Humans are allergic to a variety of environmental factors, including dust mites, animal dander, plants, ragweed, pollen and mold. We are also allergic to things we eat. It is estimated that allergies to food affect up to 12 million Americans.
Before a food allergy can be treated, it must be determined that it is a true allergy to food (ie, an adverse immune response to a food protein) and not food intolerance. The two are often confused because they can elicit the same signs and symptoms from the sufferer.
A food intolerance does not involve the immune system, and usually a person can consume small amounts of a food without having anything more than a mild reaction. Two common conditions that are sometimes mistaken for food allergies are lactose intolerance and irritable bowel syndrome. These two conditions are chronic and cause gastrointestinal discomfort, such as cramping, bloating, excess gas, and diarrhea and/or constipation. Patients who are lactose intolerant lack an enzyme that is necessary to fully digest food. IBS is a diagnosis of exclusion, and a variety of tests must be done to confirm that the gastrointestinal upset isn’t due to a more serious underlying illness like cancer.
Food allergies, in addition to causing the previously mentioned gastrointestinal symptoms, also cause swelling of the lips, face, throat and tongue, tingling mouth, difficulty breathing, dizziness, fainting, nausea and vomiting. Food allergies and food intolerance, therefore, share a cascade of symptoms and tests must be performed to confirm a true allergy.
The following tests are used to diagnose food allergies:
- Skin prick testing.
- Blood tests (the RadioAllergoSorbent Test [RAST] for one).
- Food challenges.
Skin prick testing is just how it sounds. A small amount of an allergen is placed on the skin or into a testing device and the skin is “pricked” or broken through so that the allergen is deposited under the skin. Results, if there are any, appear quickly. If a person is allergic, a hive or bump will form within minutes. With the RAST blood test, the presence of IgE antibodies to a specific allergen can be detected. For food challenge testing, the patient is given a capsule containing the suspected allergen, and then observed for any allergic reaction.
Allergies to food usually involve “wheat, peanuts, eggs, dairy, shellfish, seafood, tree nuts, and soy, otherwise known as “the big 8,” and account for approximately 90% of food allergies in the United States. These foods are so pervasive in the American diet that precautions must be taken by those who have severe reactions such as anaphylactic shock. The symptoms of this most extreme allergic reaction include dizziness, difficulty breathing, loss of consciousness, swelling of the tongue, low blood pressure, heart failure, and even death. Immediate treatment is necessary for this kind of shock.
Treatment for food allergies usually consists of avoiding the food. In some instances an allergic person is so sensitive that any kind of exposure to the allergen must be avoided, including inhalation of or touching the food or even touching any surfaces that might have come in contact with the food. Some foods are easier to avoid than others. Shellfish, for example, is not usually found in fast food establishments. Other foods however like wheat and peanuts are added to bread, crackers, cereals and oils. Their presence is not so obvious. For this reason people diagnosed with a severe food allergy should carry an autoinjector of epinephrine (ie, EpiPen) and medical alert jewelry so that if they are exposed to an allergen, they can be treated immediately.