It is believed that early colonization with diverse gut microbiota is important for the development of the immune system, particularly during the first 3 months of life. Among the most abundant members of the gut microbiota that colonize the gut of infants during early days of life are Bifidobacteria, which are believed to play a major role in the development of the immune system. However, the mechanisms by which the Bifidobacteria contribute to the development of a strong immune system have not been fully understood. In a randomized control trial at the Karolinska institute, researchers investigated the association between Bifidobacteria, their metabolites and immunoregulation during the first few months of life. In this study, exclusively breastfed full-term infants were randomized (n=20) to receive Bifidobacterium longum (subsp) infantis EVC001 daily for 21 days starting at day 7 or to receive breast milk alone (n = 20). Infants were followed up until they reached the age of 2 months. Fecal samples and blood samples from both groups (randomized and control) were collected on day 6 , 40 and 60 postnatal and analyzed for cytokine concentrations, non-targeted fecal metabolomics and metagenomics. Findings from this study showed that: