Food allergies are common in babies and in the early childhood, but the probability of developing allergic reactions to food during breastfeeding remains unknown.

The first systematic review of the presence of food proteins in breast milk and the chances of developing IgE-mediated food allergies in babies has been done by a group of scientists from Sechenov University in collaboration with their colleagues from the UK, Norway, Canada, Germany, Australia, and the US. The paper titled Food Proteins in Human Breast Milk and Probability of IgE-Mediated Allergic Reaction in Children During Breastfeeding: A Systematic Review has been published in The Journal of Allergy and Clinical Immunology: In Practice.

Many mothers may report that their babies present symptoms such as vomiting, excessive crying, burping, and loose stools. Quite often in clinical practice, these symptoms are associated with IgE-mediated food allergy, connecting these effects with the presence of food proteins in breast milk. As a result, mothers may be forced to change their diets, and sometimes make the transition from breastfeeding to formula.

The authors of the paper reviewed 32 studies and compared the results with the data on the doses required to develop an allergic reaction, according to the Voluntary Incidental Trace Allergen Labelling, VITAL 3.0. It was found that in the vast majority of cases, the levels of food proteins in breast milk were much lower than the dose required to develop an IgE-mediated allergic reaction. The researchers estimate the probability of developing a reaction in a breastfed baby with IgE-mediated allergy as ≤ 1:1000 if the mother consumes cow’s milk, egg, peanut, and wheat.

“Our work is only the first step towards understanding a complex problem that has been of interest to scientists and clinicians for a very long time. The results of our study do not suggest that breastfed babies cannot have allergic reactions to the mother’s diet but show that the likelihood of this is much lower than commonly thought. This is extremely important, because an incorrect assessment of the reaction can lead to overdiagnosis of IgE-mediated food allergy,” said Daniel Munblit, Professor at the Department of Paediatrics and Childhood Infectious Diseases (Sechenov University) and head of the study.

“Now we have a weak evidence base and cannot say for sure what is the true cause of developing an IgE-mediated allergic reaction in breastfed babies. I hope that our study will initiate new randomised controlled trials that will give a more accurate picture of this issue,” said Aysylu Gamirova, a 6th year student of the International School Medicine of the Future at Sechenov University and the first author of the paper.