Determinants of the gut microbiota in adolescence: a life-course analysis of diet and other factors

Background & aims: The human gut microbiota plays a key role in health. Factors shaping its composition and diversity have been widely studied during infancy and adulthood, but far less in adolescence, despite this being a key developmental stage. We examined the potential associations between the gut microbiota of adolescents and 82 variables measured from pregnancy to adolescence. Methods: Stool samples were collected from 366 adolescents (age range: 13-16 years) from two INMA cohorts (Spain), while a range of variables, including diet, lifestyle, sociodemographic factors, health status, antibiotic use, vaccination, COVID-19, anthropometrics, and pubertal development, were collected from pregnancy to adolescence. The gut microbiota was characterized using 16S rRNA gene sequencing and assessed using - and {beta}-diversity indices and individual taxa. Associations with the study variables were evaluated using linear models, permutational multivariate analysis of variance (PERMANOVA), and Microbiome Multivariable Association with Linear Models (MaAsLin2). Results: During pregnancy, vegetable intake was positively associated with -diversity and with both {beta}-diversity and the abundance of four genera (three inverse associations and one positive association). Legume intake was also inversely associated with two genera. During adolescence, cereal and pasta intake was positively associated with -diversity and {beta}-diversity, and was inversely associated with Bacteroides, whereas fish and seafood intake was inversely associated with -diversity. Other relevant variables measured during pregnancy and at birth, such as biological sex, parental social class, and maternal education, and during adolescence, such as antibiotic use, body mass index, and pubertal status, were also associated with {beta}-diversity indices and different taxa in both directions. Conclusions: Diet during pregnancy and adolescence, together with some anthropometric, clinical, and biological factors, appeared to play an important role in shaping the composition and diversity of the gut microbiota in this population of adolescents.