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Medical Author:

Jatinder Singh, MD

Coauthor:

Mark Clark, MD

Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

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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An allergic reaction occurs when the body's immune system overreacts to an allergen, in this case a food protein.

• The white blood cells produce an antibody to this allergen, called immunoglobulin E or IgE.
• When this antibody comes in contact with the particular food protein, it promotes production and release of certain chemicals called "mediators." Histamine is an example of a mediator.
• These mediators act on various parts of the body, mainly the skin, throat, airways, intestines, and heart.
• The effects of the mediators on organs and other cells cause the symptoms of the allergic reaction.
• Any food has the potential to trigger an allergic reaction, but a few foods account for most food allergies. In fact, about 90% of food allergies are triggered by one of these eight foods:
• Eggs
• Milk
• Wheat
• Soy
• Peanuts
• Tree nuts
• Fish
• Shellfish
• Generally, people who have allergies react to only a few foods. Occasionally, a person who is allergic to one food also may be allergic to other related foods. This is called cross-reaction. Common examples:
• Allergy to peanuts -- Cross-allergies to soybeans, green beans, and peas
• Allergy to wheat -- Cross-allergy to rye
• Allergy to cow's milk -- Cross-allergy to goat's milk
• Allergy to pollen -- Cross-allergies to foods such as hazelnuts, green apples, peaches, and almonds
• People who have a history of other allergies, such as eczema or asthma, are particularly prone to having a reaction to a food. They are also more likely to have a more severe reaction.

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