Our modern way of consumption is not adapted to our body

Our modern food diseases do not come from nowhere. They would be, according to researchers at Princeton University (United States), the result of a poor adaptation of our body to the ultra-transformed nature and the carbohydrates that we eat in abundance. Our Western consumption patterns would have gone too fast for our evolution, which would be the cause of the explosion of current diseases that we have, such as obesity or certain cardiovascular diseases. The results of their study were published on October 21, 2020 in the journal Science Advances.

A diet that is too rich in relation to our evolution

According to researchers, the food we eat in Western countries is not suitable for our metabolism. Over the past two centuries, the industrial revolution and the modernization of agriculture have changed the way we eat. The foods we currently eat are easily accessible, high in calories, sugar, fat, and low in green vegetables and legumes. In fact, they are not in line with our sedentary work rhythms. These two factors combined are at the root of the increase in obesity and cardiovascular diseases that have plagued Western countries for almost half a century.

The Princeton researchers start from the premise that our ancestors had lifestyles and consumption patterns far removed from ours. Everywhere on Earth there have always been populations with agrarian, pastoral and hunter-gatherer lifestyles. Our ancestors did not have food present in abundance, the meals were not very caloric, the situations of famine were common, it was necessary to constantly move to find what to eat, which pushed their bodies to draw on their reserves , because they were conditioned for it.

With the Western way of food consumption, our body has not had time to adapt to all these changes. The result is a disconnect between human physiology, which evolved to cope with the way of life of our ancestors (meat and plant-based diet, lots of physical activity and food shortages) and that of our contemporary societies ( diet high in calories, carbohydrates, fat and sugar, a sedentary lifestyle and plenty of food). It is this discrepancy that would be at the origin of the diabetes, obesity and cardiovascular diseases that we have.

“Humans evolved in a very different environment than the one we live insays Amanda Lea, post-doctoral fellow at the Lewis-Sigler Institute for Integrative Genomics at Princeton University and author of the study. No diet is universally bad. It’s just about the mismatch between our evolutionary history and what we currently eat.”

The evolution of new globalized populations

To support their hypothesis, the researchers looked at several populations. In particular, they compared Western populations in Europe and the United States with peoples who kept a diet relatively close to that of our ancestors.

They were thus interested in the Turkana, a population living in an isolated desert in the north-west of Kenya and which derives its subsistence from its pastoral activity. Just as their ancestors did for thousands of years, the Turkana practice pastoralism in arid regions. Their diet depends largely on fresh or fermented milk from their cattle. They eat meat in small quantities (mainly camels, zebu, sheep, goats and donkeys) and take calories from the fat and blood of these animals. Occasionally they eat wild plants and may go to the market to buy grain, tea or oil.

However, with the rise of the market economy, part of the Turkana have abandoned the pastoral life for a life of traders for some (who live by making charcoal and selling the products made by their animals) and a completely urban for others. Thanks to this unique situation of comparison between the pastoral Turkana and the urban Turkana, it is thus possible to compare whether the change in their mode of consumption has an influence on their health.

“We realized we had the opportunity to study the effect of transitioning from a traditional lifestyle, based on almost 80% animal by-products – a diet extremely high in protein and fat, with very little or no carbs – to a mostly carbohydrate dietunderlines Julien Ayroles, assistant professor of ecology and evolutionary biology at Princeton University and principal investigator of the study. This presented an unprecedented opportunity: genetically homogeneous populations whose diet spans a lifestyle gradient from relatively ‘matched’ to extremely ‘unmatched’ to their recent evolutionary history.”

The same diseases as Westerners

By comparing the health of different groups of Turkana, the researchers could see that those who had kept their traditional way of life and those who had turned to trade were in excellent shape. On the other hand, those settled in cities presented all had cardiovascular problems, suffered from high blood pressure, diabetes or obesity. The results also showed that the more urban they lived, the less healthy they tended to be.

“We find more or less what we expectedannounces Julien Ayroles. Switching to this carb-based diet is making people sick.” His colleague Amanda Lea agrees. “There is a cumulative effect. The more you experience the urban environment — an environment ill-adapted to evolution — the worse it will be for your health”.

However, Julien Ayroles does not recommend adopting the same diet as the Turkana. “If you and I followed the Turkana diet, we would get sick very quickly. The key to metabolic health may be to bring our diet and activity level in line with that of our ancestors, but we have yet to figure out which components are most important.”