The gut microbiome is made up of all the resident bacteria and other microbes that have colonised our gastrointestinal tract. Running all the way from the mouth to the colon, the microbiome creates its own mini ecosystem in the same way that plants, animals and insects live together in their own delicate ecosystem in a rainforest.
The gut microbiome is not static. It changes throughout life after the first colonisation shortly after birth. Variation is highest during childhood and it gradually decreases with age. Illness, antibiotic use, fever, stress, injury and dietary changes all affect the blend of microbes that make up the microbiome.
The initial stage of gut colonisation during and after birth plays an important part in shaping the future health of an infant. Breastfed infants have a different microbial signature to formula-fed infants and this could explain some of the immune-enhancing protection that breastfeeding offers. Breast milk contains a diverse population of bacteria, but not as much is known about how the milk and physical contact of feeding can change the microbiota.
In a new study, researchers looked at 107 breastfeeding mother-infant pairs and measured the bacterial communities growing in the gut of the infant in the first few months after birth. Twenty-eight per cent of the gut bacteria in the infants were found to originate from breastmilk. A further 10 per cent of bacteria actually came from the skin around the mother’s nipple. Adding up to almost 40 per cent, breastfeeding is clearly an important source of bacteria for an infant.
Bacterial diversity is an indicator for a healthy microbiome. Infants who are breastfed had a more diverse microbiome and this increased with the amount of milk they received each day and even in the weaning period when solids were being introduced.
This research has identified another way that breastfeeding can contribute to the health of babies by seeding and feeding a thriving population of gut microbes.