What is a controlled food challenge?
In a controlled environment such as an allergist’s office, the doctor (usually a board-certified allergist) may conduct a food challenge test to determine if a food allergy exists, to confirm a suspected food allergy, or to see if a person has outgrown a food allergy.
Samples of the suspected offending food may be eaten on its own or mixed with another food. Sometimes the food may be disguised in a capsule. These food preparation techniques are used to prevent undue influence on the outcome of the test (if the person recognizes the food by sight or taste).
You eat the food or take the capsule under strict supervision. After eating the food or taking the capsule, you will be monitored to see if a reaction occurs.
Most food challenges are done as an open challenge where both the patient and physician know what is being eaten.
The ideal way to perform the food challenge test is as a "double-blind, placebo-controlled test." With this method, neither the allergist nor the patient is aware of which capsule, or food, contains the suspected allergen. In order for the test to be effective, you must also take capsules or eat food that does not contain the allergen. This will help the allergist make sure the reaction, if any, being observed is due to the allergen and not some other factor.
Someone with a history of severe reactions cannot participate in a food challenge test unless it is being done to see if the person has outgrown the food allergy. Only one food can be challenged at one time.
Food challenges are the only way to confirm or deny if someone is allergic to a food or not. Skin and blood allergy testing is not definitive because it can have many false positives, and false negatives are possible. Food challenges are safe ways to know if you can safely reintroduce a food or if you need to continue to avoid a food.