The intestinal microbiota composition and weight development in children: the KOALA Birth Cohort Study

ObjectiveTo investigate whether the intestinal microbiota composition in early infancy is associated with subsequent weight development in children.MethodsAnalyses were conducted within the KOALA Birth Cohort Study (n=2834). This cohort originates from two recruitments groups, pregnant women with a conventional lifestyle (no selection based on lifestyle) and pregnant women recruited through alternative channels (organic shops, anthroposophic clinicians/midwives, Steiner schools, and relevant magazines). From 909 one-month-old infants fecal samples were collected and analyzed by qPCR targeting bifidobacteria, Bacteroides fragilis-group, Clostridium difficile, Escherichia coli, lactobacilli, and total bacteria counts. Between the ages of 1-10 years, parent-reported weight and height was collected at 7 time points. Age- and gender-standardized Body Mass Index (BMI) z-scores were calculated. Data were analyzed using Generalized Estimating Equation.ResultsColonization with B. fragilis-group was borderline significantly associated with a higher BMI z-score of 0.15 (95% CI: -0.02 to 0.31), in the conventional subcohort. After stratification for fiber intake (pforinteraction 0.003), colonization with B. fragilis-group was associated with a 0.34 higher BMI z-score among children with a low fiber intake in this subcohort (95% CI: 0.17 to 0.53). Higher counts among colonized children were positively associated with BMI z-score only in children within the conventional subcohort and a high fiber diet (BMI z-score 0.08; 95% CI: 0.01 to 0.14), but inversely associated in children with a low fiber diet (BMI z-score -0.05; 95% CI: -0.10 to 0.00), and in children recruited through alternative channels (BMI z-score -0.10; 95% CI: -0.17 to -0.03). The other bacteria were not associated with BMI z-scores, regardless of subcohort.ConclusionUsing a targeted approach, we conclude that the intestinal microbiota, particularly the B. fragilis-group, is associated with childhood weight develop