Paleolithic diet From Wikipedia, the free encyclopedia
This article is about a modern nutritional approach. For information on the dietary practices of Paleolithic humans, see Paleolithic#Diet and nutrition.
[hide]This article has multiple issues. Please help improve it or discuss these issues on the talk page. This article's factual accuracy is disputed. (April 2013) The neutrality of this article is disputed. (June 2014) This article possibly contains original research. (June 2014) This article needs more medical references for verification or relies too heavily on primary sources. (June 2014)
Fruits and vegetables, rich in vitamins, potassium and fiber, represent an important feature of forager diets.
The Paleolithic diet, also popularly referred to as the caveman diet, Stone Age diet and hunter-gatherer diet, is a modern nutritional diet designed to emulate, insofar as possible using modern foods, the diet of wild plants and animals eaten by humans during the Paleolithic era.[1] Proponents of the diet therefore recommend avoiding any foods that are thought not to have been available to humans at that time, including dairy products, grains, legumes, processed oils, and refined sugar. The Paleolithic diet is a fad diet[2] that became popular in the late 2000s.
The diet is based on several premises. Proponents of the diet posit that during the Paleolithic era — a period lasting around 2.5 million years that ended about 10,000 years ago with the advent of agriculture and domestication of animals — humans evolved nutritional needs specific to the foods available at that time, and that the nutritional needs of modern humans remain best adapted to the diet of their Paleolithic ancestors. Proponents also claim that human metabolism has been unable to adapt fast enough to handle many of the foods that have become available since the advent of agriculture. Thus, modern humans are said to be maladapted to eating foods such as grain, legumes, and dairy, and in particular the high-calorie processed foods that are a staple part of most modern diets. Proponents claim that it is modern humans' inability to digest properly these comparatively new types of food that has led to modern-day problems such as obesity, heart disease, and diabetes. Conversely, it is claimed that followers of the Paleolithic diet may enjoy a longer, healthier, more active life.
Critics of the Paleolithic diet have pointed out a number of flaws with its underlying logic, including the fact that humans are much more nutritionally flexible than previously thought, that the hypothesis that Paleolithic humans were genetically adapted to specific local diets remains to be proven, that the Palaeolithic period was extremely long and saw a variety of forms of human settlement and subsistence in a wide variety of changing nutritional landscapes, and that currently very little is known for certain about what Palaeolithic humans ate. Nutritionists have stated that the diet may be less effective than other popular diets in promoting good health.
Contents
History An early book on the topic was The Stone Age Diet, self-published in 1975 by Walter Voegtlin.[3] In 1985, Boyd Eaton and Melvin Konner published a paper[4] on Paleolithic nutrition in the New England Journal of Medicine followed in 1988 by the book, with Marjorie Shostak, The Paleolithic Prescription. Since the late 1990s many others have published books and articles promoting the diet, including Staffan Lindeberg, Mark Sisson, and Arthur De Vany.
The diet was overshadowed by regimens such as the Atkins diet and South Beach Diet until the publication of a popular book by Loren Cordain. Cordain holds a bachelor degree in health science, a masters and doctoral degree in exercise physiology, and has studied nutrition professionally for over twenty years. His Web site styles him as "Dr Loren Cordain, world's leading expert on paleolithic diets and founder of The Paleo Movement".[5] He is the owner of the trademark "The Paleo Diet".[6] The paleolithic diet has grown greatly in popularity since the publication of Cordain's book, and in 2013 was Google’s most searched-for weight loss method.[7]
Rationale for the diet
The neutrality of this section is disputed. Relevant discussion may be found on the talk page. Please do not remove this message until the dispute is resolved. (June 2014)
Paleolithic carving of a mammoth. Hunting by humans may have been a factor in its extinction, causing resource scarcity which may in turn have contributed to the development of agriculture.
