The ELISA (Enzyme-Linked Immunosorbent Assay) test is used to try to identify foods which may be causing IBS symptoms. The patient uses a small 'lancet' to prick their fingertip, and they then collect the blood into a small vial. This is done in the home. The patient then sends the sample away to a laboratory for analysis.
At the lab, the sample is tested to see how it reacts with various different foods. Specifically, the level of what are called 'IgG antibodies' are measured, and if particularly high levels of IgG antibodies are found when testing a certain food, it means that the patient is reacting against that food and should probably try to avoid it.
The patient then receives a report which details the reaction levels to different foods. For tests offered by York Tests, the results will show as +1, +2, +3 or +4, depending on the level of antibodies found. For tests offered by Cambridge Nutritional Science, the levels will be on a scale of 0 to around 130. If a patient is found to have a strong reaction to certain foods they will be advised to avoid these foods completely. There may also be other foods which cause a lesser but still significant reaction, and the patient may be advised to only eat these foods a few times a week.
The ELISA test is offered by several different companies including York Test and Cambridge Nutritional Science.
How successful is this test in clinical studies?
In 2004 a study published in the journal Gut (Atkinson W et al) looked at 150 IBS patients. Patients followed either a diet based on the results of an ELISA test, or a 'sham' diet which excluded some foods, but not those to which they had had significant reactions. These diets were continued for three months.
Patients who followed the ELISA-based diet reduced their symptoms by 26%. Overall there was a 10% greater reduction in symptoms in the ELISA diet group than in the sham diet group. The ELISA group also reported more problems with returning symptoms if they ate foods that they were supposed to be avoiding.
I have/had IBS very severely. I tested with the ELISA test on my own and found nine sensitivities. Not all, I felt, I had reactions to, but one of the sensitivities came through as wheat. Not gluten, but the wheat itself. I can have breads/products with gluten with no problem. However, by eliminating wheat-flour products I found a 97% change. Please note, I have IBS as soon as I go and start to eat wheat products. Luckily, there are other flour products out there to substitute with. Whole food stores, Wild Oats etc have lots of items and baked items to choose from. You're not really giving up any foods, but just re-selecting brands.
I think people with IBS overlook this test and I did this on my own without the advise of a physician. Heck, they just told me to live with it...don't think so! Something is causing me to hit the bathroom 15 times a day...if I make it!