A food system with ‘murky’ evidence
Scientists highlight several phases in the evolution of the human diet. During the Paleolithic era, hunter-gatherers consumed a diet abundant in vegetables, fruits, nuts, and lean meats. The agricultural era, starting around 10,000 years ago, made grains, legumes, and dairy products essential. The Industrial Revolution introduced numerous “convenient” but unhealthy foods into the human diet, such as refined grains, canned goods, and hydrogenated oils. It is suggested that the dietary changes that occurred during the last two phases are responsible for many of today’s common diseases and the obesity epidemic.
Followers of the modern paleo diet advocate the theory of “stuck genetics.” This theory posits that any organism flourishes in an environment and on a diet to which it is evolutionarily adapted. Paleo dieters believe that humans evolved before the advent of agriculture. They argue that significant changes in the human diet over the past 10,000 years have occurred too rapidly for our genome to adapt. This lack of genetic adaptation results in metabolic disorders.
The central premise of paleo nutrition is that Paleolithic foods align better with our genetic makeup than the modern diet. Proponents claim that reverting our diet to that of hunter-gatherers can supposedly eradicate obesity and cure cardiovascular diseases, diabetes, and even cancer. To achieve this, they recommend eliminating a wide range of healthy foods from our diet.
Paleo dieters face significant opposition from some members of the scientific community, including evolutionary biologist Marlene Zuk. According to her, living beings, including humans, do not require tens of thousands of years to genetically adapt to new external conditions. In her book “Paleofantasies: What Evolution Really Tells Us About Sex, Diet, and How We Live,” she provides numerous scientific examples of rapid evolution in various organisms. One instance of recent human evolution is the ability to digest lactose. Zuk emphasizes that our genome can react quickly to dietary changes, and the assertion that dairy products and grains must be eliminated due to “stuck genetics” is a fantasy without scientific backing.
The question of when humans developed the ability to digest lactose remains a subject of scientific debate. An international team of scientists shed light on this issue by examining the genetic material of bones from Germanic tribes that lived around 3,200 years ago. Only 7.1% of these individuals possessed the lactose tolerance gene. Further analysis of the genome of people living in Germany approximately 1,500 years ago revealed that the prevalence of this gene had increased to 57%. This indicates that humans evolved rapidly after the Paleolithic era.
Many medical communities also critique the Stone Age diet. The British Dietetic Association (BDA) included it on their list of worst diets to avoid. The Paleo diet ranked second, just behind urine therapy.
BDA experts note that people often turn to a Stone Age diet to lose weight or alleviate gastrointestinal symptoms. Although they may achieve short-term goals, they often encounter serious health issues in the long term due to the absence of whole grains. Additionally, this diet is challenging to maintain; therefore, most paleo dieters eventually revert to a regular diet, leading to inevitable weight regain.
Experts from the Dietitians Association of Australia acknowledge that many elements of the paleo diet (fruits, vegetables) are indeed beneficial. However, they also highlight several drawbacks of this diet: it can cause deficiencies in minerals and vitamins and increase cardiovascular disease risk due to high consumption of coconut and butter, which contain saturated fats.
Over the past decade, numerous studies have illustrated some positive effects of paleo nutrition, such as weight loss, reduced inflammation, and improved management of type 2 diabetes. However, these studies are usually short-term and based on small sample sizes. Additionally, for every study supporting paleo nutrition, there are several others presenting opposing results. To accurately evaluate the effectiveness of paleo nutrition, larger and longer-term randomized trials are necessary, monitoring dynamic indicators of endocrine and cardiovascular systems in individuals with various diseases.
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Possible clinical effects
Several clinical studies involving small samples examined the effects of paleo nutrition on weight, BMI, and waist circumference. A six-month dietary intervention significantly reduced these parameters. The proposed mechanism for weight loss is the feeling of fullness that the diet induces. A longer study indicated that the weight loss effect is temporary, disappearing entirely after two years of dieting.
Six small trials reported positive effects of the paleo diet on glycated hemoglobin levels, blood insulin levels, lipid profiles, and blood pressure. However, three of these trials were inconclusive due to the absence of a control group.
The paleo diet’s effectiveness in reducing glycated hemoglobin may be attributed to its focus on low-glycemic index (GI) carbohydrate sources, which gradually raise blood glucose levels. In contrast, today’s popular Western diet contains many high-GI foods that induce hyperinsulinemia, hyperglycemia, and insulin resistance, leading to metabolic syndrome and diabetes.
