Intestinal flora: how is it formed?
Prof. R: Babies are born with a sterile intestine. The flora develops at birth during contact with the mother, breast milk being the best element to allow the child to build quality flora. This “installation” of bacteria in the intestine triggers the start of the immune system. The flora then evolves with age, becoming more and more diverse. An adult is home to about 400 different species of the 100,000 to 200,000 billion bacteria that make up their intestinal environment.
Intestinal flora: can it protect us against certain diseases?
Pr M. R: The balance of the flora, that is to say a certain relationship between “friendly” and “enemy” bacteria, is essential to be in good health. This helps fight intestinal infections and influences the type of cells that make up the lining of our intestines. It was recently discovered that the intestine has hormonal function. It secretes around fifty substances (peptides) which act at a distance through signals sent to the brain. Some intervene in the control of appetite, which gives rise to hopes for treatments against obesity and type 2 diabetes. A Finnish study has already shown that we can influence the weight by acting on the flora of obese people.
Intestinal flora: what disorders can occur?
Pr M. R: A disturbed flora can lead to an excess of intestinal permeability, and therefore the passage of undesirable proteins, such as bacteria or toxins. It can follow infections, of course, but also the installation of a small chronic inflammation. However, this situation could promote various diseases, such as obesity, type 2 diabetes
(or “fatty”), colon cancer, inflammatory bowel disease. Numerous teams in Belgium, France and the United States are working on these new avenues of research.
Intestinal flora: can our food preserve it?
Pr M. R: There are two complementary solutions allowing intervention on the intestinal flora. First, probiotics (yogurt, fermented milk, food supplements, etc.) provide new “friendly” bacteria. They are rather indicated on an ad hoc basis to correct intestinal disorders or to reconstitute the flora after an antibiotic treatment.
Prebiotics don’t quite have the same role. They provide specific “foods” to stimulate certain species of bacteria. The most widely used is inulin, derived from chicory. It also increases the fixation of calcium on the bone. It is found in plants (onions, leeks, artichokes, bananas, etc.), low-fat products and in the form of food supplements. Repeated cures can improve the body’s defenses.
Why is there interest in gut bacteria?
Prof. Marcel Roberfroid: In fact, we are in the process of rediscovering this flora, because we now have new techniques that are much faster. Twenty years ago, it took a year of work to analyze the flora of eight people. With molecular methods, it goes much faster. We thus realized that we did not know 80% of its composition! A thousand different species of bacteria have been identified.
