Food Allergy

Aka: Food Allergy

1. See Also
   1. Anaphylaxis
   2. Pollen-Food Allergy Syndrome
   3. Cow's Milk Allergy
2. Epidemiology
   1. Incidence of Food Allergy
      1. Adults: 2-3%
      2. Children: 4-5% (many more believe they have a Food Allergy, but are unproven)
3. Risk Factors
   1. Family History of atopic disease (Atopic Dermatitis, Asthma, Allergic Rhinitis)
4. Causes: Common Food Allergies
   1. Children
      1. Cow's Milk Allergy
      2. Egg Whites
      3. Wheat
      4. Soy
      5. Peanuts
   2. Adults
      1. Crustaceans (e.g. shrimp, lobster)
      2. Tree nuts
      3. Peanuts
      4. Fish
5. Causes: Food Allergies associated with Anaphylaxis
   1. Nuts (allergy often seen in Atopic Patients)
      1. Peanuts (legume)
      2. Tree nuts
         1. Pistachios
         2. Walnuts
         3. Cashews
         4. Almonds (and marzipan)
         5. Hazelnuts or filberts
         6. Macadamian Nuts
         7. Pecans
         8. Brazil nuts
         9. Pine nuts
   2. Fish
   3. Shellfish
      1. Crab
      2. Crayfish
      3. Prawns or shrimp
      4. Lobster
   4. Seeds
      1. Sesame seeds
      2. Sunflower seeds
      3. Caraway seeds
6. Causes: Cross-reactivity with contact or air-borne allergans
   1. See Oral Allergy Syndrome
   2. Latex Allergy
      1. Banana
      2. Kiwi
      3. Avocado
   3. Birch pollen allergy
      1. Carrot
      2. Celery
      3. Hazelnuts
      4. Parsnips
      5. Potatoes
      6. Fresh fruit (apples, cherries, peaches, pears...)
   4. Grass pollen
      1. Kiwi
      2. Tomato
   5. Ragweed pollen
      1. Bananas
      2. Melons
7. Pathophysiology
   1. Initial reaction (Sensitization)
      1. IgE antibodies produced to food
   2. Subsequent Reaction
      1. IgE fixed to Mast Cells in Skin, GI, Respiratory
      2. Reacts to allergen
      3. Releases
         1. Histamine
         2. Chemotactics attract Eosinophils
         3. Prostaglandins and leukotrienes are released
8. Symptoms
   1. Skin
      1. Urticaria (Hives)
      2. Atopic Dermatitis
   2. Respiratory
      1. Allergic Rhinitis
      2. Asthma
   3. Gastrointestinal
      1. Vomiting
      2. Blood in stool
      3. Diarrhea
   4. Anaphylaxis
9. Differential Diagnosis: Postprandial collapse
   1. Airway Foreign Body
   2. Non-allergic food reaction
      1. Monosodium glutamate
      2. Sulfite reaction
      3. Scombroid Fish Poisoning (vasoactive amines)
10. Differential Diagnosis: Non-allergic gastrointestinal food reactions
    1. Lactose Intolerance
    2. Irritable Bowel Syndrome
    3. Carcinoid Syndrome
    4. Giardiasis
    5. Celiac Sprue
11. Diagnosis
    1. Immediate Reacting IgE skin Test
       1. Epicutaneous stick with Fresh Food Extract
       2. Sensitive and Specific
       3. Do NOT perform for food suspected of Anaphylaxis
    2. In-Vitro test for allergen-specific IgE Antibodies (RAST)
       1. Less sensitive than skin test
       2. Safe alternative to skin test (Anaphylaxis suspected)
    3. Open Food Challenge
       1. Use for reintroduction of foods after 2-3 years
          1. For foods with less serious reactions
             1. Example: Hives to milk or eggs
       2. Diet diaries
       3. Short-term Elimination Diets
12. Management: Milk Allergy or intolerance with GI Symptoms
    1. Differentiate from Infantile Colic
       1. Colic will resolve spontaneously after 3-4 months
       2. Milk substitution is unnecessary
    2. Substitute Casein Hydrolysate (Cow's Milk) Formula
       1. Nutramigen, Pregestimil, Alimentum
       2. Soy-based formula is not appropriate substitution
13. Management: Anaphylaxis reaction history
    1. Indefinitely avoid causative food
    2. Epinephrine Self-Injectors for home/school (Should have 2 pens available)
