What time you feed your baby may matter more than you think, because the 2 a.m. and 2 p.m. feedings are not delivering the same milk.
“When we look at the nutrient composition of these breast milk samples, there is so much that can change in a day, in a month, in a year,” said Blakely Lockhart, who studies infant brain development at the Fralin Biomedical Research Institute at VTC.
“Human milk has more melatonin at night and more antibodies when baby is sick,” Lockhart said. “We think there are more adaptations happening that science has yet to fully explore.”
A Pediatric Novice Research Grant from the Gerber Foundation will support Lockhart in exploring how these shifts may be timed to the infant’s changing metabolic needs.
Lockhart is a doctoral candidate in the Translational Biology, Medicine, and Health graduate program at Virginia Tech. She conducts research in the lab of FBRI Associate Professor Brittany Howell.
“Blakely’s work will not only further our understanding of the amazing dynamism that exists in milk, but will also provide the data needed to know if these changes are important for infant development,” Howell said.
Preliminary evidence in the Howell Lab suggests that time of day also changes the composition of signaling molecules that influence how infants metabolize the nutrients in human milk.
MicroRNAs play a regulatory role in the body, with the ability to switch protein-building biological pathways on and off. Lockhart hypothesizes that the microRNAs in human milk follow a daily rhythm, with levels increased in morning milk to align with the infant's peak period of energy demand.
“Mom might be delivering particular microRNAs to prime baby’s own metabolism,” Lockhart said.
Understanding these patterns could have important implications for infant nutrition. Formula-fed children have higher body fat in infancy and continue to face a 15 percent to 25 percent higher lifetime risk of obesity than breastfed infants, even when consuming similar calories.
To investigate these connections, Lockhart will compare microRNA levels in morning versus evening samples and track infant growth through the first six months of life. Infants whose mothers’ milk shows the greatest morning-to-evening differences in key microRNAs are expected to show the healthiest body composition during the six-month time frame.
“If they do, then there is a lot of work to be done to better mimic this characteristic of human milk,” Howell said. “This will only happen through designing better milk alternatives in parallel with thoughtful policies that will improve access to milk or any improved milk alternatives. Blakely will be uniquely positioned to really improve outcomes with this work.”
Lockhart hopes her findings will eventually guide how pumped milk is timed and stored, inform the next generation of formula, and strengthen the case for policies that give more families access to direct breastfeeding.
“Formula lacks these sorts of bioactive molecules entirely. So, whatever the benefits may be, formula-fed babies aren’t getting those same benefits,” Lockhart said. “But they could be.”
The Gerber Foundation's Novice Research Awards support young researchers whose work stands to improve nutritional and developmental outcomes in infants and young children.