Evaluation of the presence of bovine proteins in human milk as a possible cause of allergic symptoms in breast-fed children

Background: It is generally believed that the elimination of certain foods from the diet of mothers during the lactation period produces a significant improvement in breast-fed children who develop allergic symptoms. Several studies have shown the presence of food proteins in human milk; on the other hand, no study has been able to correlate unequivocally the presence of these allergens in human milk with newborn sensitization. Objective: The aim of this study was to evaluate the presence of bovine proteins in breast milk. Methods: Milk samples were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). To detect bovine proteins in human milk, immunoblotting was performed by using monoclonal antibodies (MA) specific for β-lactoglobulin and bovine caseins. Results: The results of this study do not confirm the presence of bovine proteins in breast milk suggested by other authors and shows unequivocally that the conflicting results reported in the literature about the presence of β-lactoglobulin in human milk are due to cross-reactivity between bovine milk proteins and human proteins. Conclusions: Components other than bovine β-lactoglobulin or caseins could be involved in the induction of allergic symptoms in exclusively breast-fed children.