate diet
• Low-glycemic diet
• Modern primitive
• Nutritional genomics
• Paleolithic lifestyle
• Raw foodism