Breast Milk Bacteria: The Key to Regulating Defecation Frequency Changes in Infants

Abstract Breastfeeding can significantly impact the establishment of the infant's intestinal microbiota. In this study, we hypothesized that maternal breast milk bacteria were associated with variations in defecation frequency in infants aged 1 to 6 months who were exclusively breastfed, and we sought to identify potential breast milk microbiota diagnostic markers. 102 exclusively breastfed infants aged at 1 to 6 months were enrolled in the study. Then, we collected their mothers' breast milk as samples for 16S rRNA sequencing evaluation of microbiotas. The results revealed a clear distinction between the three groups regarding microbiota structures and compositions. Changes were observed in the various species and genera, and the breast milk microbiota features Hydrogenobacteria, Serratia, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium were confirmed as potential biomarkers for regulating the change in neonate defecation frequency. This study demonstrates a significant correlation between the frequency of defecation in exclusively breastfed infants and the microbiota in their mothers' milk. It was discovered that the human breast milk microbiota may play a significant metabolic role in amino acids and oligosaccharides during its colonization in infants' intestines, which influences their defecation frequency. Our research provides new evidence and hypotheses regarding the association between infant defecation frequency and breast milk microbiome. Trial Registration This trial was registered on 22/12/2023 at www.chictr.org.cn as ChiCTR2300078973.