Contributed by Azarene Foutouhi
The human gut microbiome is understood to perform useful and necessary functions that help to maintain a healthy body in a multitude of ways such as aiding in the breakdown of otherwise indigestible nutrients and providing a physical barrier against disease-causing bacteria. However, the acquisition of this dynamic community is less well understood. While it was previously thought that the womb was a sterile environment and a baby first encountered bacteria on the path through the birth canal, DNA sequencing has allowed us to detect bacteria in cord blood, amniotic fluid, and the meconium (the infant’s first bowel movement). It is yet undetermined whether the initial microbiota is delivered via the mothers blood or an ascending migration from the vagina through the cervix, but studies have shown that a mother’s milk has a great effect on her child’s microbiome, no matter where the child may have acquired it.
It has been shown that roughly one-third of human breast milk is comprised of complex sugars, which though indigestible by the baby, instead serve to enrich the ‘good bacteria’ while blocking binding sites of potentially disease causing pathogens. These components of breast milk serve as prebiotics that promote the colonization of the baby by the so-called good bacteria such as the genus bifidobacteria, which dominate the gut of breast fed infants. It is clear that breast milk has evolved to not only nourish the newborn, but also to shape its gut micobiota into a functional and protective system.
Nevertheless, the gut microbiome is dynamic and varies greatly even between healthy individuals. Understanding the development and maintenance of this complex system, especially in the individual’s early years will provide great insight into the relationship between one’s colonization by different populations and disease.