There are two main ways that a food can cause bother-some physical symptoms. The first category is what we call a food hypersensitivity. These reactions occur when your immune system responds abnormally to proteins in specific foods. These immunologic reactions may be caused by IgE antibodies, which we refer to as a food allergy, or may be related to mechanisms that do not involve IgE.
Patients with food allergy due to IgE antibod-ies often have gastrointestinal symptoms (nausea, vom-iting, diarrhea, and abdominal cramping), skin reactions (hives and eczema), and full-blown systemic reactions, also called “anaphylaxis” (throat swelling, wheezing, and drop in blood pressure). Food hypersensitivity that is not related to IgE antibodies includes a number of rel-atively rare disorders, such as food-induced enterocolitis (inflammation of the colon) and celiac disease (immune reaction to gluten).
The second large category of reactions is referred to as food intolerance reactions. These adverse responses to foods are relatively common and are not related to any immunologic mechanism. A good example is lactose intolerance.