IGHE and food allergy: To date, two different routes for initiation of IgE-mediated true food allergies have been described: 1) primary oral sensitization through food intake, or 2) secondary cross-reaction, in which the patient is sensitized against inhalative allergens (e.g., pollens) and produces IgE-antibodies that react to homologous proteins in food (like nuts, apples, and carrots).