The rationale for the Paleolithic diet derives from a popular tenet in evolutionary medicine known as the evolutionary discordance hypothesis,[8] a hypothesis first articulated by Eaton and Konner in their 1985 article "Paleolithic Nutrition: A Consideration of Its Nature and Current Implications".[9] The evolutionary discordance hypothesis states that "many chronic diseases and degenerative conditions evident in modern Western populations have arisen because of a mismatch between Stone Age genes and recently adopted lifestyles."[10] The hypothesis takes a specific form with regard to diet and nutrition, and, in this form, includes the following claims and arguments:
It has been noted that the rationale for the diet does not take adequate account of the fact that, due to the pressures of artificial selection, most modern domesticated plants and animals differ drastically from their Paeleolithic ancestors, whose nutritional profiles often differed drastically from their modern counterparts. For example, wild almonds produce potentially fatal levels of cyanide, but this harmful poison has been bred out of domesticated varieties by artificial selection. Moreover, many vegetables like Broccoli "did not ... exist in the Paleolithic period".[23] Broccoli and many other genetically similar vegetables (like cabbage, cauliflower, kale, etc.) are in fact modern cultivars of the ancient species Brassica oleracea, a wild plant also known as wild mustard.
It is often argued that preagricultural foragers did not suffer from the diseases of affluence simply because they did not live long enough to develop them.[24]
With regard to attempts to emulate the "ideal" 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 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".[25] Ideas about Paleolithic diet and nutrition are at best hypothetical.[26][27]
Trying to devise an ideal diet by studying contemporary hunter-gatherers is difficult because of the great disparities that exist, for example with the animal-derived calorie percentage ranging from 25% in the Gwi people of southern Africa to 99% in Alaskan Nunamiut.[28]
Food energy excess, relative to energy expended, rather than the consumption of specific foods may underlie the diseases of affluence. Studies of traditionally living populations show that humans can live healthily with a wide variety of diets. We have evolved to be flexible eaters. "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 we consume and the energy we spend."[29]
The diet
Seeds such as walnuts are rich sources of protein and micronutrients
More protein Meat, seafood, and other animal products represent the staple foods of modern-day Paleo diets, since advocates claim protein comprises 19-35% of the calories in hunter-gatherer diets.[30] The Centers for Disease Control and Prevention, the national public health institute of the United States, recommends that 10-35% of calories come from protein.[31]
Fewer carbohydrates The diet recommends the consumption of non-starchy fresh fruits and vegetables to provide 35-45 % daily calories and be the main source of carbohydrates.[30] According to the United States Department of Agriculture,[32] the acceptable macronutrient distribution range for carbohydrates is 45 to 65 percent of total calories. A typical modern diet gets a lot of carbohydrates from dairy products and grains, but these are excluded in the Paleolithic diet.
High fiber High fiber intake not via grains, but via non-starchy vegetables and fruits.[30]
More fat Advocates recommend, relative to modern diets, that the Paleolithic diet have moderate to higher fat intake dominated by monounsaturated and polyunsaturated fats and omega-3 fats, but avoiding trans fats, and omega-6 fats.
Less salt It is well known that modern diets are high in salt[33] and many diets, including the Paleolithic, recommend a reduction.
Balanced alkaline vs. acid Any food presents either a net acid (e.g. meats, fish, grains, legumes, cheese, and salt) or alkaline (e.g. fruits and vegetables) load to the kidneys.[30]
More micronutrients A higher intake of vitamins and minerals is recommended via grass-fed meats, fruits, and vegetables rather than grains.[30]
Energy density The Paleolithic diet has lower energy density than the typical diet consumed by modern humans.[34] This is especially true in primarily plant-based/vegetarian versions of the diet, but it still holds if substantial amounts of meat are included. For example, most fruits and berries contain 0.4–0.8 calories per gram, and vegetables can be even lower than that (cucumbers contain only 0.16 calories per gram).[35] Game meat, such as cooked wild rabbit, is more energy-dense (up to 1.7 calories per gram), but it does not constitute the bulk of the diet by mass or volume at the recommended plant/animal ratios, and it does not reach the caloric densities of many processed foods commonly consumed by modern humans.
