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Food Allergies
What are they and can we prevent them?
Heather Mileski, RD Pediatric Gastroenterology and Nutrition, MCH
Outline
Define allergy Differentiate between types of allergies Discuss diagnostic tools available Treatment Consider preventative measures
What is the incidence of food allergy in young children?
a) <10%
b) 10-20%
c) 20-30%
d) >30%
Garcia-Careaga, 2005
Definitions
Allergy – “a pathological immune reaction to a food protein”
Adverse food reaction – “an ill effect as a result of the intake of food”
• Intolerances, sensitivities, enzyme deficiency (e.g. galactosemia, disaccharidase, etc), pharmacological effect (e.g. food dyes, preservatives, MSG, caffeine, etc)
Type 1: IgE-mediated (immune)
Immediate Hypersensitivity Disorder– Symptoms occur in minutes to hours– Can become anaphylactic– Common triggers are milk, soy, egg,
peanut, shellfish, wheat– 80% resolve after several years with the
exception of peanut and shellfish
Garcia-Careaga et al, 2005
Type 1: IgE-mediated
Oral Allergy Syndrome/Pollen-Food Allergy Syndrome– Symptoms occur in minutes to hours– Reaction limited to oral cavity – Rarely systemic symptoms– Common triggers are RAW fruit and
vegetables– Cross-reaction with airborne allergens
Oral Allergy Syndrome
Airborne Allergen Food Allergen
Birch Apples, pears, celery, hazelnuts, kiwi, potatoes, carrots
Ragweed Melons (includes cucumbers) and bananas
Grass pollen Tomatoes
Type III and IV:Non-Immune Mediated Proctocolitis (Cow’s Milk Protein Colitis)
– Occurs in infancy resolves between 6 months-2 years
Dietary Food Enteropathy – Occurs in infancy, usually resolves in first 2
years of life
Mixed IgE and Non-IgE
Eosinophilic Gastroenteritis– Eosinophilic infiltration of esophagus,
stomach and small bowel mucosa Eosinophilic Esophagitis Both conditions diagnosed by biopsy
Other Adverse Food Reactions
Lactose Intolerance– Reaction to milk sugar NOT protein
Dietary Fructose Intolerance– Reaction to the sugar fructose
Food Sensitivities e.g. gluten
Conventional Diagnostic Tools
IgE-Mediated Skin prick testing RAST– blood test Double-blind
placebo control challenge
Non-IgE Stool samples for
blood, pus cells Endoscopy with
biopsy Elimination diets
Alternative Diagnostic Tools
Name of Test Testing Technique
IgG ELISA (variety of specific tests e.g. IgG4)
Serum sample
sIgA ELISA Saliva sample
Kinesiology Muscle strength testing
Vega Testing Measures electro-magnetic pulses through the body
Carroll Testing Measures enzyme defects or deficiencies via a blood sample placed in electric current
Herman and Drost, 2004
Treatment Avoidance
– IgE-mediated allergies require strict avoidance of the allergen
– Adverse food rxns are dose-dependent Education
– Children and parents need detailed education on label reading
Which of the following is NOT a milk protein?
a) Casein
b) Lecithin
c) Whey
Is Prevention Possible?
No evidence for prevention in general population
Some evidence in high risk infants – High risk = first degree relative with atopy
(eczema, food allergy, asthma, allergic rhinitis)
Prevention Guidelines – AAPOnly for High Risk Infants
2000 Pregnancy possibly restrict peanut Exclusive breastfeeding for 6 months Eliminate peanuts & nuts from lactation diet
(consider eggs, cow’s milk, fish) If bottle-fed use hypoallergenic formula
(extensive of partial hydrolysate) Solids at 6 mo; cow’s milk at 12 mo; eggs at
24 mo; peanuts, nuts and fish at 36 mo
Prevention Guidelines 2004 Euro Academy of Allerg and Clin Immunol
Breastfeed exclusively for 4 months If bottle-fed use extensively hydrolyzed
formula Solids at 4 to 6 months Additional studies required to
demonstrate any preventive effects of further dietary restriction
Prevention Guidelines – AAPOnly for High Risk Infants
2008 No dietary restrictions during pregnancy or
lactation Exclusive breastfeeding for 6 months If bottle-fed use extensively hydrolyzed
formulas Solids at 4 to 6 months, no evidence to
support delayed introduction of foods considered to be allergenic
Is Waiting Better?
Israeli population and peanuts Swedish population and fish German GINI study
Take Home Messages
Encourage exclusive breastfeeding for 6 months (WHO guidelines)
If bottle-feeding use extensively hydrolyzed formula if high risk infant
Avoid introduction of solid foods until 4-6 months of age
Stay tuned, this isn’t the end of the story!
ReferencesGarcia-Careaga et al. Gastrointestinal Manifestations of Food
Allergies in Pediatric Patients. Nutr in Clin Prac 20:526-535, 2005.
Herman, P & Drost, L. Evaluating the Clinical Relevance of Food Sensitivity Tests: A Single-Subject Experiment. Alt Med Review 9(2):198-207.
Joneja, J. Food Allergy in Adults. Dietitians of Canada Current Issues, 2007.
Joshi et al. Interpretation of Commercial Food Ingredient Labels by Parents of Food-Allergic Children. Ann Allergy Asthma Immunol 90:84-89, 2003.
Muraro et al. Dietary Prevention of Allergic Diseases in Infants and Small Children. Pediatr Allergy Immunol 15:291-307, 2004.
Pyrhonen et al. Occurrence of parent-reported food hypersensitivities and food allergies among children aged 1-4 yr. Pediatr Allergy Immunol 20:328-338, 2009.
Wennergren, G. What if it is the other way around? Early introduction of peanut and fish seems to be better than avoidance. Acta Paediatrica 98:1085-1087, 2009.