New research shows that Bifidobacteria transfer from mother to child

Both natural birth (as opposed to birth by C-section) and breastfeeding are topics that stir up a lot of conversation among mothers and the scientific community. For example, there is the question of whether breastfeeding rather than formula feeding has some specific benefit to an infant’s health. Well, what about the infant’s gut microbial health? A new article published by Applied and Environmental Microbiology takes a look at whether natural birth and breastfeeding coincides with an exchange of bacteria from mother to child.

Four mother and infant pairs were included in the study that was meant to discover whether the mother transfers any bacterial strains to the infant during vaginal birth and breastfeeding. In particular, the scientists were looking at the genus Bifidobacterium because this group has been known to be early colonizers of the infant gut. In addition, this genus has specific ways of digesting a human mother’s milk. Mother-infant pairs 2 and 4 exclusively breastfed, while pairs 1 and 3 supplemented with formula. Milk samples were collected from the mothers and fecal samples were collected from the mothers and children.

After sequencing the bacteria, B. adolescentis, B. angulatum, B. breve, B. dentitum, B. pseudolongum and B. thermacidophilum were found to be common between all of the mother and the infant fecal samples. The scientists then looked to see which bacteria were in both the mother’s milk and the infant’s fecal sample. The results suggest that the milk may be responsible for transferring B. adolescentis, B. angulatum, B. breve, B. longum and B. pseudolongum to the infant. Interestingly, there were also some bifidobacteria strains that were unique to the infant, suggesting that either they went undetected in the mother or that the infant was exposed to this bacteria from somewhere else.

After six months, samples were collected again in order to see how/if the sample compositions change. The scientists found that, especially in the infants, the abundance of bifidobacteria decreases. This is most likely due to changes in diet – less breastfeeding and more formula feeding – and perhaps environmental exposure. All in all, the results of this experiment shows that the infant microbiome might indeed be influenced by a vertical transfer of bacteria from mother to child. With more evidence of this as a possibility, science may begin looking into more complete analyses with larger study sizes.  

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