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An Approach to Food Allergies
Edmond S. Chan, MD, FRCPC
Clinical Associate Professor, UBC
Division of Allergy & Immunology
June 7, 2014
BCCFP Spring 2014 Family Medicine Conference
Vancouver
Faculty/Presenter Disclosure
• Faculty: Edmond Chan
• Relationships with commercial interests:
• Advisory board: Sanofi (Allerject)
• Honoraria (CME lectures): Sanofi, Pfizer, Mead Johnson, Nestle
CFPC CoI Templates: Slide 1

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Disclosure of Commercial Support
• This program has not received financial support.
• This program has not received in-kind support.
• Potential for conflict(s) of interest: None
CFPC CoI Templates: Slide 2
Mitigating Potential Bias
• There is no potential bias with any products.
CFPC CoI Templates: Slide 3

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Objectives
• Discuss: How to diagnose food allergies
• Examine: How to manage non-acute food
allergies
• Review: Update on the prevention of food
allergy
Case: 4 year old girl
• Older brother with confirmed, multiple IgE mediated
food allergy and eczema
– Girl has mild eczema, parents afraid to introduce
allergenic foods
• Mom paid for IgG blood tests via alternative health
practitioner 2 yrs ago: egg specific IgG blood test
negative
– mom gave egg at home & girl had anaphylaxis
• Currently: egg specific IgE negative
• Approach?

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What does “food allergy” really mean?
• ADVERSE REACTION to food=any abnormal reaction, due
to:
• I) TOXIC
– Bacterial enterotoxins
– Other food poisonings
• II) NON-TOXIC
– 1. “Food Allergy” = Immune mediated
– 2. Food Intolerance = Non-immune
Johansson S, EAACI, Allergy 2001; 56:813-24
Definitions, cont’d
• 1. “Food Allergy”
– IgE mediated (e.g. anaphylaxis, oral allergy syndrome)
– Mixed IgE/non-IgE (e.g. eosinophilic esophagitis)
– Non-IgE (e.g. Protein induced enterocolitis)
• 2. Food Intolerance
– Enzyme deficiency (e.g. lactase deficiency)
– Pharmacologic sensitivity (e.g. caffeine)
– Psychologic (e.g. food aversion)
Johansson S, EAACI, Allergy 2001; 56:813-24

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IgE mediated Food Allergy: Suspected
foods
• Majority of IgE mediated reactions due to these foods:
– Cow’s milk*
– Egg*
– Peanut* & Tree nuts
– Sesame seed
– Fish & Shellfish
– (Soy)
– (Wheat)
Predictive values for skin tests
• Positive predictive value low unless recent and
clear history
– “Asymptomatic sensitization”
• Negative predictive value high
• i.e.) negative results more useful than positive
ones
– Guidelines for the Diagnosis and Management of Food Allergy in the
U.S. J Allergy Clin Immunol 2010; 126:S1-S58

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Predictive values for serum specific IgE
• Positive predictive value low unless recent and
clear history
– “Asymptomatic sensitization”
• Negative predictive value high
• i.e.) negative results more useful than positive
ones
– Guidelines for the Diagnosis and Management of Food Allergy in the
U.S. J Allergy Clin Immunol 2010; 126:S1-S58
PREDICTIVE VALUES FOR COMMON FOODS, Specific IgE blood
tests
Sampson HA, J Allerg Clin Immunol, 2004;113:805-19

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Oral Food Challenges
• The gold standard in the allergist’s evidence
based approach
• For ruling out food allergy
• For the follow-up of food allergy
(?outgrowing)
– Generally done when specific IgE levels fall to a
level at which ~50% tolerate the food
Sicherer SH & Bock SA. J Allergy Clin Immunol 2006;117:1419-22
• …positive test results for food-specific IgG are to be
expected in normal, healthy adults and children
• The CSACI strongly discourages the practice of food
specific IgG testing for the purposes of identifying or
predicting adverse reactions to food

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Objectives
• Discuss: How to diagnose food allergies
• Examine: How to manage non-acute food
allergies
• Review: Update on the prevention of food
allergy
Management of allergic conditions
• Allergen avoidance
• Medical management
• Immunotherapy (where indicated)

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Egg allergy: eat baked goods
regularly?
• 1. May result in outgrowing egg allergy earlier
– Via tolerance induction
• 2. Possible improved quality of life
• 3. Often, children are already eating
occasionally, and message is then to increase
to daily ingestion
Dietary baked egg accelerates resolution of egg
allergy in children
• Prospective, 79
subjects, baked oral
challenges, 37.8
month F-up, usual
recipe, control
• Egg tolerance
median 50.0 vs 78.7
mo (p<.0001)
• IgE↓ , IgG4↑
Leonard SA, Sampson, Sicherer et al. JACI 2012

