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Leche and Tiny Health Launch First Clinical Study of Donor Breast Milk’s Effect on Formula-Fed Infants’ Gut Health
Business Wire
Mon, July 20, 2026 at 9:30 PM GMT+5:30
4 min read
The 100-family trial will measure whether a small daily amount of donor breast milk shifts a formula-fed infant’s gut toward a healthier, more breastfed-like pattern
GILBERT, Ariz., July 20, 2026–(BUSINESS WIRE)–Leche, the first shelf-stable, consumer-driven donor breast milk, and Tiny Health, the at-home microbiome testing company for every stage of life, today announced a joint clinical study examining how donor breast milk affects gut health in formula-fed infants. It is among the first studies to apply modern microbiome science to donor milk specifically, and the first to measure what happens when a small daily amount is added on top of formula
“For years the conversation has been breast versus formula, as if those are the only two options a family gets,” said Trish Clifford, co-founder of Leche. “Most parents end up somewhere in between, and until now nobody has actually studied what that middle ground does for a baby’s health. We built Leche because donor milk deserved to be a safe and accessible option instead of a workaround. This study is about giving that option the science to back it up.”
The science on breast milk’s role in infant gut development is well established. A baby’s gut is home to trillions of bacteria, and establishing the right ones early is linked to better digestion, immunity and long-term health. Research consistently shows that even a little breast milk helps grow those protective bacteria, largely because of human milk oligosaccharides, a family of roughly 150 to 200 sugars unique to breast milk that feed the gut’s good bacteria directly. Formula can now replicate one or two of them, but real breast milk, including powdered donor milk, delivers the full range, since the sugars survive pasteurization intact.
What has not been established, and what this study hopes to prove, is whether a modest daily amount of donor milk, layered into a formula-fed baby’s routine, moves the needle for the roughly two-thirds of American babies who receive and rely on formula at some point in their first year
“This is one of the first studies to examine whether adding a small, consistent amount of donor breast milk to an otherwise formula-fed infant’s diet can produce measurable shifts in microbiome composition and function,” said Cheryl Sew Hoy, Founder and CEO of Tiny Health. “Using shotgun metagenomics, we are eager to see whether babies’ gut microbiomes become better equipped to use the unique sugars found in human milk—and whether even a small daily amount can help beneficial bacteria take hold during this important window of development.”
