Relationship between the gut microbiota, diet, physical activity and obesity in children

Abstract

Introduction: Recent studies suggest that gut microbiota can participate in the pathophysiology of obesity. The aim of our study was to determine whether the composition of the gut microbiota is related to diet, physical activity and obesity in children. Methods: In this cross-sectional study 26 obese and 27 non-obese children aged 6-16 years were recruited. Gut microbiota in their fecal samples were analyzed by quantitative plating and quantitative real-time polymerase chain reaction (qRT-PCR). Matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identified species of the Bacteroides fragilis group. All children completed a dietary and physical activity survey. Results: Both quantitative techniques showed a negative association between BMI SDS and fecal concentration of Bacteroides fragilis group (β = -0.41 and -0.82; P = 0.033 and 0.013, respectively). MALDI-TOF MS analysis demonstrated a positive association between BMI SDS and B. fragilis colonization (β = 0.02; P = 0.049). B. vulgatis colonization was inversely associated with BMI SDS (β = -0.02; P = 0.033). BMI SDS was also positively associated with the Firmicutes/Bacteroides ratio (β = 1.87; P = 0.006). A higher intake of proteins (g/kg body weight) was associated with a higher colonization of Bacteroides fragilis group (β = 0.50 ; P = 0.043) and a lower presence of B. fragilis (β = -12.01; P = 0.032) in the gut. No significant associations were found for the level of physical activity. Conclusion: High intestinal Bacteroides fragilis group concentrations together with a low protein intake during childhood could lead to the development of obesity.