Food Allergy Triggers & Where They Hide Slideshow Pictures Take the Quiz on Allergies 10 Common Allergy Triggers Slideshow Pictures

Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Food Allergy Myths

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Jay W. Marks, MD

Food allergies are often misunderstood, even though societal recognition of, and education about, the condition is increasing. See if you have heard ? or believed ? any of the following myths about food allergies:

1. "You're "allergic" to any food that gives you problems." This statement is false, since there are several problems that can arise after eating specific foods, the majority of which are unrelated to allergy. True allergies to foods are immunologic reactions involving the class of immunoglobulins (proteinsthat assist in the body's immune response) known as immunoglobulin(Ig) E. Other kinds of reactions to foods that are not food allergies include food intolerances (such as lactose or milk intolerance), food poisoning, and toxic reactions. The prevalence of food allergy in the population is much lower than the prevalence of adverse reactions to foods. It is estimated that true food allergies occur in 2-5% of the population.

Find out about peanut and fruit allergies »

Food allergy facts

• Food allergy is not common but can be serious.



• Food allergy differs from food intolerance, which is far more common.



• The more frequent types of food allergies in adults differ from those in children.



• Children can outgrow their food allergies, but adults usually do not.



• The diagnosis of food allergy is made with a detailed history, the patient's diet diary, or an elimination diet.



• Food allergy is treated primarily by dietary avoidance.

Introduction to food allergies

Either food allergy or food intolerance affects nearly everyone at some point. When people have an unpleasant reaction to something they ate, they often think that they have an allergy to the food. Actually, however, only about 3% of adults and 6%-8% of children have clinically proven true allergic reactions to food.

This difference between the prevalence of clinically proven food allergy and the public's perception of the problem is due primarily to misinterpreting food intolerance or other adverse reactions to food as food allergy. A true food allergy is an abnormal response to food that is triggered by a specific reaction in the immune system and expressed by certain, often characteristic, symptoms. Other kinds of reactions to foods that are not food allergies include food intolerances (such as lactose or milk intolerance), food poisoning, and toxic reactions. Food intolerance also is an abnormal response to food, and its symptoms can resemble those of food allergy. Food intolerance, however, is far more prevalent, occurs in a variety of diseases, and is triggered by several different mechanisms that are distinct from the immunological reaction responsible for food allergy.

People who have food allergies must identify and prevent them because, although usually mild and not severe, these reactions can cause devastating illness and, in rare instances, can be fatal.

How do allergic reactions to food occur?

The allergens in food are those components that are responsible for inciting an allergic reaction. They are proteins that usually resist the heat of cooking, the acid in the stomach, and the intestinal digestive enzymes. As a result, the allergens survive to cross the gastrointestinal lining, enter the bloodstream, and go to target organs, causing allergic reactions throughout the body. The mechanism of food allergy involves the immune system and heredity.

Immune system: An allergic reaction to food involves two components of the immune system. One component is a type of protein, an allergy antibody called immunoglobulin E (IgE), which circulates through the blood. The other is the mast cell, a specialized cell that stores up histamine and is found in all tissues of the body. The mast cell is particularly found in areas of the body that are typically involved in allergic reactions, including the nose and throat, lungs, skin, and gastrointestinal tract.

Heredity: The tendency of an individual to produce IgE against something seemingly as innocuous as food appears to be inherited. Generally, people with allergies come from families in which allergies are common -- not necessarily to food but perhaps allergies to pollen, fur, feathers, or drugs. Thus, a person with two allergic parents is more likely to develop food allergies than someone with one allergic parent.

Mechanism: Food allergy is a hypersensitivity reaction, meaning that before an allergic reaction to an allergen in food can occur, a person needs to have been exposed previously, or "sensitized," to the food. At the initial exposure, the allergen stimulates lymphocytes (specialized white blood cells) to produce the IgE antibody that is specific for the allergen. This IgE then is released and attaches to the surface of the mast cells in different tissues of the body. The next time the person eats that particular food, its allergen hones in on the specific IgE antibody on the surface of the mast cells and prompts the cells to release chemicals such as histamine. Depending upon the tissue in which they are released, these chemicals cause the various symptoms of food allergy.