The Developmental Trajectory and Correlation of Human Milk Microbiota and Oligosaccharides in Taiwanese Lactating Mothers

Human milk microbiota (HMM) and human milk oligosaccharides (HMOs) are crucial components of breast milk that influence infant health and development. This study provides long-term insights into the dynamic changes in HMM and HMOs and their interactions among Taiwanese lactating mothers. A cohort of 90 mothers with singleton, full-term infants contributed 319 breast milk samples across eight lactation stages over 52 weeks. HMOs were quantified using mass spectrometry, while milk microbiota composition was analyzed through 16S rRNA sequencing. Our findings reveal that HMO concentrations steadily declined from birth to 52 weeks postpartum. The most abundant HMO was 2'-fucosyllactose (2'-FL, 18.8%), followed by 3-fucosyllactose (3-FL, 16.5%). Notably, 2'-FL levels decreased over time, while 3-FL concentrations increased. Other HMOs exhibited a general downward trend throughout lactation. HMM composition also shifted dynamically, with significant variations in α-diversity and β-diversity across lactation stages. The predominant bacterial genera-Streptococcus, Pseudomonas, and Staphylococcus-showed distinct bimodal temporal patterns. Correlation analyses revealed that tetratose and sialylated HMOs were positively associated with Bacteroides abundance, while multiple HMOs negatively correlated with Streptococcus. These findings underscore the complex interactions between breast milk oligosaccharides and microbial communities, highlighting their potential implications for infant gut health. Further research is needed to explore the clinical significance of these transformations and their role in shaping the early-life microbiome. PRACTICAL APPLICATIONS: This study shows how breast milk changes over time, with certain sugars (HMOs) decreasing and others shifting, while beneficial bacteria also fluctuate. These changes may influence an infant's gut health and development. Understanding these patterns can help improve infant nutrition, guide breastfeeding recommendations, and support the design of better infant formulas or probiotics.