Paleolithic diet

The Paleolithic diet, also known as the caveman diet, paleodiet, Stone Age diet, the preagricultural diet, or hunter-gatherer diet, is the diet of wild plants and animals that various human species (see Homo (genus)) habitually consumed during the Paleolithic period (the Old Stone Age), a period of about 2 million years duration, ending about 10,000 years ago, when our species, Homo sapiens, invented agriculture. The designation also applies to contemporary diets that resemble that preagricultural human diet in the plant and animal sources of food recommended for consumption and avoidance, though usually from domesticated sources.

Those who advocate that contemporary humans should regularly consume a Paleolithic diet base their advocacy on the premise that natural selection had 2 million or more years to genetically adapt the metabolism and physiology of the various human species to such a diet, and that in the 10,000 years since the invention of agriculture and its consequent major change in the human diet, natural selection has had too little time to make the optimal genetic adaptations to the new diet. According to those advocates, physiological and metabolic maladaptations result from those suboptimal genetic adaptations, which in turn contribute to many of the so-called diseases of civilization.^[1]

Those considerations give rise to a simple theme for adhering to a Paleolithic-type diet in modern times: if a food item resembles one that can be found in the wild, obtained with bare hands or simple tools, and ingested immediately without cooking, processing, and by simple preparation (i.e., peeling, cracking, washing, etc.), and cause the consumer no ill effects either during or after consumption, then it can be considered edible, and therefore permissible to eat. Any food meeting this standard can then be cooked and prepared by the simplest means as practical and consumed in modest quantities. Food exclusions comprise those introduced in the human food supply late in the course of human evolution, in particular after the invention of agriculture about 10,000 years ago: cereal grains, legumes and dairy products.^[2]

Overview

Supporters of this theory argue that since human genetics have scarcely changed since the stone age, an ideal diet would be a reconstructed stone age diet such as the one humans and proto-humans used before the Neolithic Revolution. Therefore through studying archeology and modern hunter-gatherers it could be determined what a healthy diet would comprise. Interest in paleolithic nutrition has grown in recent years as low-carbohydrate diets have become more popular, as the two practices have, by coincidence not design, certain similarities.

This dietary concept is concerned primarily with health issues, as opposed to ethical or economic concerns. Advocates of the Paleolithic Diet believe that the best foods for the human body are those that humans are best adapted to eat. Proponents argue that many diseases are diet related and can be caused by straying from this approach.

History

History of the human diet

Contributions are needed for this section

History of this theory

One of the first suggestions that following a diet similar to that of the late Paleolithic area would improve a person's health was made in the New England Journal of Medicine in 1985^[3]. This was followed up by a book, The Paleolithic Prescription^[4], which focused on achieving the same proportions of nutrients (fat, protein, and carbohydrates, as well as vitamins and minerals) as were present in the diet of late Paleolithic people, not on excluding foods that were not available before the development of agriculture. As such, this early version of the paleolithic diet recommended such foods as skimmed milk, whole grain bread, brown rice, and potatoes prepared without fat, on the argument that such foods have the same nutritional properties as paleolithic foods.

More recent versions of the paleolithic diet, such as NeanderThin^[5] and The Paleo Diet^[6], focus on eliminating all foods that were not available to human beings in Paleolithic times, such as milk, dairy products, and grains.

Practices

One of the basic premises of this nutritional theory is that many of the foods that humans eat today are not suitable for consumption due to the extensive preparation and processing methods used in today's kitchens. These foods, if eaten in their natural state, are ill-tasting, unchewable, and sometimes toxic to the human body. Without modern processing methods, these foods are, in effect, inedible.

Foods in the diet

Foods which are included in the diet are ones that can be obtained by using paleolithic tools and practices, like meat (preferably game, though many followers of the diet eat farmed meat for practical reasons), fish, and gathered or foraged fruits, leaves, and roots of plants, mushrooms, nuts, eggs, and honey.

Some practitioners allow the use of oils derived from those foods which can be obtained and produced through paleolithic means and are edible in their natural, uncooked state. Examples could include sesame oil and safflower oil, but not olive oil or oils derived from beans (for example, peanut oil) or grains (for example, corn oil). Others avoid the use of any oil, as it is a processed food.

The non-animal foods available in the diet are the same as those available in raw veganism. However, there are two fundamental differences between raw veganism and the paleolithic diet: Firstly, practitioners consume meat and other animal products (in fact usually more is consumed than on a standard modern diet, in some cases substantially more). Secondly, any and all food may be cooked if desired.

Foods not in the diet

Vegetable foods which are not edible raw and unprocessed are excluded from the diet. The foods falling into this category are mainly grains (wheat, corn, rice, etc.), starchy vegetables (i.e., beans, and potatoes), certain fruits and nuts (e.g. olives and cashews), and refined sugars. Alcoholic beverages are generally excluded because fermentation is also a form of processing, although some paleolithic eaters allow certain exceptions (i.e., wine, since fermented (over-ripe) fruit can be found and consumed in small quantities with little ill effect). Dairy products are excluded despite being edible raw, since they cannot be found or consumed easily in nature, at least in any considerable quantity, and are consequently a post-agricultural food.

