The Paleo Diet is also called the Paleolithic Diet or the Stone Age Diet. The idea began in the 1970’s with the work of gastroenterologist Walter L. Voegtlin (Wikipedia article). But only recently has the diet become a popular success. Numerous authors have published books promoting this diet.
This particular criticism of the Paleo diet will focus on the version of the diet promoted by Loren Cordain, Ph.D. His website refers to him as “the world’s leading expert on Paleolithic diets and founder of the Paleo movement.” [The Paleo Diet website] And he is one of the most popular authors and promoters of the diet.
A section of The Paleo Diet website is entitled: The Paleo Premise. The page asserts: “The Paleo Diet is based upon everyday, modern foods that mimic the food groups of our pre-agricultural, hunter-gatherer ancestors.” Yes, that’s what it says: “mimic the food groups”.
One premise of the Paleo Diet is that “we are genetically adapted” to the eating habits of paleolithic man. The idea is that modern man evolved from our distant ancestors, from about 2.6 million years ago to the present, so that one particular eating plan would be the most healthy for everyone. The eating habits of human beings (and distant ancestors) prior to the time when agriculture began to dominate food patterns (about 10,000 years ago) is said to be healthier than the diet of agricultural society (10,000 years ago to the present).
There are several problems with this set of claims.
Behaviorally-modern humans are believed to have originated in about 70 to 50 ka (thousand years ago). After 50 ka, behaviorally-modern humans began to spread to distant lands. By about 30 ka, modern man occupied every habitable continent and many different ecological niches. Mankind lived by the oceans as well as far inland, in cold regions, temperate regions, and hot regions, in forests, on plains, on mountainsides and in nearly every livable habitat.
And until the rise of agriculture, modern humanity ate whatever foods were available in a particular location and in a particular season. Seafood was eaten, only if it was available. Game animals were hunted, when they were nearby. Some tribes followed herds of wild game, living a nomadic life. Other tribes remained in one location. Some relied more on game animals for food; others relied more on plants or fish. The food choices were limited, and they varied by season. There was never one unified diet of humanity, not for behaviorally modern humans (70 ka to present; homo sapiens sapiens), not for anatomically-modern humans (beginning about 200 ka; homo sapiens), and not for our distant ancestors, who are of the homo genus but not the sapiens species, nor the sapiens subspecies. Moreover, homo sapiens sapiens (modern man) has a much greater ability to obtain food from the environment than our distant pre-homo sapiens ancestors. This undoubtedly results in a substantially different diet.
The nutritional content of the foods available varied based on region. A number of paleo diet authors claim that the historical diet of pre-agricultural humans had a 1:1 ratio of omega-6 to omega-3 fat. But the omega-3 fat content of plants and fish varies greatly. Plants grown in very cold climates tend to have more omega-3 fat; the fat enables the plant to withstand cold temperatures because it remains fluid at low temperatures. Flaxseed grown in Canada today has a higher omega-3 content than flaxseed grown further south in the U.S. And this difference is even greater for different species of plants. The same is true for fish; the cold water fish are high in omega-3 fat; the warm water fish are not. So it is unsupportable to make a general claim that the varied diets of paleolithic man, living in many varied environments, had a certain amount or ratio of omega-6 to omega-3 fat.
Many of the foods we have today were unavailable to paleolithic humans in any region. Tomatoes developed, in only the last thousand years or so, from a small yellow berry in South America. There were no tomatoes in ancient times. Carrots were developed by agriculture from a wild plant, a small root (perhaps white or purple) with a hard core. Many of the fruits and vegetables of the modern supermarket were unknown or non-existent in ancient times, prior to the rise of agriculture 10,000 years ago.
So the claim that the Paleo Diet uses “modern foods that mimic the food groups” of our ancestors is quite an understatement. It is also perplexing to claim that paleolithic man had the healthiest diet, but we need only “mimic the food groups” to get the same benefit. Our ancestors had a diet that varied greatly depending on where they lived, and the foods in our supermarkets were largely unavailable to them. So it is quite a leap to say both that the best diet is theirs and that we can attain that best diet by eating foods they never ate.
The main premise of the Paleo Diet is that evolution has produced the perfect combination of diet and dieter in paleolithic man and the foods available to him. But evolution only aims to cause a species to survive to reproduce. The survival of the fittest is based on the survival and spread of genes by reproduction. There is no guarantee that a species and its diet will provide for a long life, beyond the reproductive years. Thus, evolution does not tend to provide genes or diets that would lengthen lifespan into a human being’s 60’s, 70’s, 80’s or beyond. Paleolithic man probably had an average lifespan in the 40’s (excluding infant mortality) [Nutrition and Health Science]. That is not what we want today.
Now there is at least one diet with proof that its eating pattern provides a long life: the Okinawan diet. The Okinawans live on an island, Okinawa, which is part of the nation of Japan. Their dietary habits have been studied by scientists because they have the highest percentage of centenarians of any group. But there is no similar evidence for the Paleo Diet. In fact, as I will show below, some of the food choices within the Paleo diet have been proven by scientific studies to increase the risk of disease and premature death.
In addition, there is a problem with the following claim, found on the Paleo Diet website:
“Decades of research by Dr. Loren Cordain and his scientific colleagues demonstrate that hunter-gatherers typically were free from the chronic illnesses and diseases that are epidemic in Western populations, including:
* Cardiovascular disease (heart disease, stroke, high blood pressure, congestive heart failure, atherosclerosis)
* Type 2 diabetes
* Autoimmune diseases (multiple sclerosis, rheumatoid arthritis, Crohn’s disease, ulcerative colitis, etc.)
* Myopia (nearsightedness), macular degeneration, glaucoma
* Varicose veins, hemorrhoids, diverticulosis, gastric reflux
Yes, there is much scientific evidence that a large set of diseases in Western society (including CVD, cancer, T2D, acne, obesity and other disorders) are caused by the most prevalent diet in Western society: the Western pattern diet. But the evidence is based on a comparison between Western societies (Western pattern diet) and other modern-day societies, whose diet is based on agriculture, not on hunting and gathering. The latter are largely free from the disorders caused by the Western pattern diet. For example, the Japanese traditional diet (rice, soybeans, fish, etc.), based on modern agriculture, provides for a greatly reduced risk of the so-called Western diseases (especially heart disease and cancer). But when Japanese persons adopt a Western pattern diet (in Japan or after emigrating), their rates for heart disease, cancer, and other diseases rise dramatically.
The claim on The Paleo Diet website, that hunter-gatherers are largely free from the diseases of Western society, does not prove that a diet based on agriculture is at fault. There are modern-day agricultural societies, which are largely free from the Western pattern diet and its concomitant medical disorders. Therefore, it is patently false to claim that hunter-gatherers are the only ones free from Western diseases, or that people today must adopt a paleolithic or ancient hunter-gatherer diet in order to avoid those diseases. It has been well-established by decades of scientific research that agriculture-based diets (including the Mediterranean diet) are also free from the diseases caused by the Western pattern diet. We need not go back to the alleged diet of paleolithic man — or a poor imitation of the same — in order to avoid diseases largely caused by the Western diet.
Nor do we need to avoid cereal grains, legumes, and dairy in order to avoid the Western pattern diet.
Which Foods are Paleo?
The pattern of foods allowed or rejected by the Paleo Diet is odd. The decision as to which foods are permitted is often contrary to modern scientific evidence on nutrition and healthy eating. The Paleo Diet rejects these foods:
Legumes (including peanuts)
Refined vegetable oils
Did ancient hunter-gatherers reject cereal grains, potatoes, and legumes? Unlikely. Modern agriculture developed domesticated cereal grains because pre-modern man ate wild grains. They ate whatever foods were available in their environment. They did not have the luxury of picking and choosing what to eat based on the latest fad diet. If legumes were available, they gathered them. If grains were available, these too would be gathered, ground, and eaten. Even today, there are some individuals and some societies who gather wild grains for food in times of scarcity Examples of wild grains include: drinn (Aristida pungens), kram-kram (Cenchrus biflorus), various Panicum species of grasses, and the wild rices of Africa (Oryza genus).
The modern potato developed from a wild plant with an edible tuber. The main factors that might make potatoes unhealthy is their preparation: as French fries, potato chips, baked with cheese, or topped with butter or sour cream. By comparison, an organic baked potato, eaten with the skin, is a healthy food choice. Paleo man would have eaten whichever roots and tubers were available, including the ancient version of the potato (still found in the wild in South America).
Refined sugar, in excess, is certainly unhealthy. But we don’t need to have recourse to an unsupported claim about paleolithic eating patterns to understand that fact. Modern scientific studies prove that consumption of excess added sugar is unhealthy.