Consuming foods low in energy density (kcal/g) decreases energy intake over several days, but the effectiveness of this strategy for weight loss has not been tested.[36]
Even some authors who may appear otherwise critical of the Paleolithic diet have argued that the high energy density of modern diets, as compared to ancestral or primate diets, contributes to the incidence of diseases of affluence in the industrial world.[37]
Micronutrient density
Fish and seafood, such as salmon, are significant sources of essential micronutrients
Fish and seafood represent a particularly rich source of omega-3 fatty acids and other micronutrients, such as iodine, iron, zinc, copper, and selenium, that are crucial for proper brain function and development.[38] Terrestrial animal foods, such as muscle, brain, bone marrow, thyroid gland, and other organs, also represent a primary source of these nutrients. Calcium-poor grains and legumes are excluded from the diet. However, leafy greens like kale and dandelion greens, as well as nuts like almonds, are very high sources of calcium.[39] Two notable exceptions are calcium and vitamin D, both of which may be present in the diet in inadequate quantities. Modern humans require much more vitamin D than foragers, because they do not get the same amount of exposure to sun. This need is commonly satisfied in developed countries by artificially fortifying dairy products with the vitamin. To avoid deficiency, a modern human on a forager diet would have to take artificial supplements of the vitamin, ensure adequate intake of some fatty fish,[40] or increase the amount of exposure to sunlight (it has been estimated that 30 minutes of exposure to midday sun twice a week is adequate for most people).[41][original research?]
Eating a wide variety of plant foods is recommended to avoid high intakes of potentially harmful bioactive substances, such as goitrogens, which are present in some roots, seeds, and vegetables.
Beverages On the Paleolithic diet, practitioners are permitted to drink mainly water, and some advocates recommend tea as a healthy drink. Neither alcohol[42] nor coffee is considered "paleo" as our ancestors could not produce these drinks.
Raw vs. cooked Unlike raw food diets, all foods may be cooked, without restrictions.[43] However, there are Paleolithic dieters who believe that humans have not adapted to cooked foods since the first control of fire by Homo erectus, and so they eat only foods that are both raw and Paleolithic.[44]
Exclusions Food groups that advocates claim were rarely or never consumed by humans before the Neolithic agricultural revolution are excluded from the diet, mainly dairy products, grains, legumes (e.g., beans and peanuts), processed oils, refined sugar, and salt. Many of these foods would have been available at certain times of the year and may or may not have been consumed. Cereal grains, legumes, and milk contain bioactive substances, such as gluten and casein, that have been implicated in the development of various health problems. Consumption of gluten, a component of certain grains, such as wheat, rye, and barley, is known to have adverse health effects in individuals suffering from a range of gluten sensitivities, including celiac disease. Since the Paleolithic diet is devoid of cereal grains, it is free of gluten. The paleo diet is also casein-free. Casein, a protein found in milk and dairy products, may impair glucose tolerance in humans.
Compared to Paleolithic food groups, cereal grains and legumes contain high amounts of antinutrients, including alkylresorcinols, alpha-amylase inhibitors, protease inhibitors, lectins, and phytates, substances known to interfere with the body's absorption of many key nutrients. Molecular-mimicking proteins, which are basically made up of strings of amino acids that closely resemble those of another totally different protein, are also found in grains and legumes, as well as milk and dairy products. Advocates of the Paleolithic diet have argued that these components of agrarian diets promote vitamin and mineral deficiencies and may explain the development of the diseases of civilization as well as a number of autoimmune-related diseases.
