The invention relates to novel compositions and methods for diagnosing or treating food allergies. The invention particularly discloses new approaches for delivering food allergens to allergic patients by oral administration of formulations which dissolve and release proteins in the stomach. The invention allows the treatment of food allergies by delivering food allergens to the gut immune system with controlled exposure of the esophagus or oral cavity. The invention also allows to perform food challenges to assess the threshold of clinical reactivity without exposing the esophagus and oral cavity. The invention may be used in any subject, particularly human subjects, and is applicable to any food allergen.