How newborns are fed may impact their oral bacteria health

The feeding method of newborns could have an important role in the composition of the infant’s oral bacteria, according to a recent study. It doesn’t take long for the human mouth to become a melting pot of microbes after birth. And although Streptococcus species are dominant during the first six weeks of life, the bacterial population in the human mouth becomes more diverse with age. The study helps researchers understand the link between healthy oral microbiota and diseases.

The Mother-Infant Link

Researchers in Japan have released a new report detailing how mothers share oral microbes with newborns. Evidence indicates that a baby’s mother is the most important source of the initial oral microbiota. Scientists collected tongue samples from 448 pairs of moms and their infants. The samples were collected when the children were four months old to specifically measure the amount of amplicon sequence variants (ASV), which are unique DNA sequences shared between the mother and child.

Mother breastfeeding baby
. Infants fed with formula or a combination of formula and breastfeeding had more shared ASVs with their mothers than infants that were only breastfed. (Photo by Helena Jankovičová Kováčová from Pexels)

The results varied widely, with shared ASVs ranging from practically zero to 100% in newborns. “The acquisition level of maternal oral bacteria varied widely among individuals,” says senior author Yoshihisa Yamashita, Ph.D in a statement. The average amount of ASV shared between mothers and newborns was 9.7%, which was much higher than the amount of ASVs shared between newborns and other unrelated mothers. 

The most significant discovery, however, was that the feeding method of newborns had a direct influence on the amount of shared ASVs and oral bacteria composition. Infants fed with formula or a combination of formula and breastfeeding had more shared ASVs with their mothers than infants that were only breastfed. Of all the groups, breastfed infants had an oral bacteria makeup that diverged the most from the mothers. Other factors like mode of delivery, sex, or antibiotic use were found to have no impact on the abundance of ASVs.

Oral Health As An Indicator Of Disease

Scientists have two theories to explain their findings. “One is that protective factors of breast milk regulate mother-derived oral bacterial colonization,” says Yamashita. The second theory is that the different feeding methods of breastfeeding and formula alter the balance of oral bacteria. The study is unique in that it includes an in-depth examination of all 9 hypervariable regions in the 16s rRNA gene. Using ASVs allows for the analysis of DNA sequences that differ by as little as a single nucleotide, say scientists. 

Researchers at Kyushu University in Japan focus on the link between early oral bacteria makeup and the risks of disease later in life. Previous studies made some headway by examining the link between certain bacteria, cavities, and periodontitis. But new findings report that oral microbes can actually appear in the gut in those with conditions like IBS and colorectal cancer. The new findings are “vital as a foundation for further studies,” says Yamashita. A follow-up study is planned for the infants’ 3-year checkups to examine how the oral microbiota has evolved over time.

Find this study in the journal mBio.


Leave a Reply

Your email address will not be published.