As already mentioned on this blog, we are born sterile and our gut microbiota begins to develop at birth. We know that breast milk plays an essential role in the composition of gut microbiota in newborns.
Spanish scientists from the Institute of Agrochemistry and Food Science (IATA – Instituto de Agroquímica y Tecnología de los Alimentos) and the Center for Public Health Research (CSISP – Centro Superior de Investigación en Salud Pública) have undertaken research to analyse the range of microbes (microbiota) found in breast milk and identify the factors that may influence its composition. Using in depth DNA sequencing, the bacterial composition of breast milk was studied at three different stages of the breastfeeding process: postpartum (colostrum), and after 1 and 6 months of breastfeeding. The first major discovery was the amount of different species present in breast milk from the very beginning – human colostrum contains more than 700 different bacteria!
By analysing the different factors that influence microbiota composition in breast milk, the researchers discovered major differences related to the type of birth. Breast milk from women who had an elective cesarean section is less diverse in its bacterial composition than breast milk from those who had a vaginal delivery or an intrapartum cesarean (non-elective) section. These findings suggest that the mother’s hormonal status during labour also plays a role. “The lack of signs of physiological stress and the hormonal signals of labour may influence the composition and diversity of microbes in breast milk,” said the authors.
The study has also shown the significance of pregnant women’s weight in relation to breast milk composition. Diversity in breast milk bacteria among overweight women, or those who gain more than the recommended weight during pregnancy, is reduced.
As breast milk is usually the first food given to babies, its composition has a direct influence on the development of gut microbiota, which will play an essential role in the development of newborns’ immune system.
For the study’s authors, the results open up new channels for designing strategies for infant feeding that can improve a baby’s health. “If the bacteria in breast milk discovered in this study were found to be important for the development of the immune system, adding them to formula milk could be a strategy to reduce the risk of allergies, asthma or autoimmune diseases”, they conclude.