Reception Nutritionists agree that the Paleolithic diet is beneficial in that it cuts processed foods that have been highly modified from their raw state such as white bread, artificial cheese, certain cold cuts and packaged meats, potato chips, and sugary cereals. These often offer less nutrients than their unprocessed equivalents, and may be packed with calories, sodium and preservatives that may increase the risk of heart disease and certain cancers.[45]
A ranking by U.S. News & World Report, involving a panel of experts, evaluated based on factors including health, weight loss, and ease of following. In 2014, it tied for last place out of 32 with the Dukan Diet.[46]
Evidence for the effect of the switch to agriculture on general life expectancy is mixed, with some populations exhibiting an apparent decrease in life expectancy and others an apparent increase.[47] And according to S. Jay Olshansky and Bruce Carnes, "there is neither convincing evidence nor scientific logic to support the claim that adherence to a Paleolithic diet provides a longevity benefit."[48]
According to the British Dietetic Association the diet excludes key food groups, raising the potential for nutrition
This article is about a modern nutritional approach. For information on the dietary practices of Paleolithic humans, see Paleolithic#Diet and nutrition.
[hide]This article has multiple issues. Please help improve it or discuss these issues on the talk page. This article's factual accuracy is disputed. (April 2013) The neutrality of this article is disputed. (June 2014) This article possibly contains original research. (June 2014) This article needs more medical references for verification or relies too heavily on primary sources. (June 2014)
Fruits and vegetables, rich in vitamins, potassium and fiber, represent an important feature of forager diets.
The Paleolithic diet, also popularly referred to as the caveman diet, Stone Age diet and hunter-gatherer diet, is a modern nutritional diet designed to emulate, insofar as possible using modern foods, the diet of wild plants and animals eaten by humans during the Paleolithic era.[1] Proponents of the diet therefore recommend avoiding any foods that are thought not to have been available to humans at that time, including dairy products, grains, legumes, processed oils, and refined sugar. The Paleolithic diet is a fad diet[2] that became popular in the late 2000s.
The diet is based on several premises. Proponents of the diet posit that during the Paleolithic era — a period lasting around 2.5 million years that ended about 10,000 years ago with the advent of agriculture and domestication of animals — humans evolved nutritional needs specific to the foods available at that time, and that the nutritional needs of modern humans remain best adapted to the diet of their Paleolithic ancestors. Proponents also claim that human metabolism has been unable to adapt fast enough to handle many of the foods that have become available since the advent of agriculture. Thus, modern humans are said to be maladapted to eating foods such as grain, legumes, and dairy, and in particular the high-calorie processed foods that are a staple part of most modern diets. Proponents claim that it is modern humans' inability to digest properly these comparatively new types of food that has led to modern-day problems such as obesity, heart disease, and diabetes. Conversely, it is claimed that followers of the Paleolithic diet may enjoy a longer, healthier, more active life.
Critics of the Paleolithic diet have pointed out a number of flaws with its underlying logic, including the fact that humans are much more nutritionally flexible than previously thought, that the hypothesis that Paleolithic humans were genetically adapted to specific local diets remains to be proven, that the Palaeolithic period was extremely long and saw a variety of forms of human settlement and subsistence in a wide variety of changing nutritional landscapes, and that currently very little is known for certain about what Palaeolithic humans ate. Nutritionists have stated that the diet may be less effective than other popular diets in promoting good health.
Contents
History An early book on the topic was The Stone Age Diet, self-published in 1975 by Walter Voegtlin.[3] In 1985, Boyd Eaton and Melvin Konner published a paper[4] on Paleolithic nutrition in the New England Journal of Medicine followed in 1988 by the book, with Marjorie Shostak, The Paleolithic Prescription. Since the late 1990s many others have published books and articles promoting the diet, including Staffan Lindeberg, Mark Sisson, and Arthur De Vany.
