The diagnostic strategies to test for food allergies include; skin prick testing, antibody blood testing, elimination diets, and oral food challenges.
Skin prick tests are conducted by evaluating an individuals reaction to a prepared food extract as it is introduced to their blood via the skin. If the suspected allergen causes the skin to redden larger than 3 mm in diameter, it’s considered a positive result. Although, positive results are only correct in suspecting the allergy less than fifty percent of the time.
Antibody blood tests can determine the allergy of a substance if an individual has higher than normal rated of the antibody for the suspected allergen.
An elimination diet can be used in order to identify an allergen by evaluating whether or not the symptoms of the allergy subside. This can happen after the suspected allergen is taken out of the diet. If the symptoms decrease or disappear then the allergen has been identified.
Oral food challenges are the most complicated of these tests. The suspected allergen is added to a food and eaten by the individual. If there’s no reaction, there’s a false-negative result. These are usually performed as a double-blind experiment wherein the examiner and subject do not know whether the food contains the allergen or a placebo.