The microbiome is established immediately when we are born. At birth the baby acquires his or her microbial bacteria from the environment it is born into. For babies born vaginally, the first colonisation is from their mother’s vaginal, skin and rectal bacteria. For those born via caesarean section, these bacteria come from skin and the hospital environment.
A few hours following birth, a mucosal layer starts to form on the baby’s GI tract to act as a barrier to prevent pathogens from crossing into the gut. This mucosal layer is where the beneficial bacteria colonise, helping to reinforce the barrier and support immunity.
The development of the baby’s microbiome is then influenced by diet. Breast milk contains the mother’s bacteria and prebiotic oligosaccharides, which are the fibres that feed the bacteria and help them to colonise as part of the baby’s microbiome. If the baby is formula fed, he or she will not receive the ‘mammary microbiota’.
When the baby is weaned onto solid foods, the microbiome can be further supported by including fruits and vegetables for prebiotics and plain yoghurt and some fermented foods for probiotic bacteria.