The diet was overshadowed by regimens such as the Atkins diet and South Beach Diet until the publication of a popular book by Loren Cordain. Cordain holds a bachelor degree in health science, a masters and doctoral degree in exercise physiology, and has studied nutrition professionally for over twenty years. His Web site styles him as "Dr Loren Cordain, world's leading expert on paleolithic diets and founder of The Paleo Movement".[5] He is the owner of the trademark "The Paleo Diet".[6] The paleolithic diet has grown greatly in popularity since the publication of Cordain's book, and in 2013 was Google’s most searched-for weight loss method.[7]
Rationale for the diet
The neutrality of this section is disputed. Relevant discussion may be found on the talk page. Please do not remove this message until the dispute is resolved. (June 2014)
Paleolithic carving of a mammoth. Hunting by humans may have been a factor in its extinction, causing resource scarcity which may in turn have contributed to the development of agriculture.
The rationale for the Paleolithic diet derives from a popular tenet in evolutionary medicine known as the evolutionary discordance hypothesis,[8] a hypothesis first articulated by Eaton and Konner in their 1985 article "Paleolithic Nutrition: A Consideration of Its Nature and Current Implications".[9] The evolutionary discordance hypothesis states that "many chronic diseases and degenerative conditions evident in modern Western populations have arisen because of a mismatch between Stone Age genes and recently adopted lifestyles."[10] The hypothesis takes a specific form with regard to diet and nutrition, and, in this form, includes the following claims and arguments:
- Paleolithic humans were genetically adapted to eating specifically those foods that were readily available to them in their local environments (termed environments of evolutionary adaptedness, or EEAs, by researchers in the field of evolutionary medicine). These foods therefore shaped the nutritional needs of Paleolithic humans.[11][12] A necessary implication of this assumption is that Paleolithic humans were not adapted (maladapted) to eating foods other than those readily available to them.
- Eating those foods to which Paleolithic humans were specifically adapted conferred upon them relative health and longevity, and precluded the possibility (or at least lowered the risk) of their contracting diseases like obesity, atherosclerosis, pulmonary disease, type 2 diabetes, certain types of cancer, and dental cavities.[13][14][15] A necessary implication of this assumption is that eating foods to which Paleolithic humans were maladapted resulted in ill health and heightened rates of disease.
- Most Paleolithic communities were organized around some form of hunter-gatherer or forager-gather subsistence, which implies that they regularly ate wild plants and root vegetables, fruits and nuts, and the considerable quantities of the flesh of wild animals (including fish and shellfish). They did not eat (because they could not cultivate in large enough quantity) legumes, grains, salt, the milk of other animals, and large quantities of animal fat.[16]
- The physiology and metabolism of modern humans have changed little, if at all, since the time of their Paleolithic ancestors.[17][18]
- Because of (1) and (4), modern humans remain genetically adapted to the diet of their Paleolithic ancestors, and genetically maladapted to foods not eaten by their these ancestors.[18]
- The advent of agriculture and industrialization has led to the availability of foods to which humans are not genetically adapted, and these detrimental foods (particularly carbohydrate-rich starches like wheat and maize) have now largely replaced beneficial foods (like lean animal protein) in human diets.[16]
- Diseases of affluence and lifestyle diseases are modern afflictions that have arisen in part from the eating of foods to which humans are not genetically adapted.[14]
- It is currently possible to discover (through palaeontology, archaeology, and the study of modern hunter-gatherer societies) what the diet of Paleolithic humans consisted of and to reproduce or at least emulate it using foods readily available today.[19][20]
- Lean meat (should constitute about 45–65% of daily caloric intake)[22]
- Non-starchy vegetables
- Fruits and berries
- Nuts
- No refined sugar (except honey)
- Very little or no dairy food (butter, milk, cheese, yogurt).
- Very little cereal grains (maize, wheat, barely, rice, etc.).
- Very little salt.
