Universiteit Leiden

The Paleo Diet: an evolution-based approach to nurture the brain and body

The Paleo Diet: an evolution-based approach to nurture the brain and body 'Healthy green broccoli vegetables' by Lockstockb

The paleo diet is an evolution-based approach to nutrition that is increasing in popularity due to its health benefits.

A Return to our Roots

An important question in evolution is what early humans of our species and other hominids were eating before modern civilization. Archeologists and anthropologists discovered that when primates left the forest (and later colonized the entire globe); they started consuming less fruit and more game meat. Not only did they their diet consist of more meat, some scientists suggest there is a theoretical basis that our increased meat consumption is what allowed for the substantial increase in brain size that has occurred from primates to early hominids and to humans (brain size has roughly tripled from early hominids to modern man).

A Metabolically Expensive Brain

Characteristics of a species do not evolve by themselves, they require selection pressure. Our big brains are no different and there must’ve been an evolutionary advantage to developing a larger, more metabolically expensive brain during the evolution of hominids.
While brain size increased, something else was shrinking, namely our gastro-intestinal (GI) tract. When we compare the human GI tract to those of other species, we can observe that our digestive system started to become more similar to those of carnivores, who typically have a smaller gut. This change can be explained by the fact that meat is easier degradable as compared to the highly fibrous grasses and plants an herbivore would consume. There is a reason why a cow has more compartments to its stomach than humans do.

Hunter-Gatherer Lifestyle

These facts have implications for the way we conduct our lives and the way we eat, digest and metabolize food. Homo sapiens has been around for approximately 200.000 years, and hominids date back to 2.9-3.9 million years ago. These species lived as hunter-gatherers up to around 10.000-13.000 years ago, when agriculture was invented, which marked the end of the Paleolithic era and the start of the Neolithic era.
Agriculture allowed for massive increases in population, due to an increase in food supply. A question to consider is whether quantity of available food is more important than the quality of food.

Nutrient Density

One of the drawbacks of modern society is that we are always trying to make everything as efficient as possible. In agriculture, the goal has been to squeeze every acre of land for the most crops possible, in order to yield as much food as possible. Substantial sacrifices have been made in the manufacturing of food in the past centuries.
If we look at the nutrient density of foods, we see that the recommended modern western diet is incredibly low quality. The amount of daily carbohydrates consumed by the average person today is way too high when compared to our ancestors, who got the bulk of their energy from fats. Many people have started to return to the initial hunter-gatherer diet that allowed our species to thrive in the first place.

Positive Benefits

A diet centered on vegetables and meat has as a benefit that it has a macronutrient distribution that is more balanced for our species. It contains a larger amount of complete protein, which allows for a healthy muscular development. Many people in modern society ingest a lack of quality protein and have a deficient amount of lean muscle mass as a result of this. Consuming adequate amounts of essential amino acids (proteins) is important, since the body can’t synthesize them. Some of these proteins serve as pre-cursors for important hormones and neurotransmitters in the body.
Additionally, eating Paleo provides a moderate amount of carbohydrates, balanced with roughly equal amounts of healthy fats (in grams, not calories). This will improve insulin sensitivity substantially. This implies stable glucose levels, less damage to arteries (healthier cardiovascular system), improved energy storage and retrieval (healthy amount of fat stores on the body) and a more functional cell metabolism (which results in more energy).
Also, eating the right kinds of fat in these amounts raises HDL cholesterol and lowers triglycerides.

Neolithic No-No’s

The easiest way to summarize what not to eat is to just not eat anything from after the invention of agriculture. These include grains, carbonated drinks, seed oils, dairy products and most starch. This is an easy model, but probably not the most accurate one. There are many different shades of paleo and every individual should customize their own style (also taken into account food tolerances and personal preferences). None-the-less, there are some broad guidelines that apply.
One of the biggest misconceptions about food in modern society is the idea that grains are healthy. Grains are incredibly high in carbohydrates that rapidly spike blood glucose. Grains contain little to no micronutrients and the protein it contains is of very poor quality. Aside from that, there are a host of anti-nutrients that disrupt digestion and micronutrient absorption in the gut. Any grain-based food has no place in a paleo diet.
Another big offender is sugar water (carbonated drinks); these drinks contain only empty calories that spike blood glucose and provide no nutrition.
The consumption of dairy, legumes, potatoes and alcohol is flexible and may change from person to person. It also largely depends on food tolerances.

The Paleo Diet

  • Vegetables: the bulk of food comes in the form of leafy greens (like lettuce, spinach, cabbage), cruciferous vegetables (cauliflower, broccoli) and other vegetables (carrots, beets, leek, etc.). These foods are incredibly high in micronutrients and an absolute must.
  • Meat, fish and eggs: excellent source of protein and healthy fats. There is a huge caveat here, which is the health of the animal. Always opt for local, organic meat from animals that were allowed to eat and live under their natural living conditions. If you don’t know the source, the source is probably not a pretty sight.
  • Healthy fats: Since our metabolism is primarily geared towards beta-oxidation (fat burning for energy) there are some foods that are excellent for maintaining a stable and healthy blood glucose level. Avocado’s, olives, coconut and grass-fed butter are perfect examples of these.
  • Herbs and spices: many of these show clear health benefits.
  • Fruit: consumed in moderation. Given the high glycemic load of most fruits, it does not take up a major portion of the diet. Opt for fruits high in anti-oxidants, such as berries.
  • Nuts and seeds: good source of fats and protein. Given the high amounts of omega-6, consume in moderation.
  • 100% dark chocolate: excellent source of fats, potassium and magnesium. Do not eat in candy bars with lower concentrations, they are loaded with sugar and soy.

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