Human milk oligosaccharides (HMOs) are the third most abundant solid component of human breast milk and a key bioactive factor in early-life nutrition. This scoping review synthesizes current evidence on the role of HMOs in shaping the infant gut microbiota and supporting neonatal immune development. We searched PubMed, MEDLINE, Scopus, and Web of Science for peer-reviewed original studies, clinical trials, and review articles addressing HMO structure, microbial interactions, and immunological outcomes. The available evidence indicates that HMOs act as selective substrates for beneficial bacteria, particularly infant-type bifidobacteria, while also functioning as soluble decoy receptors that may reduce pathogen attachment to the intestinal epithelium. In addition, microbial fermentation of HMOs produces short-chain fatty acids that contribute to gut barrier integrity and may influence immune regulation. Emerging clinical studies suggest that specific HMO supplementation may support microbiota development and selected health outcomes in infants, although the evidence remains heterogeneous, and more longitudinal studies are needed. Overall, HMOs appear to play an important role in the early development of the gut microbiome and neonatal immunity, but further well-designed studies are required to clarify structure–function relationships and clinical relevance.
Szyszkowska et al. (Thu,) studied this question.