Food Allergies

Up to 2 million, or 8%, of children, and 2% of adults in the United States are estimated to have food allergies.

With a true food allergy, an individual's immune system will overreact to an ordinarily harmless food. This is caused by an allergic antibody called IgE (Immunoglobulin E), which is found in people with allergies. This antibody may develop after eating the food repeatedly in the past but without having problems. Food allergy may appear more often in someone who has family members with allergies, and symptoms may occur after that allergic individual consumes even a tiny amount of the food.

Food intolerance is sometimes confused with food allergy. Food intolerance refers to an abnormal response to a food or food additive that is not an allergic reaction. It differs from an allergy in that it does not involve the immune system. For instance, an individual may have uncomfortable abdominal symptoms after consuming milk. This reaction is most likely caused by a milk sugar (lactose) intolerance, in which the individual lacks the enzymes to break down milk sugar for proper digestion. Your allergist can help you determine the difference between intolerance and allergy and help you in establishing a management plan.

The most common food allergens are the proteins in cow's milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

Diagnosis

An allergist/immunologist is the best qualified professional to diagnose food allergy. Diagnosis requires a carefully organized and detailed assessment ofthe problem. First, the allergist/ immunologist will take a thorough medical history, followed by a physical examination. The allergist will inquire about detailed contents ofthe foods, the ftequency, seasonality, severity and nature of the symptoms, and will ask about the amount of time that elapses between eating a food and any reaction.

Allergy skin tests may be helpful to determine which foods, if any, are triggering a patient's allergic symptoms. In skin testing, a small amount of liquid extract made from the food is placed on the back or arm. In a test called a prick test, a needle is then passed through the liquid on the top layer of the skin. In some cases fresh foods may be needed for skin testing.