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Taking a Bite Out of
Food Allergy
Mark A. Posner, MD,
FAAAAI
Allergy and Asthma
Specialists, P.C.
Definitions
Adverse Food
Reactions
Toxic / Pharmacologic Non-Toxic / Intolerance
• Bacterial food
poisoning
• Heavy metal
poisoning
• Scombroid
fish poisoning
• Caffeine
• Alcohol
• Histamine
Non-immunologic
• Lactase
deficiency
• Galactosemia
• Pancreatic
insufficiency
• Gallbladder /
liver disease
• Hiatal hernia
• Gustatory
rhinitis
• Anorexia
nervosa
• Idiosyncratic
Adapted from Sicherer S, Sampson H. J
Allergy Clin Immunol 2006;117:S470-475.
• Eosinophilic
esophagitis
• Eosinophilic
gastritis
• Eosinophilic
gastroenteriti
s
• Atopic
dermatitis
Adverse Food
Reactions
IgE-Mediated
(most common)
Non-IgE
Mediated
Cell-
Mediated
Immunologic
• Systemic (Anaphylaxis)
• Oral Allergy Syndrome
• Immediate gastrointestinal allergy
• Asthma/rhinitis
• Urticaria
• Morbilliform rashes and flushing
• Contact urticaria
• Protein-
Induced
Enterocolitis
• Protein-
Induced
Enteropathy
• Eosinophilic
proctitis
• Dermatitis
herpetiformis
• Contact
dermatitis
Sampson H. J Allergy Clin Immunol 2004;113:805-9,
Chapman J et al. Ann Allergy Asthma & Immunol
2006;96:S51-68.
Pathophysiology
Allergens
• Proteins or glycoproteins (not fat or carbohydrate) – Generally heat resistant, acid
stable
• Major allergenic foods (>85% of food allergy)
– Children: milk, egg, soy, wheat,
peanut, tree nuts – Adults: peanut, tree nuts,
shellfish, fish, fruits and vegetables
CASE: Crustacean Allergy:
IgE Towards Protein in the
Food, NOT Iodine
• 79 year old man had anaphylaxis to
shrimp at age 20, 25
• Doctors told him he was allergic to iodine in seafood
• Avoided seafood, iodized salt for years
• Age 70: retirement dinner, hostess picked shrimp out of his portion and gave it to him --- ER visit for anaphylaxis
• At age 79, specific IgE measurement extremely high to shrimp: >100 kU/L
• On follow-up after education on avoidance, happily consuming foods with iodized salt because he didn’t have to screen salt source any more
Pan-allergens
• Proteins in food, pollen or plants that possess homologous IgE binding epitopes across species
• 1/3 of children with moderate to severe atopic dermatitis may have food allergy (especially cow’s milk, egg, soy, wheat). Morbilliform rashes may be seen in these children upon food challenge.
• Contact dermatitis (food handlers)
Respiratory Responses
• Upper and lower respiratory
tract symptoms may be seen
(rhinoconjunctivitis, laryngeal
edema, asthma)
• Rarely isolated, usually
accompany skin and GI
symptoms
• Inhalational exposure may
cause respiratory symptoms
that can be severe • Occupational
• Restaurants
• Kitchen/Home Examp
le:
crabs
to be
boiled
Birch Apple, carrot, celery,
cherry, pear, hazelnut
Ragweed Banana, cucumber,
melons
Grass Melon, tomato, orange
Mugwort Melon, apple, peach,
cherry
Pollen-Food
Syndrome or Oral
Allergy Syndrome
• Clinical features: rapid onset oral
pruritus, rarely progressive
• Epidemiology: prior sensitization to
pollens
• Key foods: raw fruits and vegetables
• Allergens: Profilins and pathogenesis–
related proteins
– Heat labile (cooked food usually
OK)
• Cause: cross reactive proteins
pollen/food
Latex-Fruit
Syndrome
• 30-50% of those with latex allergy are sensitive to some fruits due to cross-reactive IgE
• Most common fruits: banana, avocado, kiwi, chestnut but other fruits and nuts have been reported
• Can clinically present as anaphylaxis to fruit
• Warn latex-sensitive patients of potential cross-reactivity
• Some fruit-allergic patients may be at risk for latex allergy
Enterocolitis Enteropathy Proctitis Age Onset: Infant Infant/Toddler Newborn Duration: 12-24 mo ? 12-24 mo 9 mo-12 mo Characteristics: Failure to thrive Malabsorption Bloody stools Shock Villous atrophy No systemic sx Lethargy Diarrhea Eosinophilic Vomit Diarrhea
Non-IgE-mediated, typically milk and soy
induced
Spectrum may include colic, constipation
and occult GI blood loss
Pediatric
Gastrointestinal
Syndromes
Fully reviewed in: Sicherer SH. Pediatrics
2003;111:1609-1616.
