The largest study of its kind has revealed that babies who are breastfed (without the addition of any other food) for at least 3 months have markers in their blood that are different from babies who are not breastfed.
These markers are known as "epigenetic" markers, which are chemical changes that occur in DNA and affect gene activity and how they work.
Specifically, the researchers focused on a process called "DNA methylation," a chemical process that can be easily detected in blood samples.
The study was conducted through an international consortium of 11 studies from 9 countries, led by the Barcelona Institute for Global Health in collaboration with the Universities of Exeter and Bristol.
Markers linked to immunity and development... but without proof of a direct effect
Researchers found that methylation markers on genes associated with immunity and development were, on average, higher in infants who were exclusively breastfed for at least three months compared to those who were not. However, the study did not investigate whether these markers actually led to differences in the children's immunity or their physical or mental development.
Dr. Dorita Karamski, co-leader of the study from the University of Exeter, said: "Our results show that babies who are exclusively breastfed carry 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 this directly affects these complex processes."
She noted that other separate research has already proven that breastfeeding is associated with short- and long-term health benefits for the child.
Dr. Mariona Bustamante from the Barcelona Institute for Global Health added: "Our results are new and interesting, but we need to interpret them with caution. Our study was designed to be collaborative and international, but we need to study more diverse groups (including different races and backgrounds) to fully understand this biology."
The research was conducted by the PACE consortium, which specializes in studying epigenetic markers in childhood and pregnancy. The consortium comprised 11 studies from multiple countries: Spain, the Netherlands, Finland, France, Greece, Lithuania, Germany, South Africa, and the United States (including a mixed-race cohort). Researchers analyzed data from 3,421 children across these combined studies.
Breastfeeding information was collected through questionnaires that tracked children from birth, recording whether they had been breastfed, for how long, and whether breastfeeding was exclusive.
To measure epigenetic markers, blood samples were taken from children between the ages of 5 and 12, and then compared to samples taken from the umbilical cord at birth (to assess the situation before breastfeeding began). In this way, researchers were able to isolate changes associated with the breastfeeding experience itself.
The results were published in the journal Clinical Epigenetics.
