Transcript Allergy - McMaster Faculty of Health Sciences

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)
b)
c)
d)
<10%
10-20%
20-30%
>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
Birch
Ragweed
Grass pollen
Food Allergen
Apples, pears, celery,
hazelnuts, kiwi,
potatoes, carrots
Melons (includes
cucumbers) and
bananas
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
IgG ELISA (variety of
Testing Technique
Serum sample
specific tests e.g. IgG4)
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)
b)
c)
Casein
Lecithin
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 – AAP





Only 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 – AAP
Only 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 46 months of age
 Stay tuned, this isn’t the end of the
story!

References
Garcia-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.