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Food Allergy (cont.)

Food Allergy Causes

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, most 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.
Medically Reviewed by a Doctor on 5/20/2016
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