Pediatric obesity is associated with altered gut microbiota communities

Gut microbiota co-develops with its host from birth and is subjected to a complex interplay that is influenced by host genome, nutrition, and lifestyle. The goal of the present study was to compare the gut microbiota of obese and normal-weight children communities with short chain fatty acids production (SCFAs) and BMI z-scores to gain insights into the structure and activity of the microbiota in pediatric obesity. Seventy-eight children (36 males/42 females, 9-16 y) were enrolled at the Pediatric Department of San Paolo Hospital in Milan. Children’s BMI was calculated by reported weight/height2 (kg/m2), transformed to age and sex-specific z-scores. Fecal samples were collected, total bacterial DNA extracted and fecal SCFAs quantified by capillary electrophoresis. 16S rRNA gene sequencing was performed using Illumina MiSeq platform. Statistical analysis was made using the statistical software R. Intestinal microbiota of obese children was enriched in Firmicutes (N: 60.9±14.1, O: 72.1±12.1; mean±sd) and depleted in Bacteroidetes (N: 30±12.6, O: 16.6±11.8). Accordingly, the Firmicutes/Bacteroidetes ratio was significantly elevated in obese children (p<0.0001; N: 2.6 ± 1.83, O: 7.7 ± 7.1). We observed significantly higher concentrations of acetate, propionate, and butyrate, as well as total SCFAs, in feces of obese compared with normal-weight subjects (p<0.05 for all comparisons). BMI z-score and SCFAs were significantly correlated with microbiota composition at every taxonomic level (OTU to phylum; p<0.05) especially with Bacteroidetes and Firmicutes. Our results suggest that gut microbiota dysbiosis and elevated fermentation activity may be involved in the etiology of childhood obesity.