Microbiota and Body Composition During the Period of Complementary Feeding

Objectives: This study aimed to explore the associations between food group intake, faecal microbiota profile, and body composition during the period of complementary feeding. Methods: Diet was assessed using a quantitative food frequency questionnaire, faecal microbiota profile was assessed using 16S rRNA gene sequencing, and body composition was assessed using bioelectrical impedance analysis and dual energy x-ray absorptiometry, in a cohort of 50 infants aged 6 to 24 months of age. Results: During this critical period of microbiota development, age was the strongest predictor of microbiota composition with network analysis revealing a cluster of genera positively associated with age. A separate cluster comprised genera associated with fat mass index with Bifidobacterium showing the strongest correlation with fat mass index (rho = 0.55, P = 0.001, false discovery rate [FDR] = 0.018). Dairy intake was both negatively correlated with Bacteroides (rho = -0.49, P<0.001, FDR = 0.024) and positively correlated with lean mass index (rho = 0.44, P = 0.007, FDR = 0.024). Antibiotics use in the first month of life had the most striking influence on body composition and was associated with an increase in mean body mass index z score of 1.17 (P = 0.001) and body fat of 3.5% (P = 0.001). Conclusions: Our results suggested that antibiotics use in the first month of life had the most striking influence on body composition in this cohort of infants aged 6 to 24 months, whereas dairy intake interacted with both microbiota and body composition in early life.