BIFI-OBESE: Clinical Trial in Paediatric Obesity

Obesity is a major, public health concern that affects at least 400 million individuals and is associated with severe disorders including diabetes and cancers. Worldwide, the prevalence of overweight and obesity combined in children, adolescents and youth, between 1980 and 2013, increased to 47.1%, with alarming data also in developing countries. Obesity is often caused by imbalance between excessive caloric intake and reduced physical activity. Recently, microbial changes in the human gut was proposed to be another possible cause of obesity and it was found that the gut microbes from fecal samples contained 3.3 million non-redundant microbial genes. However, it is still poorly understood how the dynamics and composition of the intestinal microbiota are affected by diet or other lifestyle factors. Moreover it has been difficult to characterize the composition of the human gut microbiota due to large variations between individuals. The role of the digestive microbiota in the human body is still largely unknown, but the bacteria of the gut flora do contribute enzymes that are absent in humans for food digestion. Moreover, the link between obesity and the microbiota is likely to be more sophisticated than the simple phylum-level Bacteroidetes: Firmicutes ratio that was initially identified, and it is likely to involve a microbiota-diet interaction. Obese and lean subjects presented increased levels of different bacterial populations. It is hypothesized that the obese microbiome is set up to extract more calories from the daily intake when compared to the microbiome of lean counterparts. In addition, a caloric diet restriction impacted the composition of the gut microbiota in obese/overweight individuals and weight loss. In lean subjects there are Coriobacteriaceae, Lactobacillus, Enterococcus, Faecalibacterium prausnitzii, Prevotella, Clostridium Eubacterium, E. coli and Staphilococcus. By contrast, Bifidobacterium, Methanobrevibacter, Xylanibacter, Bacteroides cha