Potential clinical effects of the paleo diet include a reduction in C-reactive protein, a marker of inflammation.
Inflammation levels in the body largely depend on the balance of polyunsaturated fatty acids, omega-3 and omega-6. The former are anti-inflammatory, while the latter can be inflammatory. The Paleolithic diet tends to be rich in omega-3, whereas the Western diet is high in omega-6.
Several studies involving patients with multiple sclerosis have evaluated the effectiveness of the modified Wahls paleo diet, which suggests consuming small amounts of legumes and gluten-free grains while limiting fish and animal protein. The Wahls diet significantly improved quality of life, eliminated chronic fatigue, and enhanced performance.
The principles of the Wahls diet are continually refined based on trial outcomes. It is quite possible that it may be incorporated into clinical practice in the future. However, as of now, there is no substantial evidence supporting the impact of this diet, or any other, on the progression of multiple sclerosis.
Health effects
Other research indicates negative effects of the paleo diet on lipid profiles. In one study, healthy participants adhered to a paleo diet for 10 weeks, resulting in elevated levels of “bad” cholesterol and reduced levels of “good” cholesterol.
Medical professionals also emphasize the nutritional imbalance of paleo diets due to the exclusion of various foods. Eliminating dairy products from the diet leads to individuals receiving only half of the daily calcium requirement. A deficiency in this mineral increases the risk of osteoporosis, complications during pregnancy, cardiovascular diseases, and cancer.
After following the paleo diet for two years, iodine deficiency may develop. The initial signs of iodine deficiency can occur within six months of dieting. The primary sources of this mineral are iodized salt and dairy products, both absent from paleo nutrition. To mitigate the risk of iodine deficiency, followers of the paleo diet are advised to take iodine supplements.
Australian researchers investigated the long-term impact of a paleo diet on gut microbiome composition and cardiovascular disease biomarkers. The experimental group consisted of 44 participants who had followed a paleo diet for over a year, while the control group included 47 individuals adhering to a traditional Australian diet.
The microbiota of the experimental group contained a high number of Hungatella bacteria, which produce TMAO, an organic compound whose excess significantly raises cardiovascular risk. Elevated levels of TMAO disrupt cholesterol metabolism, encouraging its accumulation in macrophages. Cholesterol-laden macrophages transform into foam cells, which contribute to the formation of cholesterol plaques. Atherosclerosis is a leading factor contributing to cardiovascular events and mortality.
The TMAO levels in the blood of paleo dieters were found to be 2.42 times higher than in the control group.
Researchers attributed the rise in TMAO-producing bacteria in the intestines of the experimental group to the lack of whole grain products in their diet, which normally protect the microbiome against Hungatella dominance.
Coconut oil, often touted by paleo dieters as super healthy, is particularly harmful to cardiovascular health. It consists of 90% saturated fatty acids (SFA), consumption of which is linked to an increase in “bad cholesterol” levels. Proponents of the paleo diet argue that the SFAs in coconut oil are of the medium-chain variety and do not contribute to cholesterol production. Some studies have even reported that coconut SFAs can reduce cardiovascular risk. However, higher-quality studies present conflicting evidence.
A meta-analysis of 16 studies demonstrated that coconut oil significantly raised “bad cholesterol” levels in comparison to non-tropical vegetable oils. The American Heart Association (AHA) reviewed seven controlled studies and concluded that coconut oil can lead to hypercholesterolemia.
In 2017, the AHA recommended replacing saturated fats (including coconut and other tropical oils) with unsaturated fats. Individuals at high cardiovascular risk should limit their saturated fat intake to no more than 6% of total calories (13 grams for a 2,000-calorie daily diet). One tablespoon of coconut oil contains 12 grams of saturated fat.
False efficiency autoimmune protocol
An even more “murky” subject is the so-called “autoimmune protocol” (AIP), a variant of the paleo diet that claims to possess miraculous properties for reversing autoimmune diseases. This diet is even more restrictive than the standard paleo diet, as it prohibits the consumption of eggs, nuts, and seeds.
The evidence supporting the effectiveness of the Autoimmune Protocol is considerably weaker than that for the Paleo diet. Its creator is biophysicist Sarah Ballantyne, who cites two studies on her website as evidence of the AIP’s therapeutic properties (due to a lack of alternatives). However, Ballantyne highlights only the strengths of these studies while omitting their weaknesses.
In 2022, the project Examine.com extensively reviewed the evidence supporting the diet. Both studies had very small sample sizes and significant methodological flaws. Experts at Examine.com labeled the results of the first study as “limited, low-quality data.” The second study cannot be deemed credible at all, as it was conducted by researchers with vested interests.
