Allergy Testing
Many people ask how they can be tested for allergies. The answer is there is no simple test. Let me explain.
If you need to test for inhaled allergies such as for pollen or house dust mite then you can use prick tests on the skin and these are quite accurate and are sometimes available in hospital departments. However prick tests are unreliable for food allergies.
For food allergies or more strictly speaking for food intolerances, the gold standard test is the exclusion diet, also called the elimination diet. This involves stopping the suspected food for 1 – 2 weeks and then re-introducing the foods to see if there is a reaction. There are several versions of this diet. The most commonly used is the stone age diet which involves eating only meat, fish, fruit, vegetables and water for one week (see food intolerance leaflet).
Though elimination diets are very useful the test can be tedious and time-consuming, so people have looked for simpler methods. Blood tests have been used. These include the RAST test which is often done in hospitals. Unfortunately this will only pick out fairly severe allergies (not intolerances), such as those to to nuts and fish, but will miss the majority of cases of food intolerance. It has only a limited use.
Other blood tests are available privately. These are not perfect but still useful. These include microarray ELISA tests, the ALCAT test , the YORK TEST and Cyrex array 10. They are about 70% accurate which is useful given the difficulties of diagnosis. They come with a kit that allows you to take a small blood sample and post it to the laboratory. In my opinion these tests often find a lot of food allergies and staying of all these food can be difficult and sometimes unnecessary so re-introducing the foods after an interval to check if they are really causing trouble may still be required.
These test about 100 or more foods and can be a useful guide but are expensive.
Other methods sometimes used for testing allergies include Vega testing which involves measuring the electrical potential on an acupuncture point while you are in contact with the food, and kinesiology, which involves testing the strength of a particular muscle while you are in contact with a food. These methods are controversial but can have a role to play. The accuracy will vary with the skill of the practitioner. However the results should be regarded as only a guide to allergies. The suspected foods can then be removed and reintroduced as in an exclusion diet to see if they are relevant.
