Food Allergies

Food Allergies

 

Food allergies are a common form of allergic presentation in childhood.

Epidemiology

  • Incidence
    • Varies by geographic region
    • Increased incidence reported over last 10 years (especially peanut allergies)
  • Age
    • Up to 6% of children <3 years of age are affected
    • More common in children
  • Gender
    • Equal gender distribution

Risk Factors

  • History of asthma in patient
  • History of parent or sibling with atopy or asthma

Pathophysiology

  • Any food can potentially sensitize the immune system and cause production of antibody
    • However, foods that are water soluble and resistant to heat, acids and proteolysis are more likely
  • Most food allergies are IgE-mediated
    • 90% of IgE-mediated allergies are caused by only eight foods: cows milk, soy, chicken egg, peanuts, tree nuts, fish, shellfish and wheat
  • Non IgE-mediated reactions are common to soy, wheat or cows milk
  • Wheat, milk, egg and soy allergies commonly disappear with age

Clinical Presentation

  • Classic IgE-mediated (immediate hypersensitivity)
    • Reaction occurs within the hour after food ingested
    • Symptoms include urticaria, erythema, angioedema, oral pruritus, respiratory symptoms (similar to asthma or allergic rhinitis), anaphylaxis, nausea, diarrhea,
  • Mixed IgE, non-IgE
    • Occurs 1 to 24 hours after food ingested
    • Symptoms include vomiting, diarrhea, colitis, asthma, atopic dermatitis
  • Non-IgE (cell-mediated)
    • Occurs 24 hours after food ingested
    • Symptoms include diarrhea, atopic dermatitis, failure to thrive, severe or persistent infantile colic

Diagnosis

  • Laboratory Testing
    • Skin testing is no longer necessary
    • Serum IgE testing along with appropriate history
    • Food challenges may be helpful, but should not precede IgE testing

Treatment

  • Avoidance of foods that patient is sensitive to
    • Requires careful reading of packaging, in particular for nut allergies, since many products are produced in factories where nut residue may be present

Prevention

  • Avoidance of cow milk and dairy products until 6 months of age
    • Suggest breast feeding
  • Avoidance of supplemental feeding until 6 months of age
    • No solid foods until then

See Also