Results from the IceGut study: tracking the gut microbiome development from mothers and infants up to five years of age.

The infant gut microbiome plays a critical role in the early development of the immune system, brain function, metabolism, and defense against pathogens. However, data from underrepresented populations, like Iceland, with its distinct dietary and lifestyle habits, remain limited. This paper presents the initial findings from the Icelandic Diet and the Infant Gut Microbiome Development (IceGut) study. Fecal samples were collected at multiple time points, representing 328 unique study identifiers, with one to five samples per child, from before the introduction of solid foods up to 5 years of age, and postpartum samples from 214 mothers. Microbial composition and predicted functional potential were assessed using 16S rRNA gene sequencing. Children in the cohort followed typical gut microbiome maturation, but at 1 year of age, they showed a notably higher relative abundance of IMPORTANCE: This study provides the first comprehensive analysis of gut microbiome development in Icelandic children, covering the time from before the introduction of solid foods to 5 years of age. Although the overall developmental patterns of the gut microbiome in Icelandic children were similar to what has been seen in other studies, interesting differences were observed, such as a higher abundance of