Allergy testing is equal parts detective work and lab science. In some cases, a clear determination of your allergens is possible through your own observations of when symptoms occur.
However, if treatment is to be effective, you must know your allergens accurately. Otherwise, a treatment approach could fail to work simply because you aren’t being treated for the right allergen.
If you suspect food allergies, one of the first and simplest things to do is to keep a food diary. Write down everything you eat, and also keep track of any symptoms you experience including how long it takes for your reaction to occur.
In fact, if food allergies are your problem, a simple way to check for problems (whether allergy or intolerance) is to take the food out of your diet for at least 4-6 weeks, and then reintroduce it. This is called the elimination diet and food challenge test. However, you must completely remove the offending food from your diet. This means becoming an expert in all the ways that a particular ingredient can hide in a prepared food.
While you are living without a particular food, be sure to replace necessary nutrients with other foods. After having lived without a particular food for a number of weeks, you will then reintroduce it. Any symptom should be much more obvious at this point.
While this approach will show foods that you “react” to, it will not absolutely confirm allergies. A true allergy involves the immune system and an IgE mediated response. While you may react to a food, if the reaction is caused by a different mechanism, it is not an allergy.
If you don’t have a clear indication of what is causing your allergies (or even if what you have is a true allergy), the next step is an allergy test. The most common allergy test that your doctor will suggest is a ‘prick test’. This test uses a small drop of the allergen on the skin. A needle is poked through the drop to introduce a small amount of the allergen extract into the body. The theory is that if you have an allergy to the substance, you will have a reaction at that location. Test results are available quickly: you’ll normally know which things you have reacted to within 15 minutes.
Another option is the intradermal test. In this case, a tiny amount of allergen is actually injected under the skin. This is a more sensitive type of allergy testing and may be used when the prick test indicates a negative and yet the person is still having symptoms.
Your allergist or immunologist can also suggest a RAST test. This is a blood test. In general, the draw back of this test is that results take much longer to be available. In most cases, your doctor will not suggest a RAST test unless you are unable to tolerate either prick tests or intradermal tests or if you are taking certain medications that could interfere with the results.
A test performed by many alternative medical practitioners is the electrodermal test. This type of test can be done with a variety of technologies – all very similar – but one of the most common ones is the Vegatest. While much anecdotal information from the alternative medical community points to good results with this technology, the only existing double blind tests of the Vegatest against conventional prick tests are contradictory. Some studies show that Vegatest is unreliable; some studies show that Vegatest can accurately identify allergens. This leaves the medical consumer with a question that will most often be posed to a doctor. At issue for most conventional medical doctors is the premise by which Vegatest operates, which is that it is possible to identify allergens through a change in whole body electrical conductivity.
Keep in mind that Vegatest is not looking for IgE, but is looking for a problematic response to a substance. Conventional medical allergy testing is very specific; if you don’t have an immune system response mediated by IgE, it’s not going to find it. In fact, even conventional testing can miss allergies, which is why there are multiple types of tests. So, it is possible that Vegatest is not comparable to true allergy testing because testing for IgE mediated allergy and Vegatest are actually doing two different things.
When it comes to any allergy testing, it is advisable that you research the process and understand the reliability of the test. Ask questions about any test that you will be undergoing.
Managing allergies is all about taking responsibility for your own health; it is a chronic condition that is more about what you do outside the doctor’s office than what your doctor does within it. Testing is just one aspect of managing your allergies.