Allergies & Sensitivities Testing Methods
Elimination and reintroduction
Eliminating and later reintroducing a potential allergen in the diet is the most reliable way to test it. The method is to eliminate a suspected allergen from the diet for a 1-3 weeks until the symptoms decrease or go away entirely. Then reintroduce with a minimum of 3 servings daily for at least 3 days.
The theory is that your sensitivity to the potential allergen increases when you stop consuming it, and when the food is reintroduced, the symptom may be more noticeable. This method is fairly accurate at demonstrating which foods cause problems for you. You'll need to be very patient and pay close attention to symptoms. It is helpful to rate your symptoms before you begin, after removing the food, and after reintroduction, on a scale of 1 to 10.
It's a good idea to do this with the assistance of a medical professional who monitors your diet. Rarely, reintroduction of an food that is an allergen can induce dangerous reactions in some people, particularly people with asthma. This is another reason to try this method only with supervision.
In scratch or prick testing introduces the potential allergen to the skin with a sterilized needle. After some time, which varies - from minutes to several days, any reactions are noted. If there is a reaction, such as a rash, hives, etc. then this is considered a positive result. This method can be inaccurate however, often yielding a false positive.
Tests that examine immunoglobulins
These tests, RAST (radioallergosorbent test), MAST, PRIST, ELISA, etc examine antibodies in the blood which are known to react to very specific foods. RAST is frequently used and is found to be fairly accurate.143, 144 but it doesn't help identify sensitivities, rather than allergies, to food so there are often false negatives. Adjustments have been made to the test (MAST, PRIST, ELISA) which appear to reduce the chances of false negatives, but sometimes yield more false positivess. There are many health conditions that have been found to be tied to food sensitities, including irritable bowel syndrome and migraine headache - which are poorly identified from RAST testing.
In this test, a microscope is used to look at the person's blood serum to look for reactions to certain substances. It is inaccurate and is not considered to be reliable. 145
(provocation-neutralization; end-point titration)
This controversial method use injections under the skin of tiny diluted foods or other materials in the environment. Depending on the result, additional diluted portions are added. The method theorizes that one strength of dilution can cause a reaction while another may not, or may neutralize the reaction. The approach may have helpful effects. 146, 147 Similarly, these material dilutions can be tested under the tongue, but double-blind research has not substantiated the effecacy. 149
Other controversal methods try to measure electrical activity changes at acupuncture points when a possible allergen is nearby. One study reported that this method (EAV - Electroacupuncture According to Voll, or VEGA test) identified identical allergens as RAST testing 70.5% of the time. Another study found the Vega test to yield identical results 66% to clinical ecology testing.
Source. J.C. Breneman, Basics of Food Allergy. Springfield, IL: Charles C Thomas, 1978, 45-53.