The study – published in Current Nutrition & Food Science – investigated whether the way infants are fed affects their health and the development of a healthy gut flora.
Led by Dr William Parker, an associate professor at Duke University Medical Center, USA, the team noted that while the benefits of breast milk have long been appreciated, their new work may have revealed a unique property that makes breast 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 Parker.
The research team said their findings may explain how breast milk, but not infant formula, helps to build colonies of gut bacteria in a newborn's intestinal tract, which in turn aid nutrient absorption and immune system development.
"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,” explained Parker.
"Knowing how breast milk conveys its benefits could help in the development of infant formulas that better mimic nature," he added.
"This could have a long-lasting effect on the health of infants who, for many reasons, may not get mother's milk."
In the new study, the US-based researchers grew bacteria in samples of infant formulas, cow's milk and breast milk. For the infant formula, the team tested three brands of popular milk, whilst whole milk was purchased from a grocery store. Breast milk was donated and processed to separate different components, including proteins, fats and carbohydrates.
The researchers also tested a purified form of an antibody called secretory immunoglobulin A (SIgA), which is abundant in breast milk and helps establish an infant's immune system.
Infant formulas, milk products and the SIgA were incubated with two strains of E. coli bacteria – which are necessary early inhabitants of the gut.
Within minutes, the bacteria began multiplying in all of the specimens, but there was an immediate difference in the way the bacteria grew, revealed Parker: 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 grew wildly, but grew as individual organisms that did not aggregate to form a protective barrier, the researchers said.
Parker said additional studies should explore why human milk has such a ‘clumping effect’ on infant gut bacteria, and whether it has a similar effect on strains of bacteria other than E. coli.
Source: Current Nutrition & Food Science
Volume 8, Issue 3, pp.168-176, (online here)
“Human Whey Promotes Sessile Bacterial Growth, Whereas Alternative Sources of Infant Nutrition Promote Planktonic Growth”
Authors: Angela Q. Zhang, S. Y. Ryan Lee, Melat Truneh, Mary L. Everett, William Parker