Q: My son is 16, with multiple food allergies since he was a toddler. Over the years, he’s had four experiences with anaphylaxis, but food errors have mostly been confined to mild reactions. As his reactions vary, my question is: If my son ever passed an oral food challenge, how would he know if this was a reliable result – and not just a good immune system day?
Dr. Sicherer: One reason reaction severity may vary has to do with the amount of the allergen consumed.
For example, a person may have mild or even no symptoms with eating one peanut, but have severe symptoms if 15 peanuts are eaten.
The oral food challenge is a test that actually takes advantage of the quantity issue by starting with very small amounts of the suspect food and gradually increasing to larger amounts. In this way, if there is an allergy, the person will not have eaten a large amount right from the start. The feeding can be stopped at the first sign of a clear reaction.
Meal-Sized Amount Helps Confirm
Food challenges typically aim for at least a meal-sized amount of the food so that when the procedure is completed without any symptoms, it is unlikely that future consumption would lead to a problem. Still, roughly 3 percent of the time, people experience symptoms (usually mild) despite tolerating the oral food challenge.
No test is perfect and this may be related to what you describe as a “good immune system day.” Sometimes eating much more of the food, or having an illness, drinking alcohol, exercising or using non-steroidal, anti-inflammatory pain medications such as aspirin or similar pills while eating the food, might make a person more reactive. These additional variables are called co-factors or augmentation factors.
However, these factors are fortunately uncommon. With my patients, I encourage confidence in adding the food to the diet if it was shown to be tolerated during an oral food challenge.
Dr. Scott Sicherer is a practicing allergist, clinical researcher and professor of pediatrics. He is Director of the Jaffe Food Allergy Institute and Chief of Pediatric Allergy and Immunology at the Icahn School of Medicine at Mount Sinai in New York. He’s also the author of Food Allergies: A Complete Guide for Eating When Your Life Depends On It.
Allergists See Palforzia as Start to New Era of Food Allergy Therapies
Which Test is the Most Reliable to Know if a Child Has Really Outgrown a Food Allergy?
Sizing Up Tests to See if a Child Can Be Near a Food Allergen in a Room