It has been noted that the rationale for the diet does not take adequate account of the fact that, due to the pressures of artificial selection, most modern domesticated plants and animals differ drastically from their Paeleolithic ancestors, whose nutritional profiles often differed drastically from their modern counterparts. For example, wild almonds produce potentially fatal levels of cyanide, but this harmful poison has been bred out of domesticated varieties by artificial selection. Moreover, many vegetables like Broccoli "did not ... exist in the Paleolithic period".[23] Broccoli and many other genetically similar vegetables (like cabbage, cauliflower, kale, etc.) are in fact modern cultivars of the ancient species Brassica oleracea, a wild plant also known as wild mustard.
It is often argued that preagricultural foragers did not suffer from the diseases of affluence simply because they did not live long enough to develop them.[24]
With regard to attempts to emulate the "ideal" 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 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".[25] Ideas about Paleolithic diet and nutrition are at best hypothetical.[26][27]
Trying to devise an ideal diet by studying contemporary hunter-gatherers is difficult because of the great disparities that exist, for example with the animal-derived calorie percentage ranging from 25% in the Gwi people of southern Africa to 99% in Alaskan Nunamiut.[28]
Food energy excess, relative to energy expended, rather than the consumption of specific foods may underlie the diseases of affluence. Studies of traditionally living populations show that humans can live healthily with a wide variety of diets. We have evolved to be flexible eaters. "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 we consume and the energy we spend."[29]
The diet
Seeds such as walnuts are rich sources of protein and micronutrients
More protein Meat, seafood, and other animal products represent the staple foods of modern-day Paleo diets, since advocates claim protein comprises 19-35% of the calories in hunter-gatherer diets.[30] The Centers for Disease Control and Prevention, the national public health institute of the United States, recommends that 10-35% of calories come from protein.[31]
Fewer carbohydrates The diet recommends the consumption of non-starchy fresh fruits and vegetables to provide 35-45 % daily calories and be the main source of carbohydrates.[30] According to the United States Department of Agriculture,[32] the acceptable macronutrient distribution range for carbohydrates is 45 to 65 percent of total calories. A typical modern diet gets a lot of carbohydrates from dairy products and grains, but these are excluded in the Paleolithic diet.
High fiber High fiber intake not via grains, but via non-starchy vegetables and fruits.[30]
More fat Advocates recommend, relative to modern diets, that the Paleolithic diet have moderate to higher fat intake dominated by monounsaturated and polyunsaturated fats and omega-3 fats, but avoiding trans fats, and omega-6 fats.
Less salt It is well known that modern diets are high in salt[33] and many diets, including the Paleolithic, recommend a reduction.
Balanced alkaline vs. acid Any food presents either a net acid (e.g. meats, fish, grains, legumes, cheese, and salt) or alkaline (e.g. fruits and vegetables) load to the kidneys.[30]
More micronutrients A higher intake of vitamins and minerals is recommended via grass-fed meats, fruits, and vegetables rather than grains.[30]
Energy density The Paleolithic diet has lower energy density than the typical diet consumed by modern humans.[34] This is especially true in primarily plant-based/vegetarian versions of the diet, but it still holds if substantial amounts of meat are included. For example, most fruits and berries contain 0.4–0.8 calories per gram, and vegetables can be even lower than that (cucumbers contain only 0.16 calories per gram).[35] Game meat, such as cooked wild rabbit, is more energy-dense (up to 1.7 calories per gram), but it does not constitute the bulk of the diet by mass or volume at the recommended plant/animal ratios, and it does not reach the caloric densities of many processed foods commonly consumed by modern humans.