Intake

The generally prescribed proportions of protein, fat, and carbohydrate are approximately 20-35%, 30-60%, and 20-35% respectively by calories. By calories the diet is commonly around 45-65% animal products and 35-55% plant products. Alternatively, because of the large amount of water in fruits and vegetables, the diet is, by weight, roughly 2/3 plant products and 1/3 animal products.

Consequently, because of the high water content of fruits and vegetables, it is generally accepted that slightly less non-food water is required for optimal health. This is also supported by the fact that fresh water is not always readily available in the wild and that humans must rely on other sources for their water needs. This is not a reduction in need for water, but a shift in where water can be obtained.

The vitamin and mineral content of the diet is very high compared to a standard diet, in many cases a multiple of the RDA.

Food sources and preparation

For many practitioners of paleolithic nutrition, the foods' source is just as important as the kind of foods being consumed. It is common practice to obtain paleolithic foods from as natural a source as possible. Farmed meats, especially those organically farmed, are available from many natural sources, from free range poultry to grass fed beef, with many proponents preferring, thought not as practical, wild game meats like quail, rabbit, and venison.

It is common practice among paleolithic eaters that when cooking, unconventional cooking means should be avoided, such as the use of microwave ovens, and that foods are cooked just enough to kill any harmful bacteria that may be present.

Modern-day practitioners of the paleolithic diet must be careful to get necessary nutrients found in foods that are not on the diet. For example, milk and other dairy products are a major source of calcium and vitamin D for most people following the conventional Western diet. Late Paleolithic people probably got sufficient calcium from wild vegetables and from gnawing the bones of animals they ate^[4]. Vitamin D can be synthesized by the body upon sufficient exposure to sunlight, and can be obtained from cod liver oil, and from oily fish such as salmon, mackerel, sardines, and tuna^[7]. Since cultivated vegetables have less calcium than their wild counterparts, since excessive exposure to sunlight has been linked to skin cancer, and since it can be expensive to eat fish several times a week, many followers of the diet may choose to take calcium and vitamin D supplements to be sure they get enough of these nutrients.

Benefits

The benefits of a paleolithic diet are, as with most dietetic theories, widely debated.

There are however a number of medically diagnosed conditions whose sufferers have been shown to benefit directly from specific components of the diet. Some examples of this include:

Coeliac disease, a gastrointestinal disorder whose sufferers are unable to digest the proteins gluten and casein, found in wheat and milk respectively.^[8]
Dermatitis herpetiformis, a skin disorder linked also to digestability issues related to gluten.
Gluten ataxia, a common neurological manifestation of gluten sensitivity.^[9]
Other conditions linked anecdotally^[10], albeit unproven, to gluten and/or casein proteins include

Other key health benefits commonly associated with and supported by this theory include:

Reduction or elimination of grains, dairy, and refined sugars in the human diet has shown to lower glycemic load. This is thought to lower risk of diabetes and other related syndrome X diseases by placing less stress on the pancreas to produce insulin, and preventing insulin sensitivity.
Increasing intake of fruits and vegetables induces a net base load, as opposed to the net acidic load on the body when eating a grain based diet. This is believed to prevent osteoporosis by passing less calcium salts through the kidneys.
Animals that have been fed a pastural diet (free-range beef and chicken) instead of grain fed animals tend to have higher ratios of omega-3 fatty acids and other nutrients.
By reducing the intake of processed foods the sodium/potassium ratios in the body are more balanced.

Support

Phytic acid, a chemical present in grain, is a strong chelator of important minerals such as calcium, magnesium, iron, and zinc. It, in essence, 'binds up' these minerals, and since humans lack the digestive enzyme phytase required to break this bond, these important minerals are not bioavailable, contributing significantly to mineral deficiencies. This problem is increased when dietary mineral supplements are not available, such as in developing countries.

High reliance upon cereal grains is likely to yield a positive NEAP (NET ENDOGENOUS ACID PRODUCTION) that in turn could increase the risk for osteoporosis, and other diseases of acid/base imbalance.^[11]^[12]

A high consumption of cereal grains, even whole grains, is likely to result in a high glycemic load diet, which in turn increases the risk for Obesity, Diabetes and other diseases of the metabolic syndrome.^[13]^[14]

Lectins present in cereal grains and legumes have the potential to cause auto-immune diseases, like reumathoid arthritis, by a process called molecular mimicry (similarity of structure shared by products of dissimilar genes).^[15]^[16]

Regarding milk and dairy products, these foods were never consumed by hunther-gatherers, prior to the advent of agriculture.^[17]After weaning, there's no mammal in the world that consumes milk (and from another species).Lactose intolerance can be a problem to many people around the world, although fermented dairy is often tolerated.There are links between bovine milk consumption and type 1 diabetes^[18], prostate cancer^[19], multiple sclerosis^[20], and Crohn’s disease^[21].The final problem posed by some dairy products is its high insulin response. Despite having a low glycemic index, milk, yoghurt and cottage cheese are highly insulinotrophic, having an insulin index similar to white bread.^[22]^[23]^[24]

