In a finding that reinforces the importance of early-life nutrition, a large international study has found that babies who are exclusively breastfed for at least three months carry distinct biological markers in their blood—changes that may influence key processes related to immunity and development.
The research, led by the Barcelona Institute for Global Health in collaboration with the University of Exeter and the University of Bristol, was published in the journal Clinical Epigenetics. It is among the largest studies of its kind to explore how breastfeeding may leave a biological imprint on children.
Scientists examined blood samples from over 3,400 children as part of the international Pregnancy and Childhood Epigenetics (PACE) Consortium. Their focus was on epigenetics—subtle chemical modifications to DNA that do not change the genetic code itself but influence how genes are switched on or off. Specifically, they analyzed DNA methylation, a process that can be detected through blood tests and is known to regulate gene activity.
The study found that children who had been exclusively breastfed for at least three months showed higher levels of DNA methylation in genes linked to immune function and developmental processes, compared to those who had not been breastfed.
While the findings do not establish a direct cause-and-effect relationship between these molecular changes and health outcomes, they offer compelling biological evidence supporting what decades of public health research have already suggested—that breastfeeding plays a critical role in shaping early development.
“Our findings show that babies who are exclusively breastfed carry epigenetic changes associated with that experience. The genes that are affected by these markers are involved in developmental and immunity processes, but we can’t say from our study whether this affects those highly complex processes directly,” said Dr. Doretta Caramaschi of the University of Exeter, co-lead of the study.
The researchers emphasized that the results should be interpreted with caution, even as they open new avenues for understanding how early nutrition influences long-term health.
Dr. Mariona Bustamante of ISGlobal said, “Our results are new and interesting, but we do need to interpret them with some caution. Our study is designed to be collaborative and international; however, we need to study more diverse groups to fully understand this biology.”
The analysis drew on data from 11 cohort studies across multiple countries, including Spain, the Netherlands, Finland, France, Greece, Lithuania, Germany, South Africa, and the United States, as well as the United Kingdom. UK-based cohorts included the well-known Children of the 90s study in Bristol, the Born in Bradford study, and the Isle of Wight Birth Cohort.
Researchers collected detailed information on breastfeeding practices—whether infants were breastfed, for how long, and whether feeding was exclusive—through questionnaires administered from birth. DNA samples were then analyzed when the children were between 5 and 12 years of age. These were compared with samples taken at birth from umbilical cord blood, allowing scientists to distinguish changes that occurred after breastfeeding.
The consistency of the findings across diverse populations lends weight to the biological relevance of breastfeeding, even though the precise health implications of these epigenetic changes remain to be fully understood.
The study adds an important scientific dimension to long-standing recommendations on breastfeeding. Global health agencies, including the World Health Organization, advise exclusive breastfeeding for the first six months of life, followed by continued breastfeeding along with appropriate complementary foods.
Breastfeeding is already known to offer a wide range of benefits, from protecting infants against infections to supporting cognitive development and reducing the risk of chronic diseases later in life. It also provides health benefits for mothers, including lower risks of certain cancers and improved metabolic health.
At a time when changing lifestyles, urbanization, and workplace pressures are contributing to declining breastfeeding rates in many parts of the world, experts say such evidence underscores the need for stronger policy support. This includes maternity leave provisions, workplace accommodations, and community awareness programs that enable and encourage mothers to breastfeed.
In India, while nearly 95% of children are breastfed at some point, only 41.6% to 44.6% of infants are initiated within the crucial first hour of life, falling short of global standards. Although exclusive breastfeeding (EBF) for the first six months has improved to roughly 55–64%, high rates of premature top-feeding and poor counseling persist, contributing to 100,000 preventable child deaths annually, particularly among the poor, according to various reports.
Importantly, study researchers stress that breastfeeding decisions are often shaped by a range of social, medical, and personal factors, and that mothers should be supported rather than judged. The goal, they say, is to create an enabling environment where breastfeeding is both possible and sustainable.
