The gut microbiota: new hope in preventing childhood obesity?

Microbiota and obesity: dysbiosis in the hot seat

The gut microbiota, a real ecosystem lodged in our gut is essential for our health. As far as obesity is concerned. it is now known that a lack of diversity in the gut microbiota and the over-representation of some species of bacteria increases the risk of adiposity, insulin resistance and inflammation. So obese patients would have flora that is less rich than that of thin people even though the results are not yet unanimous.

Microbiota and obesity: risk factors

Apart from genetic factors, there are other factors that contribute to the development of obesity in children: The mother's diet during pregnancy, the method of giving birth, nutrition of the newborn (breast or bottle feeding), antibiotic treatment during childhood, etc. The biological mechanisms by which these possible risk factors will influence the development of obesity have not yet been clearly determined. However, the microbiota is suspected and a special interest is taken in it.

Microbiota and obesity: scientifically proven

It is obvious that obesity is a multi-factorial disease. It is therefore too early to raise an exclusive cause and effect link between the microbiota and obesity in humans. However, this link has been proved in animals where studies have shown that the “obese” characteristic can be transmitted from an “obese” donor mouse to a “thin” receiver mouse by faecal microbiota transplantation and vice versa. 

A single study has attempted to transplant the microbiota of thin people into overweight people. No reduction in the Body Mass Index (BMI) (sidenote: Body Mass Index (BMI) Body Mass Index (BMI) assesses the corpulence of an individual by estimating the body fat mass calculated by a ratio between weight ((kg) and height squared (m2). https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm https://www.euro.who.int/en/health-topics/disease-prevention/nutrition/a-healthy-lifestyle/body-mass-index-bmi ) has yet been observed.

Microbiota and obesity: when bacteria control our plate and our weight

Appetite/obesity, how does it work? The relationship between microbiota nutrition and obesity is complex. The modus operandi is as follows: food is digested and then the nutrients are metabolised by the bacteria. The molecules produced such as bile acids (sidenote: Bile acids Bile acids facilitate digestion and absorption of lipids in the intestine. They also exercise hormonal functions and are involved in various metabolic processes. The gut microbiota will modify the bile acids. In return the various bile acids will have an impact on its composition. Staels B, Fonseca VA. Bile acids and metabolic regulation: mechanisms and clinical responses to bile acid sequestration. Diabetes Care. 2009;32 Suppl 2(Suppl 2):S237-S245.  Li R, Andreu-Sánchez S, Kuipers F, Fu J. Gut microbiome and bile acids in obesity-related diseases. Best Pract Res Clin Endocrinol Metab. 2021;35(3):101493.  ) , short chain fatty acids (sidenote: Short chain fatty acids (SCFA) Short chain fatty acids (SCFA) are a source of energy (fuel) for an individual’s cells. They interact with the immune system and are involved in communication between the intestine and the brain. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020;11:25. ) or other molecules will in turn initiate certain mechanisms which will have an effect on obesity. For example, an altered microbiota will affect the control of fat storage and excessively increase energy recovery. The intestine and the brain will no longer be able to exchange correctly, with a disturbance in appetite and the feeling of satiety.

Microbiota and obesity: personalise our diet for better prevention

It is obvious that our diet has an influence on the composition of our microbiota. The child's microbiota will develop during the first years of life. It reflects his/her living environment and diet. For researchers, this period of life is important for carrying out dietary interventions. How? Via prebiotics which are naturally present in food and which the bacteria adore, and also due to probiotics, which are micro-organisms that we can ingest directly.

Adapting diet depending on the specific nature of one's microbiota. This new approach would provide better prevention of the risks of obesity from childhood onwards. And should this personalised diet become an ally of weight in the fight against obesity, a worldwide scourge which has almost doubled in the space of half a century¹? The range of possibilities - and hope - remains open...

^{1 https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight}