If you react in some way to a food, it may be a food allergy or intolerance. Food allergies are increasing and may be due to the general increase in allergic disorders, but also may be due to some environmental or dietary factors we have yet to determine. Many patients who have been screened by other doctors and given a diagnosis of irritable bowel syndrome after other diseases have been ruled out, actually turn out to have food allergy as a cause of their symptoms.
We can help you determine whether your skin or gastrointestinal symptoms are due to allergy to one or more foods. A diagnosis of food allergy requires evidence that the allergic part of the immune system has been activated (sensitization) in conjunction with actual symptoms that relate to exposure to that particular food (true food allergy when both criteria are met).
The gold standard for determining a food allergy is a physician-supervised oral challenge (eating the food in gradually increasing amounts under observation). Food challenges are not always safe or practical. Reliable testing may be performed by your allergist by skin prick testing, atopy patch testing for food, and blood IgE testing (ImmunoCap method) for specific foods.
Food allergies may be divided into two general groups: immediate-type (due to preformed antibodies called immunoglobulin E, or IgE for short) and non IgE-mediated, generally due to delayed-type hypersensitivity, due to the action of the cellular part of the immune system. Some examples of immediate-type food allergy include hives or swelling (urticaria or angioedema), oral allergy syndrome, allergic gastroenteritis, and even nasal or chest symptoms due to food, and in severe cases life-threatening reactions such as anaphylaxis. Delayed-type hypersensitivity can cause abdominal pains and constipation, or even diarrhea. Some conditions such as allergic gastroenteritis in the form of the food-protein induced enterocolitis syndrome are non-IgE mediated and felt to be a result of cell-mediated immunity. Food allergies that are mixed include food-induced eczema or eosinophilic esophagitis. These disorders have features of immediate-type and delayed-type hypersensitivity to foods.
Celiac disease is an immunologic, mainly gastrointestinal disorder (diarrhea, malabsorption, weight loss) than can have extra-intestinal features (skin rashes, joint pains, fatigue, etc). It is felt to be a result of immune-activation and damage to the intestines from immune activity directed against gluten, the wheat protein complex also found in other grains such as barley and rye. Celiac disease can be screened for by blood testing but definitive testing may require colonoscopy under the care of a gastroenterologist.
From the AAAAI: There are methods of allergy testing that the American Academy of Allergy, Asthma & Immunology (AAAAI) believes are not useful, effective or may lead to inappropriate diagnosis and treatment. These include: allergy screening tests done in supermarkets or drug stores, home testing, applied kinesiology (allergy testing by testing muscle strength or weakness), cytotoxicity testing for food allergy, Rinkel skin titration method, provocative neutralization testing, Immunoglobulin G (IgG) testing for food allergy or sublingual provocation.
