Traditionally, food allergy is diagnosed using a patient's history in combination with either skin prick testing with standard allergen reagents or specific immunoglobulin E (IgE) estimation from a blood serum sample. However, oral food challenge is the gold standard. 

A major advance in the diagnosis of food allergy has been the development of tests which can measure whether individual food proteins are involved in allergic reactions. For example, peanuts have 13 or more allergens (proteins) we know about, and some of them are involved in a primary allergy to peanuts and some in cross-reacting food allergies. Assessing whether someone has antibodies against a particular protein in a food can help a great deal with diagnosis. This is especially important when trying to assess whether someone has a primary allergy to peanuts and needs to avoid even traces of them in foods; or whether their allergic symptoms are caused by antibodies to pollens, such as trees or grass, cross-reacting to peanuts because the proteins are very similar. 

If the allergy is due to a cross-reaction, then the chance of a severe reaction is much lower, and there is no need to avoid foods containing traces of peanuts. This technology is a recent innovation and is not often available, except in specialised allergy clinics. This Trust has been using such technology in food allergy diagnosis for the last five years and the allergy team has considerable expertise in interpreting the results.