Consuming foods low in energy density (kcal/g) decreases energy intake over several days, but the effectiveness of this strategy for weight loss has not been tested.[36]
Even some authors who may appear otherwise critical of the Paleolithic diet have argued that the high energy density of modern diets, as compared to ancestral or primate diets, contributes to the incidence of diseases of affluence in the industrial world.[37]
Micronutrient density
Fish and seafood, such as salmon, are significant sources of essential micronutrients
Fish and seafood represent a particularly rich source of omega-3 fatty acids and other micronutrients, such as iodine, iron, zinc, copper, and selenium, that are crucial for proper brain function and development.[38] Terrestrial animal foods, such as muscle, brain, bone marrow, thyroid gland, and other organs, also represent a primary source of these nutrients. Calcium-poor grains and legumes are excluded from the diet. However, leafy greens like kale and dandelion greens, as well as nuts like almonds, are very high sources of calcium.[39] Two notable exceptions are calcium and vitamin D, both of which may be present in the diet in inadequate quantities. Modern humans require much more vitamin D than foragers, because they do not get the same amount of exposure to sun. This need is commonly satisfied in developed countries by artificially fortifying dairy products with the vitamin. To avoid deficiency, a modern human on a forager diet would have to take artificial supplements of the vitamin, ensure adequate intake of some fatty fish,[40] or increase the amount of exposure to sunlight (it has been estimated that 30 minutes of exposure to midday sun twice a week is adequate for most people).[41][original research?]
Eating a wide variety of plant foods is recommended to avoid high intakes of potentially harmful bioactive substances, such as goitrogens, which are present in some roots, seeds, and vegetables.
Beverages On the Paleolithic diet, practitioners are permitted to drink mainly water, and some advocates recommend tea as a healthy drink. Neither alcohol[42] nor coffee is considered "paleo" as our ancestors could not produce these drinks.
Raw vs. cooked Unlike raw food diets, all foods may be cooked, without restrictions.[43] However, there are Paleolithic dieters who believe that humans have not adapted to cooked foods since the first control of fire by Homo erectus, and so they eat only foods that are both raw and Paleolithic.[44]
Exclusions Food groups that advocates claim were rarely or never consumed by humans before the Neolithic agricultural revolution are excluded from the diet, mainly dairy products, grains, legumes (e.g., beans and peanuts), processed oils, refined sugar, and salt. Many of these foods would have been available at certain times of the year and may or may not have been consumed. Cereal grains, legumes, and milk contain bioactive substances, such as gluten and casein, that have been implicated in the development of various health problems. Consumption of gluten, a component of certain grains, such as wheat, rye, and barley, is known to have adverse health effects in individuals suffering from a range of gluten sensitivities, including celiac disease. Since the Paleolithic diet is devoid of cereal grains, it is free of gluten. The paleo diet is also casein-free. Casein, a protein found in milk and dairy products, may impair glucose tolerance in humans.
Compared to Paleolithic food groups, cereal grains and legumes contain high amounts of antinutrients, including alkylresorcinols, alpha-amylase inhibitors, protease inhibitors, lectins, and phytates, substances known to interfere with the body's absorption of many key nutrients. Molecular-mimicking proteins, which are basically made up of strings of amino acids that closely resemble those of another totally different protein, are also found in grains and legumes, as well as milk and dairy products. Advocates of the Paleolithic diet have argued that these components of agrarian diets promote vitamin and mineral deficiencies and may explain the development of the diseases of civilization as well as a number of autoimmune-related diseases.
Reception Nutritionists agree that the Paleolithic diet is beneficial in that it cuts processed foods that have been highly modified from their raw state such as white bread, artificial cheese, certain cold cuts and packaged meats, potato chips, and sugary cereals. These often offer less nutrients than their unprocessed equivalents, and may be packed with calories, sodium and preservatives that may increase the risk of heart disease and certain cancers.[45]
A ranking by U.S. News & World Report, involving a panel of experts, evaluated based on factors including health, weight loss, and ease of following. In 2014, it tied for last place out of 32 with the Dukan Diet.[46]
Evidence for the effect of the switch to agriculture on general life expectancy is mixed, with some populations exhibiting an apparent decrease in life expectancy and others an apparent increase.[47] And according to S. Jay Olshansky and Bruce Carnes, "there is neither convincing evidence nor scientific logic to support the claim that adherence to a Paleolithic diet provides a longevity benefit."[48]
According to the British Dietetic Association the diet excludes key food groups, raising the potential for nutrition