Study: We Need Evidence-Based Guidelines for Food Allergies
The term “Evidence-Based Treatment” or “Evidence-Based Medicine” refers to an approach for health interventions based on scientific research and guidelines that are consistent, regardless of where you seek treatment. Food allergy diagnoses are no different, and a recent review of past studies finds that there is a lack of an accepted definition or evidence-based guidelines for determining true allergic reactions to food. Researchers say that this is hindering efforts to determine their prevalence among both children and adults, and in evaluating new treatment options.
“Right now there are just too many different definitions of what food allergies are,” study researcher Jennifer J. Schneider Chafen, MD, of the VA Palo Alto Healthcare System tells WebMD. “A true food allergy can be life threatening, but many people who just can’t tolerate a particular food are told they have food allergies.”
The most common foods that cause allergic reactions are milk, eggs, peanuts, tree nuts, fish, shellfish, soy and wheat. These eight foods account for about 90% of all food-related allergic reactions, according to information from the Food Allergy and Anaphylaxis Network.
The study, funded by the National Institute of Allergy and Infectious Diseases (NIAID), reviewed 72 past studies on food allergies that were published between January 1988 and September 2009.
According to author Dr. Marc Riedl, allergist and immunologist at the University of California, although about 30% of the population believes that they have a food allergy, true incidence is only about 8% for children and less than 5% for adults.
Part of the confusion is the difference between a food allergy and a food intolerance. Headaches from sulfites in wine or gastric distress from lactose in milk are examples of intolerances and not true allergies.
According to the research, a food challenge in the presence of a qualified healthcare professional, either in a doctor’s office or a hospital setting, is the most reliable way to confirm a specific food allergy, but this can be costly, time-consuming, and dangerous, as it can result in anaphylaxis.
Most physicians use either a “skin prick” test or a blood test, which is less reliable and often leads to overdiagnosis. The skin test, which looks for IgE antibodies that are associated with allergies, is only about 50% accurate, according to Dr. Schneider-Chafen, because these antibodies can be transient and not necessarily diagnostic of a true allergy.
Lynda Mitchell, president of “Kids with Food Allergies, says ““We tell parents that about half the time a skin prick or blood test may not be accurate and that patient history, physical examination, and other factors need to be considered.”
The NIAID is currently working on guidelines for the diagnosis and management of food allergies which should be released in the late summer or fall. “Having a basic framework for diagnosing food allergies will help us better interpret studies evaluating diagnosis and treatment,” says Schneider-Chafen.
Schneider Chafen JJ, et al "Diagnosis and managing common food allergies" JAMA 2010; 303(18): 1848-56.