Journal Title (Medline/Pubmed accepted abbreviation): Scientific American
Volume: June 3
Summary of the article:
The Paleo dietThe Paleo diet is a diet that is based on the historical “hunter and gatherer” or “caveman” diet. Human ancestors of the Paleolithic period lived 10,000 – 2.5 million years ago. The diet promotes nuts, seeds, fruits and vegetables, and meat and excludes grains and dairy products. It forbids foods that humans hadn’t discovered/invented yet at that time including peanuts, lentils, beans, peas, and processed sugar. Advocates of the Paleo diet argue that our bodies are not “built” for food derived from modern agricultural processes and that food processing is the cause of “modern” diseases such as obesity, diabetes, and cancer.The Paleo diet is very controversial among all types of nutritionists. This article debunks myths associated with the actual diet of our ancestors during the Paleolithic period as well as discusses the pros and cons of the diet from a nutritional perspective.Some, but not all, aspects of the Paleo diet are undeniably healthy
The philosophy of the Paleo diet is flawed
- Most nutritionists agree that limiting highly processed foods (ex. products made from refined flour such as white bread and many breakfast cereals, products made from processed potatoes such as potato chips, deli meat, high sugar foods such as candy and ice cream, etc.) is a healthy practice. Many processed foods include high amounts of salt, preservatives, and refined sugar while offering little nutritional information.
- However, nutritionists disagree as to whether cutting dairy, whole grains, and legumes from the diet is healthful. These foods tend to be high in vitamins, minerals, and/or fiber, tend to be filling, and tend to not spike blood sugar.
The Paleo diet does not address the diversity of diets that existed in the Paleolithic period
- The Paleo diet assumes we are genetically identical to our ancestors that lived in the Paleolithic time period. This is not true; we have evolved to meet the changing demands of the environment.
- It is believed that humans (adults) in the Paleolithic period were lactose intolerant; that is why they avoided dairy. However, within about 7,000 years, some groups of humans have developed the ability to tolerate lactose in adulthood (not just in infancy). This illustrates that genes are not fixed, but that they can change and sometimes relatively quickly from an evolutionary timescale perspective.
- There is evidence of other large shifts in the genome such as the appearance of blue eyes, adaptations to the immune system and red blood cells to resist mosquito-borne diseases, and the composition of our gut microbiota. These shifts occurred in 10,000 years or less.
- Therefore, foods that inflicted discomfort and/or disease in the Paleolithic people may not elicit the same negative effects today. (Unfortunately, it is impossible to objectively test some of these theories).
- The Paleo diet philosophy does not address why this time period and not another (seemingly arbitrary) time period holds a diet that will maximize human health. Why not the common diet of humans in the Mesolithic archaeological period, or the Neolithic period?
The Paleo diet was not originally evaluated on an aging population
- Because of limited physical evidence, it is difficult to outline exactly how much and in what proportions food was consumed in the Paleolithic period. For example, what proportion of calories came from meat? When did humans begin eating grain?
- During the Paleolithic period, the humans consumed drastically different meals based on geographic location. It is unknown which diet is the “best” for protecting against modern disease. For example:
- The Inuits (near the Arctic circle) likely consumed upwards of 90% of their calories from meat and fish.
- In contrast, the !Kung people in Namibia, Angola, and Botswana likely consumed less than 10% of their calories in the form of meat and more than 50% from seeds and nuts.
- The Hadza people who live near Tanzania likely consumed about 50% of their diet from meat and fish and a large percentage (maybe 25%) of calories from roots.
- Additionally, humans’ diets varied vastly depending on season and opportunity. One thing we do know for certain that the body of a Paleolithic human was very adaptable and flexible to changes in available foods in a given environment.
It is not feasible to properly implement the Paleo diet
- Humans in the Paleolithic period lived typically to about 40 years old and many children died before the onset of puberty. “Modern diseases” are in part a result of the ability of modern medicine to preserve the function of various systems to different degrees. For example, a recent study investigated the bodies of ancient mummies from all over the world. In total, 47 of the 137 mummies showed signs of atherosclerosis. Thus, while heart disease might be considered a “modern disease” associated with the present lifestyle and diet in Western culture, it was also found in ancient cultures as well.
Modern hunter-gathers do not exhibit spectacular health
- Unfortunately, even if we wanted to consume food only consumed by our Paleolithic ancestors, it is not possible because the plants and animals have also evolved.
- For example, cabbage, broccoli, cauliflower, Brussels sprouts, and kale share the same distant relative. Even the uncultivated form, “wild cabbage”, probably differs from the wild cabbage 10,000 years ago.
- Corn and tomatoes have changed drastically to produce a palatable, hardy agricultural product.
- The Hiwi people are a modern hunter-gatherer society. They live in a savanna in Venezuela.
- Like humans in the Paleolithic time period, their diet changes throughout the year based on the seasons. During the rainy season, grasses are plentiful and, for protein, many Hiwi people hunt for capybara (related to guinea pigs, but much larger), deer, turtles, and other animals. During the dry season, they fish. They consume a large amount of roots as wells as nuts, fruits, honey, and one type of legumes.
- Their diet is not the stereotypical “Paleo diet”, though principles are similar. Less than 5% of their calories are derived from processed foods.
- The Hiwi people are not in the best health. Many are frequently hungry and, consequently, tired.
- Only about half of children reach adulthood and parasitic infections are rampant.
Key practice applications: The article is summed up concisely: “the Paleo diet is founded more on privilege than on logic”. Many of the “rules” for the diet are based not on nutrition science but arbitrary history. It is likely that consuming a “healthy diet”, i.e. one that includes fruits, vegetables, unprocessed meat, whole grains, and dairy while avoiding sweets and processed food will deliver similar health benefits as the Paleo diet.