A study led by Dr Emma Sweeney and Adjunct Associate Professor
Christine Knox, from QUT's Institute of Health and Biomedical Innovation, with
colleagues at the University of Queensland, showed that the growth of some
microbes was inhibited for up to 24 hours following breastmilk and saliva
mixing.
Dr Sweeney said the team's earlier
studies had found significant differences in the prevalence of key
bacteria within the mouths of breastfed and formula-fed babies and that
breastmilk and saliva interactions boost innate immunity by acting in synergy
to regulate the oral microbiome of newborn babies.
"Our findings suggest that breastmilk is more than a simple
source of nutrition for babies because it plays an important role in shaping a
healthy oral microbiome," Dr Sweeney said.
"Our previous research found that the interaction of
neonatal saliva and breast milk releases antibacterial compounds, including
hydrogen peroxide.
"Breastmilk is high in an enzyme called xanthine oxidase
which acts on two substrates, found in babies' saliva.
"The release of hydrogen peroxide from this interaction
also activates the 'lactoperoxidase system' which produces additional compounds
that also have antibacterial activity, and these compounds are capable of
regulating the growth of microorganisms.
"In this study, we exposed a variety of microorganisms to
breastmilk and saliva mixtures, and found that the growth of these
microorganisms was inhibited, immediately and for up to 24 hours, irrespective
of whether the microorganism was considered to be 'pathogenic' (harmful) or
'commensal' (normally found) in an infant's mouth."
Dr Sweeney said the composition of newborns' mouth microbiota
was an important factor in health and wellbeing.
"Changes to these bacterial communities in newborns have
important implications for infection or disease early in life," she said.
"While adult oral microbiota are stable, our studies have
shown that the microbiota in the mouths of newborns is much more dynamic and
seems to be altered by the mode of feeding within the first few months of
life," she said.
"The combination of breastmilk and saliva has been shown to
play an important role in shaping the healthy oral microbiota during the first
few months of life, but this also has significant implications for premature or
sick babies who are fed via a tube.
"In these cases, the mixing of breastmilk and babies'
saliva does not occur and so they do not receive the benefits of the
antibacterial compounds released during breastfeeding.
"Other researchers have shown that hydrogen peroxide can
remain active at pH levels similar to that of a baby's stomach, so we think
that this antimicrobial activity seen in the mouth may also continue within the
baby's stomach and intestines.
See:
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
