Exclusive breastfeeding linked to long-term changes in blood markers

The finding comes from the largest study of its kind, conducted across an international consortium. Researchers studied blood sample data in children, looking at epigenetic marks across the genome. Epigenetics refers to chemical changes to DNA which influence which genes are active in blood cells. This, in turn, can be measured through which biomarkers are present in the blood.

The study was led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the ”la Caixa” Foundation, in collaboration with the University of Exeter and the University of Bristol and published in Clinical Epigenetics. The team found blood biomarkers associated with immunity and developmental processes in children who had been exclusively breastfed for at least three months. These markers were not present in babies who were not breastfed. However, the study did not look at whether the children had any difference in their immunity or development as a result of carrying these biomarkers.

Study co-lead Dr Doretta Caramaschi, of the University of Exeter, said: “Our findings show that babies who are exclusively breastfed carry markers in the blood related to that experience. The genes that produce these markers are related to developmental and immunity processes, but we can’t say from our study whether this affects those highly complex processes directly. “

Other research has shown separately that breastfeeding is associated with short- and long-term beneficial effects on child health.

Dr Mariona Bustamante, researcher at ISGlobal, added: “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 research was conducted via the Pregnancy and Childhood Epigenetics (PACE) Consortium, made of 11 studies internationally, in countries including Spain, the Netherlands, Finland, France, Greece, Lithuania, Germany, South Africa and US, including a cohort of mixed ethnicity. In the UK, the study involved the Bristol-based Children of the 90s study, the Born in Bradford study and the Isle of Wight Birth Cohort Study. The analysis incorporated blood sample data from 3,421 children across these studies, aged 5 to 12 years when samples were taken.

Researchers looked at whether they were breastfed and for how long, and whether they were exclusively breastfed, and for how long. Information on breastfeeding was collected through questionnaires from birth. Blood samples were taken when the children were aged between five and 12 years old. They then measured epigenetic blood biomarkers and tested whether there was any difference related to the experience of being breastfed.

Published in Clinical Epigenetics with funding form multiple sources including the Medical Research Council, Wellcome, and Horizon 2020.

Reference
Caramaschi, D., Fernández-Barrés, S., Casey, E., Cruells, A., Czamara, D., Sharkawy, M. E., Elliott, H. R., Fore, R., Gairola, R., Gruzieva, O., Huels, A., Lahti, J., Lee, H., Magnano San Lio, R., Malmberg, A., Mansell, T., Merid, S. K., Novakovic, B., Ott, R., … Bustamante, M. (2026). Breastfeeding association with DNA methylation in the pregnancy and childhood epigenetics (PACE) consortium. Clinical Epigenetics. https://doi.org/10.1186/s13148-025-02042-4