Breastmilk research could protect against deadly respiratory infections in babies

New breastmilk research could protect against deadly respiratory infections in babies Tue 4 Aug 2026 at 5:45am In short: A study from QIMR Berghofer Medical Research Institute has revealed clues into how a protein in breastmilk helps protect against potentially deadly respiratory infections in babies. Immunologist Simon Phipps led the study. He said researchers found a breastmilk protein that helps kickstart immune system development in early life. What's next? One expert says the biggest gains for mothers and babies in this area were likely to come from improving access to breastfeeding support. Scientists have uncovered strong clues into how a protein in breastmilk helps protect against potentially deadly respiratory infections in babies — a discovery they hope will improve commercial infant formula preparations. The international group of researchers found a breastmilk protein, osteopontin, triggers a cascade of biological processes that kickstart immune system development in early life. QIMR Berghofer Medical Research Institute immunologist Simon Phipps, who led the study, said it was known that breastfeeding was protective for babies against respiratory infections, but the underlying cause has been unclear. Scientists have also long known that osteopontin is found in high levels in a mother's breastmilk in the early weeks after birth, but how it influences infant health has been a mystery. Professor Phipps and colleagues compared the immune systems of baby mice fed osteopontin concentrated from cow's milk with those that were not given the protein after exposure to a respiratory tract infection. "The mice that weren't receiving the osteopontin in the milk, they had lower numbers of really important immune cells that helped defend the baby against the respiratory infection," he said. "If we supplemented the osteopontin then we could protect those baby mice from the infection." Microbiome changes Working together, dozens of scientists with different areas of expertise found osteopontin altered the baby mice's gut microbiomes. The microbiome is made up of different micro-organisms and develops in the digestive tract in early life. Professor Phipps said the osteopontin altered the production of bacterial metabolites — chemicals produced by bacteria — in the gut, which acted on cells, such as those lining the lungs in the infant mice, to turn on growth factors that boosted immune system development. The study, which was five years in the making and published today in the respected science journal Cell, also found a drug already used to treat type 2 diabetes could mimic the effects of osteopontin by activating the same immune processes in the mice. "It's really exciting," Professor Phipps said of the findings. His laboratory is in discussions with infant formula companies about using its research to help support and understand how different components in breastmilk could promote immunity in early life so that "when we make these discoveries, they take that on board and potentially improve the quality of the infant formula". The latest research in Cell was partially funded by infant formula manufacturer Nestle and Australia's National Health and Medical Research Council (NHMRC). Physiotherapist Bethany Kippen, who has been breastfeeding since giving birth to her first baby Billy late last month at Brisbane's Wesley Hospital, described the study as "really interesting". "Because I work in healthcare, I'm always looking for the most evidence-based practice, not just when I'm at work but also when it comes to making decisions for my family," she said. The 27-year-old said her breastfeeding journey was initially "really tough". "But once we got into a bit of a rhythm, and once we both started to learn a little bit more about how each other worked, then it's just the most rewarding experience," she said. "It's beautiful. I don't see it as just him receiving food and nutrients. I see it as a bit of a bonding moment, too. I love it." 'Exceptional science' Griffith University professor of nutrition and dietetics Ben Desbrow, who was not involved in the breastfeeding study, said it was "exceptional science". While he said the study was limited by being done in mice, "it does help us understand some of the fundamentals of how our body is likely to evolve and develop in the first few days, weeks, months of life in response to certain forms of nutrition that are supplied". "We know that high levels of osteopontin are associated with lower severe respiratory tract infections and other conditions," Professor Desbrow said. "We didn't understand how osteopontin might be linked with causation and that's what this work starts to unpack. We're building the picture of understanding more definitively exactly how these compounds are linked to the development of, and sustainability of, our immune system." While the study may inform improvements to infant formulas, Professor Desbrow said milk banks — where breastfeeding women donate their excess milk for other mothers' babies — may become increasingly important. "We know that it's challenging, and for some people, unfortunately, impossible to breastfeed, but it really highlights the importance of getting access to natural milk," he said. "The effects that we're seeing here are likely to have lifelong benefits to the individual. "Whilst it may reduce the likelihood of infections in neonates, it's also likely that lung conditions later in life are going to be associated with lung development in the early phase of life." Research fellow Lisa Stinson, of the University of Western Australia Centre for Human Lactation Research and Translation, said the study was "really strong foundational science" which underscored the value of breastfeeding and protecting the gut microbiome during the critical early-life window. But she said while mouse studies were "a great starting point", more work in humans was needed "before we can say anything definitive about what osteopontin is doing through breastmilk in babies". Griffith University Associate Professor Valerie Slavin, a maternity care and public health researcher, said while every finding about the importance of breastfeeding was "exciting", the biggest gains for mothers and babies were likely to come from improving access to breastfeeding support. "We know many women stop breastfeeding earlier than they had planned, often because they don't receive timely, practical or consistent support," she said. "We should also be investing in systems that help women achieve their breastfeeding goals."