A study published in JAMA Internal Medicine (Yang 2014) found increasing cardiovascular disease (CVD) mortality with increasing amounts of added sugar in the diet as a percent of total calories.  Compared to those persons who received less than 10% of their calories from added sugar, those with 10.0% to 24.9% of calories from added sugar were 30% more likely to die from CVD, and those with 25.0% or more calories from added sugar were 2.75 times more likely to die from CVD. To phrase this result another way, if a person in the highest category of added sugar intake were to cut their added sugar consumption to less than 10% of total calories, their risk of dying from CVD would be reduced by over 60%. But no studies show that small amounts of added sugar, even on a daily basis, do any harm to health.
 Yang et al., Added Sugar Intake and Cardiovascular Diseases Mortality Among US Adults; JAMA Internal Medicine. February 03, 2014. doi:10.1001/jamainternmed.2013.13563
Refined vegetable oils are not clearly linked to increased risk of any diseases. As long as an individual receives sufficient amounts, in the right proportions, of mono-unsaturated fat, omega-6 and omega-3 fat, with low intake of saturated and trans fats, refined oils can be part of a healthy diet.
A study, published in the American Journal of Clinical Nutrition (Buckland 2013), found that high consumption of olive oil reduced the risk of death from cardiovascular disease (CVD) — regardless of whether the oil was “cold-pressed extra-virgin” or ordinary refined olive oil. 
 Buckland et al., Olive oil intake and mortality within the Spanish population; American Journal of Clinical Nutrition. July 2012, vol. 96, no. 1, p. 142-149.
Both cereal grains and legumes are rejected by the Paleo Diet. Yet scientific evidence supports the consumption of whole grains and legumes as part of a healthy diet.
A study, published in the American Journal of Clinical Nutrition (Hu 2000), compared two dietary patterns: the Western diet and what they termed a “prudent pattern” diet.  The latter was characterized by higher intake of vegetables, fruit, legumes, whole grains, fish, and poultry. The diet of each participant was given a score based on how closely that diet conformed to one pattern or the other. The study found that a higher score for a prudent diet was associated with a lower the risk of coronary heart disease (CHD). The most prudent diet had a 30% reduction in risk of CHD. But the higher the score was for a Western diet, the greater the risk of CHD incidence. Participants with the highest scores for a Western diet had a 64% increase in risk of CHD.
 Frank B Hu et al., Prospective study of major dietary patterns and risk of coronary heart disease in men; American Journal of Clinical Nutrition. October 2000, vol. 72, no. 4, 912-921.
A study, published in the American Journal of Clinical Nutrition (Steffen 2003), found that “whole-grain intake was inversely associated with total mortality and incident CAD.”  In other words, the more whole grains a person eats, the lower the risk of death (from any/all causes combined) and the lower the risk of a diagnosis of coronary artery disease (CAD). But the Paleo Diet tells everyone to avoid grains.
 Lyn M Steffen et al., Associations of whole-grain, refined-grain, and fruit and vegetable consumption with risks of all-cause mortality and incident coronary artery disease and ischemic stroke: the Atherosclerosis Risk in Communities (ARIC) Study; American Journal of Clinical Nutrition. September 2003 vol. 78 no. 3 383-390.
A study, published in the American Journal of Clinical Nutrition (Deschasaux 2014), found that high intake of legume fiber reduces the risk of prostate cancer by 45%.  But the Paleo Diet insists that you avoid legumes.
 Mélanie Deschasaux et al., Dietary Total and Insoluble Fiber Intakes Are Inversely Associated with Prostate Cancer Risk; American Journal of Clinical Nutrition. February 19, 2014, doi: 10.3945/jn.113.189670
A study, published in Cancer Causes & Control (Lin 2005), found a 40% lower risk of colorectal cancer for persons with the highest intake of legume fiber.  Persons with a low intake of legume fiber had a higher risk of colon cancer. But the Paleo Diet insists that you avoid legumes.
 Jennifer Lin et al., Dietary intakes of fruit, vegetables, and fiber, and risk of colorectal cancer in a prospective cohort of women (United States); Cancer Causes & Control. April 2005, Volume 16, Issue 3, pp 225-233.
The Paleo diet also errs by insisting on a high intake of red meat and eggs. The What To Eat section of the Paleo Diet website suggests eggs for breakfast, “Sliced lean beef” as a snack, a “healthy” salad topped with “ground beef, beef slices, chicken, turkey, ground bison, pork chunks, etc.” for lunch, spaghetti squash topped with meatballs for dinner, or pork for dinner. The diet emphasizes a high intake of red meat (beef, pork, bison) and eggs. The site also suggests a glass of white wine with dinner, even though “wine would never have been available to our ancestors”. (By the way, red wine is healthier than white wine, due to a higher concentration of resveratrol and bioflavonoids.)
