06/10/2026
A new study from Brown University has found that babies who are exclusively breastfed for at least three months develop unique chemical fingerprints in their bodies. Researchers analyzed DNA from 173 healthy infants and discovered distinct methylation patterns in the cheek cells and intestinal cells of breastfed babies that were not present in formula fed infants.
The study looked at methylation, a process where small chemical tags attach to DNA and influence whether genes are turned on or off without altering the underlying code itself. More than 450 genes showed different methylation patterns in breastfed babies, many of which are involved in metabolism, digestion, and immune function . The study accounted for other factors like maternal weight, age, income, and education to isolate the specific effect of breastfeeding.
The research suggests a potential mechanism for why breastfeeding is linked to lower rates of asthma, obesity, allergies, and gastrointestinal disorders later in life . The differences in DNA methylation were most pronounced in the cells of the intestines, which are the first point of contact for breast milk . The epigenetic changes were not permanent. The study tested all children again at age four and found the methylation patterns had largely faded, though it remains unclear if that erasure has any lasting health impact.