Breast Milk's Magic Flora

Breast milk promotes a different gut bacteria growth than infant formulas

The benefits of breast milk have long been appreciated, but now scientists at Duke University Medical Center have described a unique property that makes mother's milk better than infant formula in protecting infants from infections and illnesses.


"This study is the first we know of that examines the effects of infant nutrition on the way that bacteria grow, providing insight to the mechanisms underlying the benefits of breast feeding over formula feeding for newborns," said William Parker, PhD, associate professor of surgery at Duke and senior author of the study. "Only breast milk appears to promote a healthy colonization of beneficial biofilms, and these insights suggest there may be potential approaches for developing substitutes that more closely mimic those benefits in cases where breast milk cannot be provided."



The infant formulas, the milk products and the SIgA were incubated with two strains of E. coli bacteria -- necessary early inhabitants of the gut that are helpful cousins to the dangerous organisms associated with food poisoning.

Within minutes, the bacteria began multiplying in all of the specimens, but there was an immediate difference in the way the bacteria grew. In the breast milk, bacteria stuck together to form biofilms -- thin, adherent layers of bacteria that serve as a shield against pathogens and infections. Bacteria in the infant formula and cow's milk proliferated wildly, but it grew as individual organisms that did not aggregate to form a protective barrier. The bacteria in SIgA had mixed results, suggesting that this antibody by itself isn't enough to trigger the beneficial biofilm formation.

"Knowing how breast milk conveys its benefits could help in the development of infant formulas that better mimic nature," Parker said. "This could have a long-lasting effect on the health of infants who, for many reasons, may not get mother's milk."


"This study adds even more weight to an already large body of evidence that breast milk is the most nutritious way to feed a baby whenever possible," said Gabriela M. Maradiaga Panayotti, M.D., co-director of the newborn nursery for Duke Children's and Duke Primary Care. "We know that babies who receive breast milk have better outcomes in many ways, and mother who breast feed also have improved health outcomes, including decreased risks of cancer. Whenever possible, promoting breast feeding is the absolute best option for mom and baby."



Study authors reported no conflicts of interest.