A recent study conducted by researchers at NYU Langone Health and the University of Manitoba has found that human breast milk plays a crucial role in regulating an infant’s microbiome during the first year of life, potentially lowering the risk of asthma. The study indicates that breastfeeding for more than three months fosters the gradual development of beneficial microbes in both the digestive system and nasal cavity, while early weaning—before three months—may disrupt this process and increase the likelihood of preschool asthma.
Key findings reveal that components in breast milk, specifically human milk oligosaccharides (HMOs), can only be digested with the help of certain microbes, giving these microbes a competitive edge. In contrast, infants who are weaned too early and switched to formula feed may host a different set of microbes better suited to digest formula. Although these microbes are common to all infants eventually, their early dominance in the gut has been linked to a heightened risk of asthma.
“Healthy microbiome development is not just about having the right microbes; timing and order of their arrival are equally critical,” explained Dr. Shenhav, an assistant professor at NYU Grossman School of Medicine.
The study also discovered that the bacterium Ruminococcus gnavus appeared earlier in the guts of infants who were weaned early compared to those who were exclusively breastfed. This bacterium is involved in the production of short-chain fatty acids and the metabolism of tryptophan, both of which have been associated with immune regulation and an increased risk of asthma.
Published online on September 19 in the journal Cell, the research tracked microbial changes in the guts and noses of infants participating in the CHILD Cohort Study, which has been monitoring 3,500 Canadian children from pregnancy through adolescence. By analyzing this data, researchers were able to distinguish the effects of breastfeeding from other environmental factors, including prenatal smoke exposure, antibiotic use, and maternal asthma history.
Despite these variables, breastfeeding duration emerged as a significant factor influencing the infant’s microbial composition over time. Researchers also developed a machine-learning model that successfully predicted asthma risk based on microbial dynamics and milk composition, revealing causal relationships that underscore the importance of breastfeeding in shaping the microbiome.
“The algorithms we developed provide valuable insights into microbial dynamics during an infant’s first year of life,” said Dr. Shenhav. “These insights enhance our understanding of how these microbes interact with the infant and their potential long-term health implications.”
The research emphasizes the need for data-driven national guidelines on breastfeeding practices and weaning. The authors suggest that further studies could help develop strategies to prevent asthma in children who cannot breastfeed for the recommended duration.
Funding for the study was provided by the National Institutes of Health and several Canadian research organizations. Alongside Dr. Shenhav and co-senior investigator Dr. Meghan Azad, the research team included experts from various institutions across Canada and the United States.