Criticism

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Mass economic sustainability: The paleolithic diet does not take advantage of the lowered cost of calories for energy from grain and starchy vegetable (such as potato) carbohydrates, as well as the nutrients of calcium, fortified nutrients in processed foods, proteins and fiber. This is a staple of the majority of the world's larger and more modern populations. No studies have been done into the viability of the economic side effects of instating a wide-scale paleolithic diet, and if the farming is sustainable for large populations. Without such studies, it is difficult to know if there would be enough food to feed everyone. Some see overpopulation as the problem.
Unnecessary farming expenses: Neolithic diets permit people who are not the best hunters and gatherers to nonetheless thrive, and this has led to the prosperity of modern society. This is because more people with more specialized roles are freed of the need to hunt and gather, instead spending time in the pursuit of science and medicine. If the paleolithic diet unnecessarily proscribes foods that are efficient sources of the essential nutrients for humans, it results in food costs that are higher than necessary and thereby reduces quality of life by cutting into disposable spending.
Unnecessary food storage expenses: Providing fresh food free of preservatives on a large scale would introduce logistical challenges that would increase costs to producers and retailers. The advantages gained by using foods that are designed for longevity in storage would be lost. These additional costs would make food less affordable.
Calcium: Unless one were to eat the bones of the meat, a paleolithic diet could risk being low in calcium. Vegetables like broccoli may serve to provide some, but milk and other dairy products are a much higher source. Nonetheless, in many East Asian and South-east Asian diets where dairy products are rare, fish and seafood is consumed as a source of calcium. For example, some small fish (eg. anchovies) have bones soft and small enough to chew. Although eating small fish along with the bones is uncommon in Western cultures, it can be a source of calcium. Also calcium needs are reduced when the intake of base producing fruits and vegetables is high.
Vitamin D: Vitamin D can be produced through synthesis of sunlight and cholesterol, but this is sometimes not realistic due to the time spent indoors or circadian rhythms of modern society, and ignorance of needs due to varying skin pigmentations. It may also not be desirable or safe. Milk is often fortified with vitamin D; by omitting milk and other fortified foods, society will have to rely on exposure to sunlight to avoid deficiency. While it can be obtained through other sources (such as cod liver oil), these are not well known, readily available, or readily affordable sources.
Protein: Dairy, like meat, is an excellent source of complete protein, as an alternative to eating meat for obtaining all of humanity's essential amino acids. This is especially so in the case of whey protein isolate, removed from the much-maligned majority casein protein in milk. Such alternate protein sources may be useful for those trying to lower cholesterol, who want a faster flux of proteins for faster tissue repair, or who have trouble digesting meat (especially if not cooking it). That animal milk is not equivalent to human milk only means that an infant or adult cannot use it as their entire diet, not that it can't be a beneficial part of it. Nothing toxic has been identified about milk that is free of hormones, antibiotic resistance, and is pasteurized.

One criticism of the Paleolithic diet is that it is possible that the human body has indeed evolved to some extent since early man. Small changes in the human body could still have occurred within the time frame from early in the paleolithic up until recent times. For example, populations that have had agriculture for a while, may have had the time to adapt to it, at least to a small extent (microevolution). One example is lactose intolerance. Although most modern humans retain the ancestral feature of not being able to digest the sugar lactose which is found in milk after weaning from their mother's milk, the populations (mostly Europeans, Arabs, Indians, and the Maasai) that raised animals for dairy, did indeed evolve the ability (lactose tolerance) to digest it. Since there could have been changes to our body design (albeit small ones) since the last Ice Age, it may not be true that what was good for the Stone-age humans is good for modern people. As a counterpoint, the ability to consume lactose is not a large genetic leap, as we are already adapted to consume human milk; i.e. milk is much less objectionable from an evolutionary perspective when contrasted with other foods that are disallowed.

Many modern innovations (e.g. cooking, pasteurizing and inspecting food quality) have contributed greatly to our health, longevity and well-being. The paleolithic diet certainly does not object to improved food quality. Additionally the paleolithic diet does not frown on fire as it was available for a few hundred thousand years; hence cooking is also allowed.

Cautions about poisoning

As the consumption of raw foods gains popularity, some unsafe foods have occasionally entered the human diet. It should be pointed out that it is generally accepted among the supporters of paleolithic nutrition that while it is necessary to eat only those things that can be consumed raw, it is not necessary or advisable to eat those foods raw. Many foods can harbor dangerous pathogens, including, among other things, salmonella, norovirus, and Trichinella spiralis, many of which can have serious health consequences if not first killed by means of heating, i.e., cooking. For this reason, cooking is allowed of things that, under normal healthy circumstances, would not require cooking to be consumed (grains still being discounted).

The heating to an adequately high temperature of meat, poultry, and fish will normally destroy harmful bacteria and in worse cases parasite eggs (such as tapeworm). Raw eggs can also contain many harmful substances, most commonly salmonella. However, recent studies have shown that the level of salmonella infection found in commercial eggs is negligible.^[25]