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Tuesday, September 2, 2014
A food allergy is an adverse reaction to food that involves a response by the body's immune system. Most commonly, the body reacts to the food protein by producing immunoglobulin E (IgE) antibodies which, in turn, cause the release of histamine and other chemicals that produce allergy symptoms. Allergic reactions may occur immediately or may be delayed for up to 24 hours, making it difficult to identify the food culprit. Symptoms range from nausea and vomiting to skin rashes, hives, asthma, and anaphylaxis, a life-threatening reaction that may cause difficulty breathing, decreased blood pressure and loss of consciousness.
A food allergy is different than a food intolerance, which is also an adverse reaction to food. A food intolerance does not cause an immune response. It may be caused by the lack of an enzyme that is needed for the digestion or absorption of specific food components. Lactose intolerance is an example of a common food intolerance that causes gastrointestinal symptoms, such as cramping and bloating, when dairy foods are eaten.
Food allergies can be diagnosed in three ways:
(1) A prick skin test using tiny amounts of the suspected allergen
(2) A blood test to determine IgE antibodies
(3) An elimination diet in which the suspected allergen is not eaten for two to four weeks.
A food allergy is treated by avoiding the problem food. Therefore, persons with allergies must read all food labels since some products contain unexpected allergens. Drugs such as antihistamines and epinephrine can be prescribed to treat the symptoms of allergies.
The following eight foods cause 90% of all allergic reactions:
In children, allergic reactions are usually caused by milk, eggs and peanuts.
The Food Allergen Labeling and Consumer Protection Act of 2006 requires food products that contain the eight most common allergens to list that information on the ingredient list. If the product contains nuts or seafood, the label must list the specific type.
Scientists believe that food allergies are on the rise and currently occur in about 12 million Americans. Hopefully, future research will provide valuable information about the causes, diagnosis and treatment of food allergies. For more information, you can visit the Food Allergy & Anaphylaxis Network.
This article originally appeared in Nutri-bytes (March 2009), a service of the University of Cincinnati College of Nursing and was adapted for use on NetWellness with permission.
Last Reviewed: Feb 24, 2011
Bonnie J Brehm, PhD, RD
Professor of Nursing
College of Nursing
University of Cincinnati