Breast Milk Sugars Shape Gut Microbiota During Weaning Period

Breast milk helps shape the gut microbiota for longer than previously thought. Researchers from DTU and Rigshospitalet have discovered that sugars in breast milk, which are nondigestible by the infant, so-called human milk oligosaccharides, HMOs, influence which bacteria thrive in the gut during the transition to solid food, and that this influence persists later in life.

The research findings have been published in the renowned journal Nature Communications.

“We have long known that breastfeeding is important for infants’ health. What is new is that we can now explain how the sugars in breast milk, HMOs, also help to select the bacterial communities associated with a healthy gut microbiota later in life. This underlines the importance of combining breastfeeding with solid baby food at this stage of child’s development,” says Maher Abou Hachem, professor at DTU Bioengineering and senior author of the study.

The study reveals a previously unknown mechanism that gives specific gut bacteria an advantage in the competition to inhabit the infant’s gut during weaning, because they are endowed to metabolise both HMOs from breast milk and fibres from plant-based foods.

The results suggest that the weaning period is a crucial developmental window, during which the combination of breast milk and solid food, promotes the maturation of the gut microbiota to the adult-like community that is maintained during adulthood. On the long term, this new knowledge may contribute to the development of better nutritional solutions for infants and strengthen our understanding of how early nutrition affects health later in life.

“The findings are important in daily clinical practice as an additional justification to the already strong emphasis on promoting the mother’s own milk production and breastfeeding when infants and young children are admitted to a neonatal intensive care unit due to preterm birth or critical illness,” says Consultant Lise Aunsholt from the Department of Intensive Care for Newborns and Young Children at Rigshospitalet.

“It is encouraging to know that when we advise a mother to continue breastfeeding after discharge – and for as long as possible during the transition to solid foods – this will potentially have a positive impact on the child for the rest of their life,” she says.

According to the researchers, the study shows that breast milk not only supports the infant’s nutrition during infancy but also helps to select the bacteria that become a permanent part of the gut microbiota later in life.

Close collaboration between DTU and TUH

The study was carried out in close collaboration between researchers from DTU and clinical research environments at the Technical University Hospital (TUH – see fact box)

The researchers analysed the changes in bacteria and their genes over the weaning phase. This gave them insight into which bacteria were present and what the bacteria were doing. At the same time, the researcherscultured the bacteria in the laboratory under conditions resembling the environment in the human gut. In this way, they were able to identify the bacteria capable of metabolising both HMOs from breast milk and dietary fibres from solid food.

“The collaboration between DTU’s technological and biological expertise and the clinical environments at TUH has been crucial in enabling us to link knowledge about the bacteria’s functions to the development of the gut microbiota in children. This provides unique insight into how early dietary choices affect health later in life,” says Maher Abou Hachem.

Could pave the way for new nutritional solutions

The researchers believe that this new knowledge sets the stage for the development of future nutritional solutions for infants and targeted interventions that support the establishment of healthy gut bacterial community.

The results also suggest that the weaning period may be a crucial time for preventive measures against diseases that are later in life associated with disturbances in the gut microbiota.