Western diet, intestinal diseases, allergies and other ailments

All the "Big Mac" and other processed foods that people in the developed world consume can explain why they are more sensitive to allergies, autoimmune syndromes and inflammatory bowel diseases compared to the inhabitants of the agrarian (agricultural) societies.

All the "Big Mac" and other processed foods that people in the developed world consume can explain why they are more sensitive to allergies, autoimmune syndromes and inflammatory bowel diseases compared to the inhabitants of the agrarian (agricultural) societies.

New research suggests that people living in rural Africa have a healthier mix of microbes in their digestive tracts than their Western counterparts, a mix that likely protects them from intestinal diseases that are common in modern, developed countries.

The human gut contains trillions of bacteria - our microbiota - that help digest food and metabolize it, protect us from disease and train our immune system to identify and reject pathogens. The researchers hypothesize that the change in the microbiota is a co-evolution of the bacteria to change the nutritional composition. As the diet of our ancestors changed over time, so did the inhabitants of our digestive system, from microbes that could easily break down fibrous food in an earlier period to other bacteria, more suitable for digesting food containing animal proteins, sugars and starches that became more common after the development of reptiles and the domestication of animals, before approx. 10,000 years.

Modern sanitation together with medicine have also changed the types of bacteria that people encounter. Contrary to popular belief that developed countries have less disease, scientists hypothesize that these dietary and sanitary changes have made people in developed countries more susceptible and vulnerable to gastrointestinal disease and obesity, but have so far been unable to determine why.

A group of researchers headed by Paolo Leonti, a gastroenterologist from Italy, decided to compare the fecal bacteria of healthy children from the village of Burkina Faso, in West Africa, with those of healthy Italian children. The natural diet of the African children included foods with a high percentage of fiber, little fat and lots of vegetables. This diet reflects the food people ate at the dawn of the agricultural age, while the Italian children had a typical Western diet, which included little fiber and a lot of animal proteins, sugars, starch and fat.

The researchers found that the children from Burkina Faso had significantly more bacteria from the Bacteriodetes group than the Italian children and significantly less Firmicute bacteria. Previous studies in the field have shown that people who have more Bacteroidetes and less Firmicutes tend to be thin, while people with the opposite ratio are more likely to be obese.

In addition, the researchers discovered the strains of bacteria Prevotella, Xylanibacter, Treponema only in children from Burkina Faso. These bacterial strains are able to most efficiently break down fibrous foods and produce short chains of fatty acids, which provide additional energy. Studies have shown that these fatty acids also help protect the gut from inflammation, which could explain why inflammatory bowel disease is almost non-existent in African countries that eat a high-fiber diet, Leonti says.

The increased diversity of the bacteria in the gut also contributes to making the body more resistant to pathogens of the digestive system and moderates the immune response to molecules that are not harmful and thus, according to Leonetti, to a reduction in allergies.

"The intestine is the place where the digestive system meets the microbiota" says Leonti. According to him, in his group's research, the researchers were able to demonstrate that the nutritional diet is the most important component for obtaining a digestive system with a diverse microbiota and a healthy gut. Leonti also added that people living in Western countries can benefit themselves by changing the nutritional composition of their diet, so that it is more similar to the diet of the villagers from Burkina Faso. "If we change our diet, we will change our microbiota" he says "and thus we will improve our health".

Justin Sonnenburg, an immunologist at Stanford University in California, says the researchers did do a good job designing the study and that the results are impressive. According to him, this initial study forms the basis for a series of interesting future studies, among which it would be very interesting to conduct a crossover study in which people from each community (Burkina Faso and Italy) will change diets and then retest their fecal bacteria, so that we can learn how much of the variation described is on a hereditary basis.

of:

• Science
• PNAS