Food Allergy

Food Allergy is a topic covered in the Select 5-Minute Pediatrics Topics.

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Food allergy has recently been defined as “an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food.” Most commonly, the protein component of the food is responsible for the adverse immunologic response.

  • Classifications of food allergies:
    • IgE mediated, including
      • Anaphylaxis
      • Acute urticaria
      • Oral allergy syndrome
    • Non–IgE mediated (cell mediated), including
      • Food protein–induced enterocolitis syndrome (FPIES)
      • Food protein–induced allergic proctocolitis
      • Celiac disease
    • Mixed IgE and non–IgE mediated, including
      • Atopic dermatitis
      • Eosinophilic gastroenteropathies (eosinophilic esophagitis, eosinophilic gastroenteritis)
  • Most common IgE-mediated food allergies:
    • Children
      • Milk
      • Egg
      • Soy
      • Peanut
      • Wheat
      • Fish
    • Adults
      • Peanuts
      • Tree nuts
      • Fish
      • Shellfish
  • Most common non–IgE-mediated food allergies associated with food protein enterocolitis and proctocolitis:
    • Milk
    • Soy
    • Rice
    • Oat
    • Barley
    • Chicken


Food-induced anaphylaxis is the most common cause of anaphylactic reactions treated in emergency departments in the United States. The prevalence of food allergy has increased over the past 10–20 years.


  • 5% of children <5 years of age, 4% of teens and adults
  • Nearly 2.5% of infants have hypersensitivity reactions to cow’s milk during 1st year (½ of these cases are thought to actually represent GI diseases); outgrown by most (80%) by 5 years of age.
  • 1.6% have egg allergy by 2.5 years (based on population-based studies); 66% of children outgrow egg allergy by 7 years of age.
  • 0.6% of U.S. population have peanut allergy.
  • 37% of children < 5 years of age with moderate to severe atopic dermatitis have a food allergy.
  • 34–49% of children with food allergy have asthma.
  • 33–40% of children with food allergy have allergic rhinitis.
  • Fatal and near-fatal reactions are associated with uncontrolled asthma.

Risk Factors

  • Genetic
  • Family history
  • Presence of atopic dermatitis
  • Other unknown factors suspected


  • Oral tolerance to food proteins believed to develop through T-cell anergy or induction of regulatory T cells. Food hypersensitivity develops when oral tolerance fails to develop or breaks down.
  • IgE mediated: T cells induce B cells to produce IgE antibodies that initially bind on the surface of mast cells and basophils; when reexposed, the food protein binds to IgE antibodies, leading to degranulation of those cells and release of histamine and other chemical mediators.
  • Non–IgE mediated (cell mediated): T cells react to protein-inducing proinflammatory cytokines, leading to inflammatory cell infiltrates and increased vascular permeability. These factors lead to subacute and chronic responses primarily affecting the GI tract.
  • Mixed IgE and non–IgE mediated: Eosinophilic esophagitis and eosinophilic gastroenteropathy are characterized by eosinophilic infiltration of intestinal wall, occasionally reaching to serosa.

Commonly Associated Conditions

  • Asthma (4-fold more likely)
  • Allergic rhinitis (2.4-fold more likely)
  • Other atopic diseases
  • Dermatitis herpetiformis (celiac)

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