Diagnosing Food Allergies with Component Testing

Nearly 6 million kids in the U.S. have food allergies, and this number has been on the rise in the last two decades. When a child has an allergic reaction to food for the first time, our allergy team recommends allergy testing. It’s important to identify what’s causing the allergic reaction, so the culprit food can be removed from the diet and to prevent unnecessary removal of many foods from the diet.

Ideally, the next steps are a visit with an allergist, allergy testing, and a plan for specific food avoidance. A variety of tests can be used, along with a good history of the allergic reaction, to aid in diagnosing food allergy. Commonly used tests include skin prick testing, specific IgE blood testing, and oral food challenges, which should only be performed by an experienced allergist at a medical facility. Allergy component testing is another type of food allergy testing that pinpoints specific proteins that may be causing allergic symptoms. It’s a newer test mostly used in research settings, but it’s also available for use in patient care.

Most research with allergy component testing has been done using peanut components (specific peanut proteins). This type of testing can be useful for estimating a patient’s level of risk for allergic reaction. For example, certain components are more associated with risk of severe allergic reaction to peanut than others. An allergist could use these results to help with deciding whether or not someone should avoid peanuts altogether or perform an oral food challenge. An even newer method of testing component levels is by ISAC testing, which uses such a small amount of blood that it can be taken by a finger prick.

Overall, a good history of the allergic reaction is the best tool for evaluating food allergy. Combined with focused skin prick or blood testing, this patient history is often enough for an allergist to make an informed decision about food allergy diagnosis. But allergy component testing is also a helpful tool that may contribute more to clinical food allergy diagnosis and treatment in the years to come.