A recent article in the was written by a Toronto doctor who warns that some food allergy tests can be misused or misinterpreted. According to the Dr. Elana Lavine cautions that food allergen test results can be misinterpreted to mean that the patient has an intolerance to a food, when in fact this is not the case.
Canadian Medical Association Journal
According to Dr. Lavine, blood testing used to diagnose adverse reactions to food typically looks for antibodies known as IgG. However, there is no proven link between IgG and food allergy diagnosis. As a result, it is possible to have a 'false positive' (IgG antibodies but no symptoms when the food is consumed) or a false negative (symptoms tied to a certain food, but no IgG antibodies found during the allergy test).
In addition, the doctor points out, there is a significant difference between having an intolerance for a particular food and having a true food allergy, which often comes with more serious side effects. However, most commonly used food allergen tests cannot detect a food intolerance, or consider all negative reactions to be the same magnitude, creating confusion about whether the person is allergic and how serious their allergy may be.