Defining Food Allergies

Posted by The Editorial Desk / Tuesday, May 18th, 2010

Last week, May 9-15, was Food Allergy Awareness Week.  Established in 1997 by the Food Allergy and Anaphylaxis Network (FAAN), the week serves to increase awareness about the growing food allergy problem. 

Over 12 million American have food allergies and one in every 17 children under the age of 3 has food allergies.  According to the CDC, the number of people diagnosed with food allergies increased by 18 percent over the last decade. 

However, the New York Times highlights a recently published National Institute of Allergy and Infectious Diseases study, Diagnosing and Managing Common Food Allergies, which states the prevalence of food allergies is limited by a lack in consistent diagnostic methods, including the actual definition of a food allergen.  Some people often confuse food intolerance for a food allergy.  The release of the report coincided with Food Allergy Awareness Week.

Current testing includes testing for the antibody Immunoglobulin E (IgE).  But, according to the NY Times article and an ABC News report, just because IgE is present, it does not necessarily mean one is allergic to a certain food.  According to Dr. Hugh Sampson, chief of pediatric allergy and immunology at New York’s Mount Sinai School of Medicine, “a positive skin test only translates into a true allergy 35 to 40 percent of the time.”

(Video: ABC News)

So what’s the best way to determine if you are allergic to certain foods?  The following excerpt from the ABC News report provides some helpful information:

The two main allergy tests, the skin test, and a blood serum test — which looks for antibodies in the blood for specific foods — are not conclusive on their own, Sampson says.

“The tests are good for telling us if someone has antibodies for a food, not so good for telling us if someone will have a reaction to the food,” he says. “The more antibodies you have, the higher the likelihood of an allergic reaction, but even that’s not full proof,” he adds.

So if you’ve been diagnosed as allergic after one of those tests, but you haven’t had an allergic reaction to that food in the past, it’s likely that you are not actually allergic, Sampson says.

The “gold standard” of allergy testing is something called an oral food challenge, Riedl says, in which small amounts of the food in question are disguised and given to the patient while they are under observation. This is best done if the patient doesn’t know if they are actually getting the food so they don’t anticipate a reaction.

Unfortunately, this type of test is time-consuming, so many doctors are reluctant to do it, Riedl says.

The results of the study will help experts re-write guidelines on defining, diagnosing, and treating food allergies by the end of June. 

–Aisha Salazar

Tags: Aisha Salazar, definition, diagnosis, food, food allergy, Gut Check, misdiagnosis, National Institute of Allergy and Infectious Diseases, Northern Virginia Magazine