This article comes from the journal Science et Avenir – Les Indispensables n° 205 dated April/June 2021.
Thanks to genome sequencing techniques that, ten years ago, made it possible to identify previously unknown species in our intestinal flora, it is now estimated that approximately 100,000 billion bacteria, viruses, parasites and fungi are non-pathogenic in our small intestine. colon and colonize our colon. These microorganisms that make up the intestinal microbiota provide immune, digestive, neurological and metabolic functions. The microbiota of each individual, including twins, is absolutely unique.
A mature microbiota of about 3 or 4 years of age
This cocktail of microorganisms is formed in the first years of life. The microbiota is considered mature at about 3 or 4 years of age, even though its composition changes during life. At birth, the newborn absorbs vaginal bacteria from its mother, which then settles in her intestines. Therefore babies born by caesarean section are not exposed to these bacterial strains, and therefore the mode of delivery is one of the first differentiating factors. Genetics, taking medications, especially antibiotics, our clean obsession that drives us to hunt down all the microbes around us have an impact on the number as well as diversity of microorganisms present in our system.
But our intestinal flora also varies according to our plate. “Nutrition also very strongly determines the composition of our microbiota”, says Dominic Dardevet, a researcher at INRAe’s Human Nutrition Unit. “In industrialized countries where ultra-processed food has developed, microbial diversity is declining more markedly”, says INRAE researcher Anthony Fardet.
Treat yourself by modifying the microbiota?
Fibers nourish non-pathogenic bacteria; Probiotics and fermented foods maintain the richness of the microbiota (L.)Ibox again below) , Glutamine (an amino acid found in meat, fish, dairy products, grains and legumes) nourishes the intestinal wall. As far as omega-3 fatty acids as well as the polyphenols in fruits and vegetables (and red wine…), they are antioxidants and anti-inflammatory. Conversely, too much red meat leads to the production of carcinogenic compounds by the microbiota. And among them – many – food additives, some emulsifiers are linked to intestinal inflammation.
The list of maladies favoring such imbalances continues to grow: allergies, multiple sclerosis, colon cancer and even depression. Can some of them be treated by modifying the microbiota? Administration of probiotics, that is, live microbes with beneficial effects, or pre-biotics, to facilitate their growth, is one of the therapeutic strategies being studied. Be careful though. “The effects of nutrients are not the same in patients and healthy people”, warns Dominic Dardevet. “But the possibilities are huge! enthuses Isabel Savary-Auzeloux, a researcher at Inrae’s Human Nutrition Unit. For example, to promote muscle growth in the elderly, protein (Essential for maintenance of muscle fibers, editor’s note) are not enough, The new knowledge gained in recent years on the microbiota has led us to focus on probiotics, or fiber.” In a webinar on January 15, 2021, InRay’s Scientific Director Joel Doré announced: “We’re still a long way off from knowing which probiotics to give which individual, but over time, the microbiota opens the way to hyper-personalized nutrition.” Our microbes have a future!
Fermentation on the menu
Fermented foods do not make your mouth water. However, the microbiota loves it. Fermentation, this ancestral method of preservation, allows the multiplication of probiotics, these live microorganisms that permeate the intestinal flora. Bacteria with countless properties: They improve digestion – especially of lactose -, facilitate the assimilation of vitamins and other mineral salts, and prevent diarrhea associated with taking antibiotics. Beyond dairy products, the main sources of probiotics, sauerkraut, pickles, but drinks made from kefir grains, nourish the microbiota, a group of bacteria and yeasts. However, some processes such as cooking kill the probiotics. Suffice it to say that, in order to be beneficial, Alsatian sauerkraut should be replaced with fermented raw cabbage, and not without cold meat.
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