Gut-breast axis modulation through Streptococcus thermophilus TCI633 supplementation: a study on mother-infant microbiome dynamics

Breast milk provides essential nutrition and bioactive components, including probiotics, which contribute to the development of a balanced infant microbiota and a strengthened immune system. The gut-breast axis theory suggests that the maternal gut microbiota may influence the microbiota and composition of breast milk through immune-mediated signaling. This study aimed to investigate the colonization potential of S. thermophilus TCI633 in the infant gut and to explore its possible transfer via the gut-breast axis. A total of 30 exclusively breastfeeding mother-infant pairs were recruited. Mothers took TCI633 daily for one month following hospital discharge. Breast milk, maternal feces, and infant fecal samples were collected and analyzed for microbiota composition, S. thermophilus abundance, and detection of TCI633-specific gene fragments. Results showed minor changes in the microbiota composition of breast milk and fecal samples in the TCI633 group, with a slight increase in S. thermophilus abundance. Furthermore, TCI633-specific gene fragments were detected in 66.7% of infant fecal samples, suggesting potential microbial transfer and colonisation. These findings provide preliminary evidence supporting the feasibility of TCI633 transmission via the gut-breast axis, although further research is needed to determine its functional significance.