A Food System with ‘Murky’ Evidence
Scientists stand out several phases of human diet evolution. During the Paleolithic era, hunter-gatherers ate a diet rich in vegetables, fruits, nuts, and lean meats. The agricultural era, which began about 10,000 years ago, made grains, legumes, and dairy products indispensable. The Industrial Revolution saw the introduction of a host of “convenient” but unhealthy foods into the human diet, including refined grains, canned foods, and hydrogenated oils. It is hypothesized that the dietary changes that occurred during the last two phases — are the cause of many of today’s common diseases and the obesity epidemic.
Followers of the modern paleo diet promote the theory of “stuck genetics.” Any organism thrives in an environment and on a diet to which it is evolutionarily adapted. Paleo dieters believe that humans evolved before agriculture. Over the past 10,000 years, there have been colossal changes in the human diet, to which our genome has not had time to adapt. Lack of genetic adaptation leads to metabolic disorders.
The key idea behind paleo nutrition is that Paleolithic foods are more in line with our genetic makeup than the modern diet, and that if we “roll back” our diet to that of hunter-gatherers, we can supposedly get rid of obesity, cure cardiovascular disease, diabetes, and even cancer. To get rid of these diseases, they suggest eliminating a whole range of healthy foods from our diet.
Paleo dieters have some ardent opponents in the scientific community, such as: evolutionary biologist Marlene Zuk. According to the scientist, living beings, including humans, do not need tens of thousands of years to genetically adapt to new external conditions. In her book “Paleofantasies: What Evolution Really Tells Us About Sex, Diet, and How We Live,” she cites many scientific examples of the rapid evolution of various organisms. One example of recent human evolution is the ability to digest lactose. As Zuk points out, our genome reacts very quickly to changes in diet, and the assertion that dairy products and grains need to be excluded from it because of “stuck genetics” is a fantasy that is not supported by scientific data.
When humans learned to digest lactose is a topic of scientific debate. An international group of scientists spilled light on this issue. The genetic material of the bones of Germanic tribes that died about 3,200 years ago was examined. Only 7.1% of them had the lactose tolerance gene. Further examination of the genome of people who inhabited Germany about 1,500 years ago showed that the prevalence of this gene was 57%. This confirms that humans evolved rapidly after the Paleolithic era.
Many medical communities also oppose the Stone Age diet. British Dietetic Association (BDA) turned on and added it to the list worst diets to avoid. The Paleo diet came in second, behind only urine therapy.
According to BDA experts, people most often get hooked on a Stone Age diet to lose weight or eliminate gastrointestinal symptoms. In the short term, they achieve their goals, but in the long term, they obtain huge health problems due to the lack of whole grains. In addition, this diet is difficult to maintain, so most paleo dieters sooner or later return to a regular diet. After that, the lost weight is inevitably regained.
Experts from the Dietitians Association of Australia believe that many components of the paleo diet (fruits, vegetables) are indeed useful. However, along with the advantages, this diet has disadvantages: it provokes a deficiency of minerals and vitamins, and also increases the risk of cardiovascular disease due to the consumption of coconut and butter with a high content of saturated fats.
It is worth noting that over the past decade, there have been many studies demonstrating the positive effects of paleo nutrition: weight loss and reduced inflammation levels in the body, improved compensation for type 2 diabetes. However, as a rule, they are all short-term and based on small samples. In addition, for each such study, there are several others showing opposite results. To reliably assess the effectiveness of paleo nutrition, larger and long-term randomized trials are needed with control over endocrine and cardiovascular system indicators in dynamics in people with various diseases.
Possible Clinical Effects
In several clinical studies with small samples were studied The effect of paleo nutrition on weight, BMI, and waist circumference. The six-month dietary intervention significantly reduced these parameters. The proposed mechanism for weight loss is the feeling of satiety caused by the diet. A longer study showed that the weight loss effect is short-lived and completely disappears after two years of dieting.
Six small trials found positive effects of the paleo diet on glycated hemoglobin levels, blood insulin levels, lipid profiles, and blood pressure. Three of these trials were inconclusive because they lacked a control group.
The paleo diet’s ability to reduce glycated hemoglobin may be due to its predominantly low-glycemic index (GI) carbohydrate foods, which slowly raise blood glucose levels. The popular Western diet today contains many high-GI foods, which provoke hyperinsulinemia, hyperglycemia, and insulin resistance, leading to metabolic syndrome and diabetes.
Possible clinical effects of the paleo diet include a reduction in C-reactive protein, a marker of inflammation.
The level of inflammation in the body largely depends from the balance of polyunsaturated fatty acids omega-3 and omega-6. The former have anti-inflammatory properties, while the latter are inflammatory. The Paleolithic diet contains a lot of omega-3, whereas the Western diet is rich in omega-6.
Several studies involving patients with multiple sclerosis have evaluated the effectiveness of the modified Wahls paleo diet, which recommends eating small amounts of legumes and gluten-free grains but limits fish and animal protein. Wahls significantly improved quality of life, eliminated chronic fatigue, and increased performance.
The principles of the Wahls diet are constantly being improved based on the results of trials. It is quite possible that in the future it will be introduced into clinical practice. However, to date, there is no significant evidence of the effect of this diet, or any other, on the course of multiple sclerosis.
Health Effects
Other research demonstrates the negative impact of the paleo diet on lipid profiles. In one study, healthy subjects maintained a paleo diet for 10 weeks, which resulted in increased levels of “bad” cholesterol and decreased levels of “good” cholesterol.
Doctors also point out that imbalance in paleo diets in terms of nutrients occurs due to the restriction on the consumption of many foods. Due to the exclusion of dairy products, people get only half their daily calcium requirement. The lack of calcium increases the risk of developing osteoporosis, pregnancy complications, cardiovascular diseases, and cancer.
After two years of following the paleo diet iodine deficiency may arise. The first signs of iodine deficiency are observed after six months of dieting. The most important sources of this mineral are iodized salt and dairy products, which are excluded from paleo nutrition. To prevent iodine deficiency, adherents of the paleo diet are recommended to take iodine supplements.
Australian researchers studied the effect of a long-term paleo diet on the composition of the gut microbiome and biomarkers of cardiovascular disease. The experimental group included 44 subjects who had been on a paleo diet for more than a year, while the control group had 47 people who adhered to a traditional Australian diet.
The microbiota of the first group contained many Hungatella bacteria that produce TMAO, an organic compound whose excess significantly increases cardiovascular risk. High levels of TMAO disrupt cholesterol metabolism and promote its accumulation in macrophages. Macrophages overloaded with cholesterol can turn into foam cells, which cause cholesterol plaques to form. Atherosclerosis is a determinant of cardiovascular catastrophes and can lead to death from them.
The TMAO content in the blood of the subjects on the paleo diet was 2.42 times higher than in the control group.
The scientists linked the increase in the number of TMAO producers in the intestines of the first group to a lack of whole grain products in the diet, which help the microbiome maintain balance against the dominance of Hungatella.
A very harmful product for the cardiovascular system is coconut oil, which paleo dieters advertise as super healthy. It contains 90% saturated fatty acids (SFA), the consumption of which is associated with increased ‘bad cholesterol’ levels. Supporters of the paleo diet emphasize that the SFAs in coconut oil are medium-chain and do not participate in the production of cholesterol. There have even been published results of several studies indicating the ability of coconut SFAs to reduce cardiovascular risk. However, higher-quality studies show the opposite.
A meta-analysis of 16 studies found that coconut oil significantly increased levels of “bad cholesterol” compared to non-tropical vegetable oils. The American Heart Association (AHA) reviewed seven controlled studies stating the ability of coconut oil to provoke hypercholesterolemia.
In 2017, the AHA recommended replacing saturated fats (including coconut and other tropical oils) with unsaturated fats. They advised individuals at high cardiovascular risk to consume no more than 6% of their total daily calories from saturated fat (13 grams for a 2,000-calorie daily diet). One tablespoon of coconut oil contains 12 grams of saturated fat.
False Efficiency: Autoimmune Protocol
An even more “murky” story is the so-called “autoimmune protocol” (AIP), a restrictive variant of the paleo diet that is credited with magical properties of reversing autoimmune diseases. It prohibits eating eggs, nuts, and seeds.
The evidence for the effectiveness of the Autoimmune Protocol is weaker than that of the Paleo diet. Its developer is biophysicist Sarah Ballantyne. On her website, she cites only two studies as evidence for the therapeutic properties of the AIP. However, Ballantyne only informs readers about the strong points of the studies and omits the weak aspects.
In 2022, the project Examine.com conducted a detailed study on the evidence base for the diet. Both studies had very small sample sizes and gross methodological flaws. The results of the first study were described as “limited, low-quality data” by Examine.com experts. The second study cannot be considered credible, as it was conducted by self-interested researchers.
