Food Intolerance Testing - What You Can Expect

It is often the case that diagnosis of a food intolerance is possible. Many food intolerance symptoms can also be caused by other conditions and it may take some time before the intolerant food is identified by food intolerance testing and your doctor can confirm that you have an intolerance.

If you have an allergic reaction after consuming some food you should think about the following issues and bring the answers to your doctors attention:

* How soon did the reaction start?
* Did you take any treatments (eg antihistamines) and did it work?
* Do you always get this reaction to the food?
* How much did you eat?
* Did anybody else eating the food get ill?
* Do you have a family history of eczema, asthma, hay fever or food intolerance?

Elimination diets and challenge diets - you may be asked to remove the suspected intolerance food from your diet and replace it with a different food. If your symptoms improve, a diagnosis may be offered.

To confirm this diagnosis, your doctor may then ask you to re-introduce the food back into your diet.

In skin prick food intolerance testing, an extract of the suspect food is applied to the skin and a fine scratch is made. If redness and swelling develops around the scratch, the test is positive for that food. Typically an array of scratches will be made on the forearm or back and a different foodstuff applied to each scratch.

However this test suffers from false positives. It is often the case that full diagnosis of a food intolerance is possible. Many food intolerance symptoms can also be caused by a number of other conditions and it may take some time before the intolerance food is identified by food intolerance testing and your doctor can confirm that you have an intolerance.

Blood tests (RAST) tend to be most useful for those who have a severe food intolerance and are at risk of anaphylaxis or who have eczema or dermatitis and can't have a skin test. The RAST test measures levels of food-specific antibodies in your blood. This test can result in false positive results (as in skin prick tests), or in false negative results (when your body produces antibodies but they aren't circulated in the blood).

The newer RAST tests are called ImmunoCAP RAST tests and measure specific IgE antibodies to particular food allergens. To simplify matters, there are various screening processes that can be used. In total there are up to 160 different food allergens available for investigation by this method. It is sometimes the case that full diagnosis of a food intolerance is not straightforward. Many food intolerance symptoms can also be caused by a number of other conditions and it may take some time before the problem food is identified by food intolerance testing and your doctor can confirm that you have an intolerance.