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Egg allergic children not currently
eating baked goods
• Recent evidence suggests 70-80% of children
with egg allergy tolerate baked goods
• Difficult to predict the 20-30% who will react if
not currently eating already
– History, skin tests, and specific IgE blood tests do
not reliably correlate with chance of reacting if not
currently eating
• Decision to offer oral challenge individualized
2013 Bartnikas L, Schneider L et al, JACI IP
Intramuscular flu vaccine can be safely
given to those with egg allergy
• Canadian multi-centre study:
– 367 patients recruited (132 severe egg allergy)
– Analyzed with other studies, total 4172 patients
(513 severe egg allergy)
– None had anaphylaxis
Des Roches A et al. J Allergy Clin Immunol. 2012 Nov;130(5):1213-1216

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Case: 6 year old boy
• History of peanut and tree nut allergy
• Has been carrying an Epipen Junior since 2 yrs of age
• Child is now 21 kg
• MD writes prescription for Epipen Regular 0.3mg
• Pharmacist faxes back with message that monograph
for Epipen says to use 0.3mg only for 30kg or more
• What to do next?
Only 2 doses of epinephrine
autoinjectors
• Balance of efficacy & safety
• 0.3mg (Epipen or Allerject)
– 25kg children
– 20kg children at higher risk (asthma)
• 0.15mg (“Junior”)
– 10-25kg children
– Often prescribed for “less than 10kg” due to lack
of alternatives
Sicherer SH and Simons FER. Pediatrics 2007;199(3), 638-46

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• Randomized, controlled crossover trial
• Primary outcome of ‘desensitization’ at 6 months
(passed oral challenge)
– 62% in active group, 0% in control group
• 84% of the active group tolerated 800mg peanut
protein daily (~ 5 peanuts)
• Side effects mild in majority
Oral food immunotherapy not ready for
clinical use yet
• Safety: anaphylaxis risk variable in studies,
?eosinophilic esophagitis risk
• Efficacy: short term ‘desensitization’ versus
long term ‘tolerance’?
– No standard protocol
– Some data for return of cow’s milk allergy after
therapy
• Cost effectiveness?
• More studies needed
Greenhawt MJ. Lancet 2014;383:1272-4

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Objectives
• Discuss: How to diagnose food allergies
• Examine: How to manage non-acute food
allergies
• Review: Update on the prevention of food
allergy
Case: 3 month old boy
• History of atopic dermatitis
• 5 yo brother with severe anaphylaxis to
peanut, atopic dermatitis, severe asthma
• Mom asks you…
– Should I introduce peanut to Billy?
– If yes, then…Why?
• When? Where? How?
– “He could get anaphylaxis the first time”
• Am I putting Mike in danger?

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CPS Position Statement Dec 2, 2013
• Chan ES, Cummings C. Dietary exposures and
allergy prevention in high-risk infants.
Paediatr Child Health 2013;18(10):545-9
– www.cps.ca/documents/position/dietary-
exposures-and-allergy-prevention-in-high-risk-
infants
• Joint statement of the CPS and the CSACI
(Canadian Society of Allergy & Clinical
Immunology)
Canadian Family Physician,
April 2014 issue

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Defining risk
• An infant at high risk for developing allergy
usually has
– a first degree relative (at least one parent or
sibling) with an allergic condition such as atopic
dermatitis, food allergy, asthma, or allergic rhinitis
– While recommendations are intended for high-risk
infants, some of the studies cited included infants
from the general population not considered high
risk
CPS Position Statement
Recommendations
• 1. Do not restrict maternal diet during pregnancy or
lactation
• 2. Breastfeed exclusively for the first six months of
life
• 3. Choose a hydrolyzed cow’s milk based formula for
mothers who cannot or choose not to breastfeed
– Extensively hydrolyzed casein likely more effective
than partially hydrolyzed whey

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CPS Position Statement
Recommendations
• 4. Do not delay the introduction of any specific solid
food beyond six months of age
– Includes non-choking forms of peanut, egg, fish, etc
– Delay does not prevent and may increase risk of food
allergy
• 5. More research is needed on inducing tolerance
via early introduction between 4 to 6 months of age
CPS Position Statement
Recommendations
• 6. Once introduced, regularly ingest the food (e.g.
several times/week) to maintain tolerance
– Routine skin or specific IgE blood testing before a first
ingestion is discouraged due to the high risk of potentially
confusing false-positive results

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Lack G. J Allergy Clin Immunol 2012; 129:1187-97
Clinical Teaching Pearls #1
• DIAGNOSIS
– History is the most important “test”
– Skin prick or specific IgE testing is susceptible to
false positive results unless history of recent
immediate reaction
– Food-specific IgG testing to diagnose a food allergy
is inappropriate, not evidence based, & strongly
discouraged

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Clinical Teaching Pearl #2
• NON-ACUTE MANAGEMENT
– Eating baked goods with egg may help with
outgrowing egg allergy faster
– Intramuscular flu vaccine is safe for egg allergy
– Switch from the 0.15mg (“Junior”) epinephrine
auto-injector dose to the 0.3mg (“Adult”) dose
when a child reaches 20-25kg weight
– Oral immunotherapy to food is not ready for
clinical use
Clinical Teaching Pearls #3
• PREVENTION
– Do not delay introduction of any solid food
beyond 6 months of age
– Once introduced, eat regularly (e.g. several
times/week)