Donkey milk as a possible alternative for cow's milk allergic patients

Background: Previous studies have determined a high degree of similarity in the biochemical composition of human and donkey milk. Our objective was to determine the allergenic response to donkey milk in patients sensitized to cow’s milk attended during one year at our Allergy Department. Methods Samples of donkey milk were obtained from Zamora, Spain, and frozen at -72°C. In vivo (prick-prick and oral challenge test) and in vitro studies (specific IgE, SDS-PAGE and Western blot, and molecular analysis) were performed in four groups: two groups of patients sensitized to cow’s milk (severe clinical allergy and eosinophilic esophagitis) and two control groups (healthy and allergic to grass pollens without digestive symptoms), after informed consent. Results During one year, 2032 patients presented hypersensitivity to some food, of whom 83 exhibited severe symptoms related to cow’s milk intake (4%). Of these, 46 had positive IgE to alpha-lactoglobulin, 42 to beta-lactoglobulin and 47 to casein. Of these, 46 patients accepted donkey milk challenge, which was positive for 19. Of the 67 patients with eosinophilic esophagitis, 13 were challenged, being positive in 6 patients. The rest tolerated 100 ml of donkey milk without reactions. Western blot results showed an allergenic profile of donkey milk similar to that of cow milk in all patients analyzed, although clearly with less intensity in donkey milk. Conclusion We found a lower IgE-mediated allergic hypersensitivity to donkey milk in patients allergic to cow’s milk. Therefore, given its accessibility, donkey milk could be a feasible alternative for these patients.