If a food allergy is suspected and tests are inconclusive, a food challenge helps an allergist to determine whether the patient has an allergy. In a food challenge, the doctor observes a patient’s reaction to the suspected food allergen, Hartz says. The food challenge is conducted in a lab or a doctor’s office with epinephrine and resuscitation on hand if a patient should start to have a serious reaction.
GETTING SCHOOLED. New federal guidelines promote training and the availability of epinephrine injectors in schools.
You should know that testing methods exist that NIAID says shouldn’t be relied on to diagnose a food allergy. In 2010, NIAID released guidelines on food-allergy diagnosis and management that list tests that it considers to be “unproven” or “nonstandardized.” These include tests of muscle, cytotoxicity (cells), hair, pulse and electrical properties of skin. These tests typically are promoted by practitioners of alternative medicine; some are available as at-home kits.
NIAID says no evidence demonstrates that any of these nonstandardized tests has any value in diagnosing food allergies. Consequently, the institute’s guidelines say, these test results might cause “false positive or false negative diagnoses, leading to unnecessary dietary restrictions or delaying the appropriate diagnostic workup, respectively.” In other words, FARE says, results from an unproven test might mislead you to believe that you aren’t allergic to a certain food and lead to a potentially dangerous situation if you consume it.
NIAID says its diagnosis guidelines are designed not only for allergists/immunologists but also for doctors of family medicine, internal medicine, pediatrics and other specialties. FARE and American Academy of Allergy, Asthma & Immunology (AAAAI) and American College of Allergy, Asthma & Immunology (ACAAI) recommend that an allergist/immunologist tests you for the best results. These doctors have advanced schooling and clinical experience. The organizations say this equates to a more accurate diagnosis. Doctors whom we contacted say you don’t have to be an allergist to test for food allergies, although allergists might have more specific familiarity of treatments.
Another obstacle in food-allergy diagnosis is that the line between food allergies and food intolerance is blurred, because symptoms overlap. No clear statistic exists on how many people have food intolerance: Our research turned up estimates of 2 percent to 25 percent.
According to Mayo Clinic, the difference between a food allergy and food intolerance is that food intolerance often is caused by the absence of an enzyme that’s required to digest the offending food fully, experts say. An individual’s reaction to a food’s naturally occurring or added chemicals also can cause food intolerance. One way that you can tell the difference is that an allergic reaction typically comes on quickly, within an hour, experts say, while a reaction from food intolerance is more gradual—taking hours or even days to appear. Further, those who have a food allergy react negatively to a small amount of food, while those who have food intolerance might be able to eat a small amount of food and have no reaction, according to Cleveland Clinic.
Although a food allergy is triggered each time that food is consumed, food intolerance typically is dose-related. For example, Cleveland Clinic says a person who has a lactose intolerance might be able to drink milk that’s in coffee or even a single glass of milk, but he/she will become sick if he/she drinks several glasses of milk.
NO CURE. Food allergies have no cure, Nowak-Wegrzyn says. People who have a food allergy must manage the condition through dietary control and by limiting exposure to the allergen. However, research is underway on potential ways to reduce, if not eliminate, allergic reactions to food. For instance, Nowak-Wegrzyn found in studies that she conducted in 2008 and 2011 that about 70 percent of children who are allergic to milk can tolerate it in baked goods, because the high temperature of baking destroys the protein to which their bodies react. Still, NIAID recommends that children who are allergic to milk should see their doctor before they try a baked food that’s made with milk.
Other areas of study include sublingual immunotherapy, in which a food allergen is held under the tongue, and oral immunotherapy, in which the allergen is given in small amounts and the amount increases over time. The aim of both of these strategies is to desensitize an allergic person to the food and build a tolerance over time. Research centers report positive results through desensitization. For example, scientists in Britain reported in the January 2014 issue of The Lancet that after 6 months of oral immunotherapy, at least 84 percent of children who had a severe peanut allergy could eat about five peanuts per day safely.