The intestinal microbiota – formerly called intestinal flora – occupies an important place in the health of individuals. Doctor, holder of a doctorate, professor of nutrition at the University Hospital of Rouen in France, the Dr Pierre Déchelotte devotes his research to it and directs the INSERM laboratory “Nutrition, Inflammation and dysfunction of the intestine-brain axis”. We spoke with this internationally renowned researcher.
Dr Déchelotte, why is the intestine called the second brain?
If the intestine is the second brain, the microbiota is the third brain. This third brain is located inside the second brain, and both speak to the first, the top one!
For regarding thirty years, we have shown that in our digestive tract, there are a lot of neurons, which explains why we spoke 20 to 25 years ago of the second brain. But it’s even more complicated than that.
We are familiar with the cells that absorb food, but there are also many immune cells that play a role in regulating the intestinal barrier. There are endocrine cells that produce many hormones that play important roles in the regulation of hunger and satiety, but also in the regulation of motricity and digestive sensitivity. All these cell types communicate with each other.
This intestinal brain must therefore be understood as something more global.
You have studied eating disorders, in particular anorexia nervosa, in connection with the microbiota. Could the development of an eating disorder start from the microbiota?
We have accumulated over the past 15 years a whole series of publications to suggest that part of the mechanism of the maintenance or even the triggering of anorexia, or perhaps other eating disorders such as binge eating or bulimia , might be linked to an imbalance of the microbiota.
There is indeed a dysbiosis, a significant imbalance of the microbiota, in anorexia nervosa. In bulimia, the data are still very limited, but we will publish new results soon. In binge eating, which leads to obesity, we are at the beginning of the story: our Belgian colleagues recently reported that the microbiota of compulsive patients is not the same as that of non-compulsive patients.
We have also done a lot of work on certain bacterial proteins that would be able to regulate food intake.
Your research was able to demonstrate that a strain of probiotics, now marketed in France, had a favorable effect on satiety and weight loss. Can you tell me more regarding it?
In a few years, we were able to show, effectively, first on animal models, then by a clinical study in humans, that the strain Hafnia alvei HA 4597 has a reinforcing effect on satiety and promotes weight loss in moderately overweight people.
However, it is not a treatment for obesity, but a food supplement that reinforces the natural mechanisms of satiety. We continue to search for other microbiota modulators that may be useful in nutrition. The Hafnia alvei HA4597 and Lactobacillus plantarum WJL strains (interesting for growth and renutrition) are already marketed in France and certain European countries by our start-up TargEDys and the Biocodex laboratory. For the others, you will have to wait a little longer.
Can improving the microbiota contribute to the recovery of people suffering from binge eating?
What we are currently saying in a hyperphagia patient is that one must first try to understand the mechanisms that led to the hyperphagia. There are often major stresses, anxiety-depressive disorders or other compulsive disorders. We will first treat the eating behavior with cognitive behavioral therapies, with food re-education and possibly with drugs, in particular serotoninergics, such as fluoxetine and sertraline, which work quite well on compulsive disorders.
But not all patients respond to these relatively standard treatments. It is therefore also necessary to re-educate the microbiota, and the best re-education begins with food. If we manage to calm the compulsions, which are generally on fatty and sugary foods, we will reduce the imbalance of the diet and gradually correct the dysbiosis. For example, by reducing sugars and fats, and increasing fibre, we will favor certain species, such as those which produce butyrate, and we will reduce a certain number of other species which are dependent on a massive intake of fat, and therefore, ultimately, we re-educate the microbiota first through food. But this is not always enough, hence the interest of a more direct intervention with certain very specific probiotics with assessed efficacy.
You have just arrived from an international congress on prebiotics. What’s new in this regard?
Indeed, the PROBIOTA 2022 congress, which has just been held in Copenhagen, brought together 400 researchers and industrialists from all over the world to take stock of recent advances. It is a field in strong expansion. Weight control remains an important issue, and our work was the subject of a plenary conference, as moreover the exciting developments of the team of Patrice Cani (Belgium) on Akkermansia Muciniphila, another strain which seems very beneficial in reducing the risk of diabetes.
There were also a lot of communications on the modulation of stress, anxiety, by the microbiota and certain probiotics. In short, the microbiota has not finished surprising us!
What do you think of microbiota analysis kits?
Currently, what is circulating as commercially available microbiota analysis is not satisfactory. […] But this is a field that is changing very quickly, and a new generation of more specialized tests and above all better accompanied on the medical level should soon see the light of day. We are also working on it.
♦ To know everything regarding the microbiota, you can get a collective work to which Dr.r Déchelotte participated in addition to other European experts.
♦ Intestinal microbiota and human health Jean-Michel Lecerf, Nathalie DELZENNE Elsevier Editions
