Elimination Diets And Food Challenges - Pinpointing Your Allergic Triggers: Allergies

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Elimination diets and food challenges

Elimination diets and food challenges

Because of the complex array of ingredients in the foods we eat, diagnosing food allergies can be tricky. In some instances, the nature and severity of the reaction, combined with a positive blood test or skin test, make the diagnosis obvious. For some foods, investigators have been able to define levels of specific IgE in the blood by the size of the reaction on the skin to help predict if a food is causing allergic symptoms. However, this is not always the case, and other approaches are needed.

Elimination diets. One way to see if a food is causing your allergies or making them worse (for example, if you suspect that dairy or eggs are triggering your child’s eczema) is to eliminate that food from the diet for a period of one to two weeks. Depending on the food in question, this may not be as easy as it seems. For example, eggs and milk are found in many common foods, such as breads and frozen dinners. And components of eggs and milk sometimes go by names that are not as easily recognizable, such as lactalbumin, casein, or whey, in the case of milk. If avoiding the food brings relief, you can cautiously reintroduce the food to see if symptoms worsen. Even then, diagnosis may not be certain.

Food challenge. The gold standard for diagnosing food allergy in these circumstances is a double-blind placebo-controlled food challenge (DBPCFC). In this test, the doctor asks the pharmacy to make up solutions or capsules containing either the suspected food or an inert placebo. Each is then administered to the patient in random order — then you wait to see what happens. To ensure an objective assessment, neither the doctor nor the patient knows what is being given.

Elimination diets, rechallenging after an elimination diet, and challenge testing of any sort should only be done under strict medical supervision by those experienced in the techniques.

Last updated:	August 21, 2006
Reviewed By:	Faculty of Harvard Medical School