Food allergy: separating fact from fiction
By Richard L. Wasserman, MD, PhD, FAAAAI
People are often confused about food allergy and whether it is the cause of their or their child’s problem. Some key information will help you separate fact from fiction.
These tips will give you a working understanding of food allergy and help you decide if you should consult an allergist/immunologist.
Food allergy is a myth. Fiction. Food allergy is a well-understood medical problem that causes a clearly defined set of symptoms. Allergist/immunologists do make a distinction between food allergy and food sensitivity. People who get headaches from wine, gas from beans, diarrhea from lactose or a runny nose from spicy food have food sensitivity. People who develop hives, itchy mouth, throat closing, cough, wheezing or shock from peanuts, shellfish or milk have food allergy.
Food allergy is hard to diagnose because you never know when you are going to react to the food. Fiction. If a person is allergic to a food, they will have an allergic reaction to that food every time they eat it. People with food allergy usually have a reaction soon after eating the food, generally within 15 to 60 minutes. Most people who have a true food allergy know what food they are allergic to before they speak with an allergist/immunologist. For some people, each reaction is the same. For example, each time they eat shellfish, they get hives. For many people, however, each reaction is worse than the last. A food exposure that caused wheezing the last time may cause respiratory distress or shock the next time.
People with food allergy are allergic to so many foods that they couldn’t eat if they avoided all of them. Fiction. Studies have shown that the vast majority of people with food allergy are actually allergic to only one or two foods. People with a food allergy often think they are allergic to many different foods because they are not aware that their problem food is a hidden ingredient in a variety of foods. For example, a person who is allergic to milk may not know that some brands of water-packed tuna have non-fat dry milk added to them, or that some hot dogs have milk protein as an ingredient.
Food allergy is diagnosed by food allergy testing. Fiction and fact. Most of the time, food allergy is diagnosed by history. Food allergy skin testing or food allergy blood tests (RASTs or CAPRASTs) are often helpful, but do not, by themselves, make a diagnosis. Food allergy testing may give a false positive. This is particularly true if the tested food has not caused an identifiable reaction. The only sure way to diagnose food allergy is with a food challenge. In a food challenge, the patient is given the food suspected of causing the reaction to bring on some symptoms of food allergy. This procedure is safe if performed by an experienced physician in a controlled environment. Food challenges give the most reliable information about whether a person is allergic to a food.
Food allergy can be treated by “desensitization” with shots or drops. Fiction. At this time, the only treatment for food allergy is to completely avoid the problem food. Researchers are looking for treatments for food allergy, but no approach has been shown to be safe and effective in humans.
©2006, American Academy of Allergy, Asthma and Immunology. All rights reserved. This article has been reproduced with permission of AAAAI as a member of their assocatiion.