The Basics of Food Allergy Testing

Food allergy testing is a commonly used diagnostic tool. It is regularly needed due to the increasing numbers of people who are either diagnosed with, or believe themselves to have, some sort of reaction to certain foodstuffs.

Doctors use various methods of skin testing, as well as blood tests to check for food allergies in both adults and children. Food allergy testing are carried out on children most often, if called upon. This is because the problem affects children moreso.


lab testing

How do doctors test for food allergies?

In certain circumstances, skin prick tests are used to diagnose allergies. In this, a little amount of a particular food extract is injected onto the surface of the skin. A swelling or redness will appear on the site of the injection due to an allergic reaction to that particular substance which had been tested. These tests are usually quick and cost less than the others.

A scratch test for food allergies is also commonly used. The testing procedure here involves a doctor or a professional healthcare supervisor scratching a particular area of the skin on the person’s forearm or back with a small amount of liquid extract of the substance in question. After waiting for fifteen minutes, if spots or redness is observed on the skin, it is an indication of a food allergy. In wheat allergy testing, eg for Celiac disease, a particular part of the person’s skin is pricked with wheat allergens.

Another method used by doctors for checking for food allergies is IgE testing, also known as RAST (radioallergosorbent) test. This entails a process where the doctor takes a small sample of the person’s blood and the sample is sent to the laboratory. The blood is examined for the presence of IgE antibodies to particular types of food. If there are a considerably large number of IgE antibodies present, it is an indication of the person being allergic to that substance. Wheat allergy tests can be carried out in the same manner to see if signs of the test point towards a this particular problem. Another blood diagnosis is by using the ELISA test method.

How accurate is allergy testing for foods? These blood tests are considered to be the best as there is less chance of getting any false results or contamination as one can get on the skin. But note that no test can give 100% accurate results. They must be taken in combination with previous history and/or food challenges to look for a reaction.

Allergy testing image via wikimedia

Allergy testing image via wikimedia



You can also self-test yourself to check for food allergies at home. All you need to do is gradually take increasing amounts of the particular item which you think you are allergic to. Meanwhile, you need to keep a constant check on observing the symptoms which appear. To double check, one can do an elimination diet to see if symptoms then reduce.

Online providers also claim to test accurately for problems. eg Alcat, Alletess, Metametrix.

Food allergy testing  does prove to be sufficiently accurate. However, tests for food intolerance and sensitivity do not always promise accurate results. Food intolerances are difficult to test. This is because people’s tolerance to specific ingredients can vary day to day.

There are two ways of food intolerance testing. One method is that of trial and error where the person must keep a constant written check on the specific diet he is having and at what times during the day. If any symptoms are observed, they should be recorded. The second method involves eliminating all foods which he suspects he has intolerance to, until all symptoms disappear. Then, the person should introduce those particular ingredients gradually again and meanwhile attribute the reaction to those particular foods and confirm the intolerance.


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