Beneficial bacteria in the mother’s breast milk and on the breast skin seed the infant gut microbiome and maintain it even after solid foods are introduced, according to a report published in JAMA Pediatrics.
Noting that little is known about the vertical transfer of breast milk microbes from mother to infant, researchers examined bacteria in samples from breast milk, areolar skin swabs, and infant stools in 107 healthy mother-infant pairs. The samples were obtained during a 5-year period from mothers and infants living in the community in Los Angeles and St. Petersburg, Fla., said Pia S. Pannaraj, MD, of the division of infectious diseases, Children’s Hospital Los Angeles, and her associates.
They found that bacteria from mothers’ milk and skin are transferred to infants’ guts. This transfer is most prominent during the first month of the infant’s life and declines over time as formula and solid foods are introduced. During their first 30 days, breastfed infants obtained a mean of 28% of their gut bacteria from breast milk and 10% from areolar skin, the investigators said (JAMA Ped. 2017 May 8. doi: 10.1001/jamapediatrics.2017.0378).The transferred bacteria are known to “have prominent carbohydrate, amino acid, and energy metabolism functions.” In addition, “The amount of daily breastfeeding as a proportion of total milk intake continued to influence the infant stool microbiome diversity and membership even after solid foods were introduced,” Dr. Pannaraj and her associates said.
These findings highlight “the importance of breastfeeding in the assembly of the infant gut microbiome.” They also support current World Health Organization and American Academy of Pediatrics recommendations “for exclusive breastfeeding during the first 6 months, with continued breastfeeding until at least 12 months,” the investigators added.