A New Way to Test for Food Allergies
A True Test for Allergies
Do you have food allergies? New research may have turned up a method of testing for true food allergies that is both non-invasive and more accurate than previous tests. This test relies on a new protein which may be responsible for causing allergic reactions to specific foods.
Food allergies are unlike inhalant or seasonal allergies. Tests performed on people who experience allergic reactions to certain foods show that some of them do not have the antibody IgE in their blood. (This is particularly true if the reaction to the allergen occurs some time after the substance is ingested.) As a result, such people would show a negative result on the standard allergy test, even when they are truly allergic.
A study conducted at Mount Sinai School of Medicine in New York looked at this new protein implicated in allergic reactions. The protein has been dubbed CD23, and is said to be located in the digestive tract. This protein acts as a receptor for IgE, which is the typical marker for allergies. Therefore, new information is arising to indicate that CD23 and IgE might be working together in allergic reactions to food.
A study was conducted on children ranging from age three to 17, who were asked to consume an allergenic trigger food - either milk or eggs. All of the test subjects had previously-known allergies to these foods and had shown positive results on other allergy tests. None of the subjects had experienced anaphylactic reactions; however they did have other symptoms such as skin reactions, breathing problems and gastrointestinal problems within two hours of eating the food. There were five control subjects who had no history of allergies.
The results of the study indicated that CD23 was detectable in the feces of food allergy patients, but did not show up in the feces of control subjects. This would imply that CD23 is either present in higher levels in those with food allergies or there is an in allergy-induced increase of CD23 in the stool. This opens an avenue for testing for food allergies which does not involve biopsies of the digestive tract or other invasive tests.
Based on the positive results in this study, researchers are interested in forming larger study groups to check how closely the presence of CD23 in stool corresponds to other clinical tests. The hope is that additional study could lead to more accurate allergy testing that is also more comfortable for patients.
Food allergies are more prevalent than you might think - of children younger than four; about six to eight percent have food allergies. Nearly two percent of all adults also have allergies. However, only a relatively small percentage of all these cases are considered “true” allergies, in that they are IgE mediated. The majority of people experience what would more accurately be called food intolerance.
July 22, 2006