       1. Child over age 6
          1. Epinephrine (1:1000) 0.3 mg SQ (EpiPen)
       2. Child under age 6
          1. Epinephrine (1:2000) 0.15 mg SQ (Epi-Pen Jr)
14. Management: Reintroduction of prior food allergies
    1. Mix with other foods
       1. Eggs in baked products (instead of scrambled eggs)
       2. Milk in Cheese or yogurt (instead of glass of milk)
    2. Do not reintroduce foods with previous Anaphylaxis
15. Management: Specific food Issues
    1. Egg Allergy and MMR and flu Vaccination
       1. MMR and flu vaccines contain minute egg amounts
       2. If tolerates egg containing foods
          1. MMR and Influenza Vaccine ok
       3. If unsure:
          1. Skin test
          2. Monitor for 2 hours after vaccination
    2. Fish Allergy
       1. Avoid fresh and saltwater fish
       2. Most fish-allergic patients can tolerate canned tuna
    3. Nut allergy (often associated with Anaphylaxis)
       1. Do not eat at buffets
       2. Avoid unlabeled candies and desserts
       3. Avoid ice cream parlors
    4. Milk allergy
       1. Avoid not only cow's milk, but also sheep and goat's milk
       2. Avoid butter or margarine containing milk
    5. Crustacean allergy
       1. Avoid all crustaceans (shrimp, lobster, crab...)
16. Associated Conditions
    1. Oral Allergy Syndrome
    2. Food dependent Exercise induced Anaphylaxis (rare)
       1. Wheat is most common associated food trigger
       2. Anaphylaxis occurs only if specific food trigger ingested before Exercise
       3. Space Exercise at least 6 hours after trigger food is ingested
    3. Food-induced Urticaria
       1. Food allergies account for 30% of acute cases but rarely cause chronic Urticaria
    4. Atopic Dermatitis
       1. Improves when eggs, milk and peanuts are removed from diet
17. Associated Conditions: Conditions NOT associated with Food Allergy
    1. Abnormal Child Behavior
       1. Myths:
          1. Hyperactivity, Insomnia, Anxiety (Shannon,1922)
          2. "Allergic Attention Fatigue Syndrome" (Rowe, 1950)
       2. Reality
          1. No proven relationships
    2. Attention-Deficit Disorder (ADD)
       1. Myth: Attention Deficit Disorder related to dietary additives
          1. Dietary Salicylates
          2. Artificial food colors and flavors
             1. Feingold, 1975
       2. Reality
          1. Only 2% ADD Children would benefit from diet change
       3. Reference
          1. Lipton (1983) J Am Diet Assoc 83:132-4
    3. Sugar "Allergy"
       1. Myth: Refined sugars aggravate behavioral problems
          1. Suggested to provoke hyperactivity, aggressive, inappropriate behavior
       2. Reality
          1. Sugar does not increase activity
             1. Milich (1986) Clin Psychol Rev 6:493-513
             2. Mahan (1988) Ann Allergy 61:453-8
          2. Sucrose has "calming effect" when c/w Aspartame
             1. Kruesi (1986) Annu Rev Nutr 6:113-30
             2. Bachorowski (1990) Pediatrics 86:244-53
18. Prognosis
    1. Transient Food Allergies
       1. Most food allergies last only a few years
       2. Milk, eggs, wheat or soy allergies usually resolve
          1. Egg allergy: 70% resolve by age 5 years
          2. Milk allergy: 85% resolve by age 5 years
    2. Lifelong Food allergies
       1. Foods associated with systemic Anaphylaxis
       2. Nuts, fish, seeds allergies persist
19. Resources
    1. Food Allergy and Anaphylaxis Network
       1. http://www.foodallergy.org
20. References
    1. Anderson (1997) Am Fam Physician 56(5): 1365-74
    2. Kurowski (2008) Am Fam Physician 77(12):1678-86
    3. Moneret-Bautrin (2005) Curr Allergy Asthma Rep 5(1):80-5
    4. Nowak-Wegrzyn (2006) Med Clin North Am 90(1):97-127
    5. Sampson (2002) N Engl J Med 346:1294-9