Expert interview : Pr Patrice D. Cani

Are we destined to keep our extra pounds?

Broadly speaking, belief in a miracle cure is delusional. No treatment can beat obesity without the active participation of the subjects (diet, exercise, etc.) and an integrated and personalized approach to their care. Obesity is a long-term complex condition that depends on multiple related factors, including gut microbiota. However, to claim that an imbalance (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) in the microbial ecosystem inevitably leads to obesity (or conversely that a balanced one ensures a normal weight) is a mistake. It is nonetheless a good idea to maintain a balanced gut microbiota, which is part of a comprehensive and personalized treatment for patients.

Is it risky to act on microbiota on one’s own?

From a strictly medical standpoint, the approach is relatively safe, provided that consumers choose a probiotic¹⁷ whose advanced effects are based on scientific proof and whose bacterial composition is known (Lactobacilli (sidenote: Lactobacilli Rod-shaped bacteria whose main characteristic is the production of lactic acid, from where they get the name “lactic acid bacteria”.  Lactobacilli are present in the oral, vaginal and gut microbiota of humans, but also in plants and animals. They are found in fermented foods, such as dairy products (e.g. certain cheeses and yoghurts), pickles, sauerkraut, etc. Lactobacilli are also found in probiotics, with certain species recognized for their beneficial properties.   W. H. Holzapfel et B. J. Wood, The Genera of Lactic Acid Bacteria, 2, Springer-Verlag, 1st ed. 1995 (2012), 411 p. « The genus Lactobacillus par W. P. Hammes, R. F. Vogel Tannock GW. A special fondness for lactobacilli. Appl Environ Microbiol. 2004 Jun;70(6):3189-94. Smith TJ, Rigassio-Radler D, Denmark R, et al. Effect of Lactobacillus rhamnosus LGG® and Bifidobacterium animalis ssp. lactis BB-12® on health-related quality of life in college students affected by upper respiratory infections. Br J Nutr. 2013 Jun;109(11):1999-2007. ) and Bifidobacteria (sidenote: Bifidobacterium A genus of Y-shaped bacteria, most species of which are beneficial to humans. They are found in the gut of humans, and in some yogurts.

They:
- Protect the gut barrier 
- Participate in the development of the immune system and help fight inflammation 
- Promote digestion and improve symptoms of gastrointestinal disorders Sung V, D'Amico F, Cabana MD, et al. Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis. Pediatrics. 2018 Jan;141(1):e20171811.  O'Callaghan A, van Sinderen D. Bifidobacteria and Their Role as Members of the Human Gut Microbiota. Front Microbiol. 2016 Jun 15;7:925. Ruiz L, Delgado S, Ruas-Madiedo P, et al. Bifidobacteria and Their Molecular Communication with the Immune System. Front Microbiol. 2017 Dec 4;8:2345. ) for example). It is a myth to think that all probiotics are the same as the specific bacterial strain used plays a critical role in their action. Lastly, the consumption of prebiotics¹⁸ should also be encouraged. However, new users should particularly avoid taking excessively high doses as they might experience unpleasant side effects such as bloating, diarrhea, abdominal pain, etc. If truth be told, the greatest risk is a psychological one—namely being disappointed if promises are broken!

Has gut microbiota transplant been oversold?

Many studies are currently underway on the topic. Some of them show that transplanting microbiota would have no effect on obesity or that it would result in a temporarily improved ability to stabilize blood sugar levels. Results have been disappointing, but provided much valuable information. We now know that donor and recipient microbiota must be compatible. We have also learned that some individuals are more receptive than others to transplant (the same goes for dietary changes) depending on the initial composition of their microbiota. In any event, improving our health by focusing on gut microbiota is a promising avenue, as long as we act reasonably and follow medical and dietary recommendations. Personally, I am convinced of it as my motto is “In Gut We Trust”.