Breastmilk has long been considered "liquid gold" among clinicians treating premature infants in a newborn intensive care unit (NICU).
Prematures who are breastfed typically have better health than those who are fed formula. But the reason why it is the case has stayed a puzzle.
The difference is not solely due to the composition of breastmilk, according to recent research from the University of Maryland School of Medicine’s (UMSOM) Institute for Genome Sciences (IGS), which was published online in the journal mBio. Additionally, it is how babies metabolise it.
The Bifidobacterium breve bacteria, or B. breve, was found in the stomach of breastfed infants who received more breastmilk than their counterparts, according to research lead by Bing Ma, PhD, Assistant Professor of Microbiology and Immunology at UMSOM and researcher at IGS.
One week after birth, the preemies developed an unbroken intestinal wall, which improved their ability to absorb nutrients. In infants with “leaky gut,” B. breve was substantially less common in both formula-fed and breast-fed infants.
Infants who have a leaky gut do not form a barrier to stop microbes and partially digested food from entering the bloodstream. The team also discovered for the first time that the way B. breve metabolises breastmilk keeps breastfed infants healthy and promotes weight gain by fortifying their immature intestinal barrier.
Necrotizing enterocolitis (NEC), the third-leading cause of neonatal death in the United States and globally, can be brought on by an immature or “leaky” gut. Up to 10% of preterm neonates are affected by NEC, which has a devastating mortality rate of up to 50%.
“Our discovery could lead to promising and practical clinical interventions to strengthen the babies’ gut and, therefore, increase survival rates of the most vulnerable preemies,” said Dr. Ma.
Health advantages of bifidobacterium in the gut or microbiome have long been recognised. It contains a wide range of strains with quite distinct characteristics. Some strains are exclusively present in adults, whereas others are more prevalent in youth. Bifidobacterium infantis, one strain, is typically seen in full-term newborns.
113 premature infants who were born between 24 and 32 weeks gestation were followed by the researchers. This study only identified Bifidobacterium breve (B. breve) in preemies whose gut barrier function had improved within a week after delivery. The genetic ability of Bifidobacterium breve to digest nutrients within the cell membrane, as opposed to the more common external digesting method wherein bacteria release digestive enzymes onto nutrients to break them down, was found by Dr. Ma and her colleagues.
The gut microbiome of such breastfed premature infants with higher B. breve metabolises carbohydrates differently from that of formula, to put it simply. According to the experts, they believe that this metabolic process strengthens and develops the intestinal barrier more quickly, shielding vulnerable neonates from illness.
“We now know that it is not the breastmilk alone that helps preemies develop their intestinal barrier faster,” Dr. Ma said. “We will need to find the best way to prophylactically administer B. breve early in life, rather than rely on transmission from breastmilk or even the mother’s gut or vaginal microbiota during the birthing process. This is especially critical in formula-fed preemies.”
More research, according to Dr. Ma, is required to ascertain if the B. breve originated in the mother’s vagina, gut, breastfeeding, or even the environment.
Parvathy Sukumaran 
