doi:10.1016/j.clnu.2025.106558engVázquez-Bolea, NataliaMora-Martínez, CarlosCuervo, MartaMartinez, J. AlfredoGil-Campos, MercedesLeis, RosauraBabio, NancyMoreno, Luis A.Corella, DoloresMoreira Echeverria, AnaAguilera, Concepcion M.Castro-Collado, CristinaPicáns-Leis, RosauraHernández-Cacho, AdriánMiguel-Berges, Maria L.Martin-Climent, PaulaJurado-Castro, Jose ManuelVázquez-Cobela, RocíoPlaza-Diaz, JulioRueda-De Torre, IsabelPastor-Villaescusa, Belénde la Torre-Aguilar, Maria JoséSalas-Salvadó, JordiSanz, YolandaNavas-Carretero, SantiagoGut microbiota composition and derived enterotypes are associated with ponderal status in preschool children. Childhood obesity risk assessment longitudinal study (CORALS) cohortART-2025-148379Summary Background and aims Childhood obesity is a growing public health concern increasingly linked to gut microbiota. We analysed associations between microbiota composition, functionality, and weight status in 1134 children aged 3–6 years from the CORALS cohort. Methods The baseline cross-sectional study stratified participants by weight status (underweight, normal weight, overweight, obesity) and performed shotgun metagenomic sequencing of stool samples. Analyses in R assessed alpha/beta diversity, taxonomic composition, enterotypes, and microbial pathways. Results Alpha diversity decreased with increasing BMI, particularly in obesity (Shannon adj.P = 0.00301; Simpson adj.P = 0.00158). Beta diversity revealed distinct microbial structures across groups (p = 0.001). Four enterotypes were identified: obesity was associated with Enterotype 3 (Segatella-dominated, p = 0.023), while Enterotype 1 (Alistipes, Akkermansia, Coprococcus) was enriched in underweight/normal weight. Species linked to obesity included higher Phocaeicola dorei (adj.P = 0.003) and Segatella hominis (adj.P = 0.001), and lower Longicatena caecimuris (adj.P = 0.03) and Blautia parvula (adj.P = 0.003). Functional analyses showed downregulation of vitamin and nucleotide biosynthesis pathways and reduced carbohydrate metabolism in overweight/obesity. Conclusions Gut microbiota composition and functionality are strongly associated with weight status in early childhood, suggesting microbial biomarkers and metabolic pathways relevant to understand early obesity development.2025http://zaguan.unizar.es/record/16947810.1016/j.clnu.2025.106558http://zaguan.unizar.es/record/169478oai:zaguan.unizar.es:169478info:eu-repo/grantAgreement/ES/MICINN/CEX2021-001189-Sinfo:eu-repo/grantAgreement/EUR/MICINN/PID2023-150693OBClinical Nutrition 57 (2025), 106558 [14 pp.]by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/openAccess