Babies who are exclusively breastfed for at least three months have markers in their blood that are different from babies who are not breastfed.
The findings come from the largest study of its kind conducted by an international consortium. The researchers studied data from blood samples in children, looking at epigenetic marks in the genome. Epigenetics refers to chemical changes in DNA that affect which genes are active and how they function. Specifically, the team looked at the epigenetic process of DNA methylation, a chemical process that can be detected in blood samples.
The research was led by the Barcelona Institute for Global Health (ISGlobal), the University of Exeter and the University of Bristol and published today. Clinical Epigenetics. The study found that DNA methylation marks on genes associated with immune and developmental processes were higher on average in children who were exclusively breastfed for at least three months, compared to children who were not breastfed.
However, the study did not look at whether these epigenetic marks resulted in any differences in the children’s immunity or development.
Our findings show that children who are exclusively breastfed have epigenetic changes associated with that experience. The genes affected by these markers are involved in developmental and immune processes, but we cannot say from our study whether it directly affects those highly complex processes. “
Dr Doretta Carmaschi, University of Exeter
Research has separately shown that breastfeeding is associated with short- and long-term beneficial effects on children’s health.
Dr. Mariona Bustamante of ISGlobal, an organization supported by the La Caixa Foundation, said: “Our results are new and interesting, but we 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 research was conducted through the Pregnancy and Childhood Epigenetics (PACE) Consortium, made up of 11 studies conducted internationally in mixed-ethnicity countries including Spain, the Netherlands, Finland, France, Greece, Lithuania, Germany, South Africa and the US. In the UK, studies included the Bristol-based Children of the 90s study, the Born in Bradford study and the Isle of Wight Birth Cohort study. The analysis included epigenetic data from 3,421 children in these studies.
The researchers looked at whether the babies were breastfed and for how long and whether they were exclusively breastfed and for how long. Information about breastfeeding since birth was collected through questionnaires. DNA methylation marks were measured from samples taken when the children were 5 to 12 years of age, and compared to samples taken from the umbilical cord to assess before breastfeeding. The researchers investigated whether there were any differences related to breastfeeding experience.
The study was published in Clinical Epigenetics With funding from a number of sources including the Medical Research Council, Wellcome and Horizon 2020.
Source:
Journal Reference:
Carmaschi, D., and others. (2026). Association of breastfeeding with DNA methylation in the Epigenetics of Pregnancy and Childhood (PACE) Consortium. Clinical Epigenetics. doi:10.1186/s13148-025-02042-4. https://link.springer.com/article/10.1186/s13148-025-02042-4.
