Breast milk boasts a weapon that influences the health of infants far beyond antibodies.
Science has recently shed light on a component of breast milk known as the complement system, which plays a crucial role in protecting babies against infections by shaping the bacterial composition of their gut. This discovery, stemming from research conducted by the Bloomberg School of Public Health at Johns Hopkins University, reveals previously unknown mechanisms through which breast milk promotes infant health.
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Scientists observed in mouse pups that those fed mouse milk lacking a key complement protein had a different intestinal microbial population compared to those breastfed with normal milk. This difference made the former particularly vulnerable to a specific pathogenic bacterium, Citrobacter rodentium, analogous to strains of E. coli causing diarrhea in humans. The study showed that complement system components in breast milk could directly eliminate certain bacteria in the gut, effectively protecting the young mice from infection.
These results, published in the journal
Cell, indicate that complement proteins in breast milk significantly contribute to the establishment of a protective gut microbiota during early development stages, enhancing child health and defense against pathogens. This protective activity is independent of antibodies, thus revealing a facet of the immunity conferred by breast milk.
Breastfeeding is recognized for its numerous benefits, providing optimal nutrition to infants and protecting them against certain infections through the sharing of antibodies and white blood cells from the mother. However, the precise role of complement proteins contained in breast milk was previously less understood. This study highlights their importance in modulating the infant's gut microbiota, offering increased protection against intestinal inflammation and infections.
These findings not only deepen our understanding of the protective mechanisms of breast milk but also pave the way for new research, particularly on the specific biology of complement proteins in breast milk and their role beyond the specific immune system.