But modern scientific research — also not available to our ancestors — shows that high consumption of red meat and/or eggs is harmful to health.
A study published in JAMA Internal Medicine (Pan 2012), “Red Meat Consumption and Mortality”, found an increasing risk of death from heart disease and cancer with increasing intake of red meat.  A one serving per day increase in red meat consumption increased the risk of total mortality (overall risk of premature death from any/all causes combined) by 13% — that’s per serving per day. So eating two servings of red meat per day, compared to rarely consuming red meat, increases the overall risk of death by 26%. The same study found that a one serving per day increase in red meat consumption increased the risk of death from cardiovascular disease by 18%, and increased the risk of death from cancer by 10%. Again, that’s per serving per day. So you can double those numbers for two servings of red meat per day. But the Paleo Diet has no objection to one or two servings of red meat per day.
 An Pan et al., Red Meat Consumption and Mortality, JAMA Internal Medicine, April 2012; 172(7):555-563. doi:10.1001/archinternmed.2011.2287
The study’s authors suggest reducing consumption of unprocessed red meat to less than 42 g/day, which is less than 10 oz/week. So if you ate 2 meals that contained red meat per week, 5 oz/meal, you would be at that low level of consumption. Eating red meat twice a week is healthy; eating red meat twice a day is deadly.
Another study, published in American Journal of Clinical Nutrition (Pan 2011), found that increasing intake of red meat increases the risk of Type 2 Diabetes.  A one serving/day increase in total red meat consumption increased the risk of Type 2 Diabetes by 14%. This implies that a two serving/day increase results in a 28% increase in risk of T2D. The authors suggested substituting nuts, low-fat dairy, and whole grains for red meat: “We estimated that substitutions of one serving of nuts, low-fat dairy, and whole grains per day for one serving of red meat per day were associated with a 16-35% lower risk of T2D.”
 An Pan et al., Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis; American Journal of Clinical Nutrition. August 10, 2011, doi: 10.3945/ajcn.111.018978
But the Paleo Diet encourages the consumption of red meat daily, and rejects low-fat dairy and whole grains. According to the above study, that type of dietary pattern substantially increases the risk of Type 2 Diabetes.
The Paleo Diet also encourages the consumption of eggs, without regard to current scientific evidence. One study found that eating ≥1 egg/day increases risk of Type 2 Diabetes by 42%.  Another study found that eggs and poultry with skin each independently increased the risk of prostate cancer progression post-diagnosis.  A third study found that eating ≥ 7 eggs/week increased overall risk of death (total mortality from all causes combined) 23%. 
 Shin et al., Egg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysis in American Journal of Clinical Nutrition, July 2013, vol. 98, no. 1, p. 146-159.
 Richman et al., Intakes of meat, fish, poultry, and eggs and risk of prostate cancer progression in American Journal of Clinical Nutrition, March 2010, vol. 91, no
 Djoussé and Gaziano, Egg consumption in relation to cardiovascular disease and mortality: the Physicians’ Health Study in American Journal of Clinical Nutrition, April 2008, vol. 87, no. 4, p. 964-969.
Eating one or two eggs a week does not seem to have any adverse health effects; but like any food high in cholesterol, more is not better. A 3-egg omelet (extra-large eggs) has about 625 mg of cholesterol. That’s about the same amount of cholesterol as six hamburgers (6 oz. grass-fed beef per burger).
The American Heart Association recommends “a population-wide limitation of dietary saturated fat to <10% of energy and cholesterol to <300 mg/d."  You can't stay within those guidelines on a diet of daily red meat and eggs. The AHA also recommends:
"Consume a variety of fruits and vegetables and grain products, including whole grains.
"Include fat-free and low-fat dairy products, fish, legumes, poultry, and lean meats." 
 Krauss et al., AHA Scientific Statement, AHA Dietary Guidelines in Circulation, 2000; 102: 2284-2299.
You can’t adhere to the AHA guidelines for heart-healthy eating on the Paleo diet. It is too high in meat and eggs, and it rejects dairy, grains, and legumes. The Paleo diet is not based on current scientific research.
New research says cavemen did not follow a paleolithic diet