GI Syndromes of Children
and Adults:
Celiac Disease (Gluten-sensitive enteropathy) – In children:
• FTT, or weight loss
• Malabsorption, diarrhea, abdominal pain
• May be subtle
– In adults, average 10 years of nonspecific symptoms:
• Diarrhea, abdominal pain
• GERD
• Malabsorption
• May present atypically with osteoporosis, infertility, neurologic sx
Pathophysiology: an immune-mediated enteropathy triggered by gluten peptides in genetically predisposed patients (DQ2 or DQ8)
– Lymphocytic infiltration of small bowel
– Villus atrophy
Celiac Disease
(Gluten-sensitive
enteropathy) Cont’d: • Diagnosis
– ~1/133 people in US have celiac disease – many are currently undiagnosed
– IgA anti-tissue transglutaminase (IgG if IgA-deficient), anti-endomysial Ab, little role for anti-gliadin Ab currently due to poor specificity
– Upper endoscopy with biopsy; refer to gastroenterologist
• Management – Strict, lifelong, gluten avoidance
(wheat, barley, rye)
– Rare risk of GI lymphoma
– Oats almost always OK
– Link with resources: dietician, local support groups, national organizations (listed at www.celiac.nih.gov)
AS of January 1, 2006, all food containing “Big Eight Allergens” (cow’s milk, peanut, tree nut, hen’s egg, soy, wheat, fish, crustacean) in the U.S. MUST declare the ingredient on the label in COMMON language. Does NOT apply to non-Big 8 allergens (e.g., sesame).
Label reading used to be very
challenging!
Example: Cow’s Milk
Food Allergen Labeling and Consumer
Protection Act of 2004 (P.L. 108-282)
(FALCPA)
Management: Infant
Formulas
• Soy (confirm soy IgE negative)
– <15% soy allergy among IgE-CMA
– ~50% soy allergy among non-IgE CMA
• Cow’s milk protein extensive hydrolysates
– >90% tolerance in IgE-CMA
• Partial hydrolysates
– Not hypoallergenic!
• Elemental amino acid-based formulas
– Lack allergenicity
* CMA=cow’s milk allergy
Management:
Emergency Treatment of
Anaphylaxis • Epinephrine: drug of choice
– Self-administered epinephrine readily available at all times
American Academy of Pediatrics Committee on Nutrition.
Pediatrics 2000;106:346-9.
Food Allergy Prevention
• Exclusive breastfeeding for at least 4 months decreases eczema and cow milk allergy in the first 2 years of life in infants at high risk for atopy
• Recent studies (Fox) show early oral intake of peanuts decreases peanut allergy while env. exposure alone increases the risk
• Du Toit showed that peanut allergy was 10-fold higher in Jewish children in the UK vs. Israel where peanut is introduced early
Fox AT, et al. J Allergy Clin Immunol 2009;123:417-23.
Du Toit G, et al. J Allergy Clin Immunol 2009;122:984-91.
Ongoing Studies
• The Food Allergy Research
Consortium-NIH sponsored
consortium to study food
allergy
• Now underway:
Observational study of solids in
infants>4mo
Egg oral immunotherapy
Peanut sublingual
immunotherapy
Recombinant peanut vaccine
safety study
Future Approaches
Future Immunomodulatory
Approaches
• Recombinant anti-IgE antibody
• Gene (naked DNA) immunization
• Mutated B-cell epitopes
• Minimal T-cell epitopes
• Immune-modulating adjuvants (ISS)
• Probiotics
• T lymphocyte manipulation to induce
tolerance
• Chinese herbal remedies (Food
Allergy Herbal Formula)
TH0 TH1
TH2
TH2
TH1
Tolerance (immune deviation)
Sensitization
“atopics”
“Non-
atopics”
antigen
IgE
cDNA, Probiotics Peptides/Epitopes
Immune
Modulation
Anti-IgE Sicherer SH, unpublished
Role of the Allergist
Reasons for Allergy
Referral
• Persons who have limited their diet based upon perceived adverse reactions to foods or additives.
• Persons with a diagnosed food allergy
• Atopic families with, or expecting, a newborn who are interested in identifying risks for, and preventing, allergy.
• Persons who have experienced allergic symptoms in association with food exposure.
• Persons who experience an itchy mouth from raw fruits and vegetables.
Leung D, et al. J Allergy Clin Immunol
2006;117:S495-523.
Reasons for Allergy
Referral (Cont’d)
• Infants with recalcitrant gastroesophageal reflux or older individuals with recalcitrant reflux symptoms, particularly if they experience dysphagia.
• Infants with gastrointestinal symptoms including vomiting, diarrhea (particularly with blood), poor growth, and/or malabsorption whose symptoms are otherwise unexplained, not responsive to medical management, and/or possibly food-responsive (even if screening allergy tests are negative).
• Persons with known eosinophilic inflammation of the gut.