A food challenge test is a variation on the elimination diet that also helps a physician to diagnose food allergies in a patient. During this test, a suspect allergen is deliberately introduced to the patient in a controlled environment. The patient consumes the food in pill form or disguised in a meal, and then is monitored for a reaction.

To further boost the odds of an accurate diagnosis during a food challenge test, a double-blind study is often conducted. In this approach, the food being tested is disguised to look the same as a placebo (an inert substance). Neither the patient nor the tester knows when the suspected allergen has been introduced. A third party monitor keeps track of whether the actual food or a placebo has been administered.

Food challenge tests are not routinely performed, and should only be conducted under the close supervision of a licensed medical professional. In rare cases, these tests can provoke anaphylactic shock, a life–threatening whole-body allergic reaction.

In recent years, alternative allergy tests have become increasingly popular—and controversial—methods used to “diagnose” allergies. Most healthcare experts are highly skeptical of these methods, saying there is little proof of their accuracy. Two alternative tests are used to diagnose food allergies:

• Cytotoxic testing. A blood test that supposedly identifies food or inhalant allergies. However, a number of clinic trials have found these tests completely ineffective at diagnosing allergies, according to the American Academy of Allergy, Asthma and Immunology (AAAAI). Such testing is therefore not recommended.
  
  
• Sublingual provocation and neutralization therapy. A combination therapy that supposedly identifies the allergen triggering allergy symptoms and then increases the patient’s tolerance of that allergen. It is unproven and not recommended by the AAAAI. The practitioner takes neutralizing substances—such as extracts of allergens, chemicals and foods—and injects them into the body or places them as drops under the tongue. Dosages are increased until the patient has a reaction. Once a reaction occurs, an allergy is diagnosed, regardless of whether or not an immune system response is involved. Additional doses of the allergen are then administered to “neutralize” the reaction.