This document provides an overview of food allergies for dietitians, including distinguishing allergies from intolerances, common food allergens, symptoms of allergic reactions, diagnosis, and management. It discusses the immune system response to allergens and introduces concepts such as oral tolerance. Statistics on the prevalence of food allergies in children and adults are presented. The roles of dietitians in supporting diagnosis and managing allergies through dietary avoidance and ensuring nutrition are also summarized.

1. A Preschool Nutrition
Primer for RDs
Food Allergies and
Intolerances
Nutrition Screening Tool
for Every Preschooler
Évaluation de l’alimentation
des enfants d’âge préscolaire

2. Learning Objectives
Distinguish food allergy from other adverse food
reactions.
List the nine common food allergens according to
Health Canada.
Understand medical diagnosis and management of
food allergy (including symptoms and tests) in order
to communicate effectively with the client and
attending physician.
Understand the appropriate dietary management of
food allergy, including allergen avoidance and
ensuring nutritional adequacy.
List high-risk situations for allergic individuals.
List strategies for avoiding allergenic proteins in
foods.

3. Presentation Outline
Introduction to Food Allergies
Allergy versus Intolerance
The Immune System
Reactions to an Allergen
Diagnosis of a Food Allergy
Managing Food Allergies
Prevention/Delaying Allergic Disease
Health Canada Regulations on Allergen
Food Labeling
Practice Questions
References

4. Introduction to
Food Allergies
Also known as hypersensitivity.
Immune system response to the protein in foods.
Body recognizes protein as a foreign substance
and produces a number of responses (allergic
reactions).
Reaction is not dose dependent.
Common food allergies in children: eggs, soy,
milk, wheat, seafood (shellfish,fish), peanuts,
tree nuts, and sesame (sulphites).
Common food allergies in adults: peanuts, tree
nuts, shellfish, and fish.

5. Statistics of Food Allergies
Nearly 4% of North Americans have food
allergies, many more than recorded in the past.
Incidence of food allergy much higher in
children (>8%) than adults (<2%).
Prevalence of some food allergies doubled in
American children younger than 5 years of age
in the past 5 years.
Many food allergens have been characterized at
the molecular level, leading to increased
understanding of the causes of many allergic
disorders.

6. Incidence of Food Allergy
Prevalence highest in infants and toddlers.
Cow’s milk allergy incidence: 2.5% of infants.
Up to 8% of children under 3 years have allergy
to a limited number of foods:
Cow’s milk
Wheat
Egg
Shellfish
Fish
Soy
Peanut
Tree nuts

7. Incidence of Food Allergy
Over 170 foods have been documented as
causing food allergy.
90% of food allergies in children are due to:
- Milk - Soy - Peanut
- Egg - Wheat
85% of food allergies in adolescents and adults
are due to:
- Peanut - Fish
- Tree nuts - Shellfish

8. Priority Food Allergens
in Canada
Peanuts
Tree nuts (almonds, brazil nuts, cashews, hazelnuts (filberts),
macadamia nuts, pecans, pinenuts, pistachios, walnuts).
Sesame seeds
Milk
Eggs
Fish
Shellfish (e.g. clams, mussels, oysters, scallops and
crustaceans such as crab, crayfish, lobster, shrimp).
Soy
Wheat
Sulphites
These Priority Allergens account for more than 95% of severe
adverse reactions related to food allergens.

9. Allergy versus Intolerance
Food Allergy Food Intolerance
An immune response to an ingested A generic term describing an
food or food additive that contains a abnormal physiological response to an
protein or a molecule linked to a ingested food or food additive which is
protein not a result of an immune response
Reaction is not dose-dependent Does not require “priming”
Requires a “sensitizing event” that Reaction is dose-dependent:
primes the immune system for future symptoms are dependent on amount
response and frequency of consumption
Allergic potential is an inherited Reaction is sometimes inherited, but
characteristic (is idiosyncratic) not always

10. Examples of Food
Intolerances
Lactose intolerance:
Deficiency of lactase
Sucrose intolerance:
Deficiency of sucrase
Sulphite intolerance:
Possibly deficiency of sulphite oxidase

11. Examples of Food
Intolerances
MSG sensitivity
Mechanism unknown
Sensitivity to food additives
Various mechanisms
Sensitivity to biogenic amines
Tyramine
Histamine

12. What is Celiac Disease?
A hypersensitivity to gluten
a protein found in wheat, barley, rye, and certain
other grains.
Chronic inflammatory disorder of small intestine.
Cell-mediated allergic response.
May also include dermatitis herpetiformis
a chronic skin disorder caused by an IgA-
mediated hypersensitivity to gluten.

13. Celiac Disease
Celiac is often confused with other ailments
irritable bowel syndrome, Crohn’s disease, etc.
GI symptoms: gas, abdominal bloating and pain,
diarrhea, steatorrhea, mouth sores.
Skin symptoms: dermatitis herpetiformis.
Potentially asymptomatic, increasing risk for
malnutrition-related symptoms and
complications.

14. The Immune System
Designed to protect the body from invasion by
foreign materials.
T cell lymphocytes detect foreign proteins
(antigens) in any form.
T cells then trigger a series of immunological
reactions, mediated by cytokines.

15. The Immune System
All foods contain proteins – derived from plants
and animals – all of which are foreign to the
human body.
In order for food to be absorbed, metabolized,
and utilized by the body, the immune system
needs to be “educated” that the foreign material
is safe.
This involves a complex series of immunological
reactions.

16. The Immune System
Oral Tolerance
In most cases this results in “education” of the
T cells to not respond to that food protein when
it enters via the oral route called oral tolerance.
Contrasts with the active immune responses
needed to protect the gut against continual
bombardment by invading pathogens and their
products (toxins, etc).

17. The Immune System
Food allergy occurs as a result of lack of
tolerance.
T cells respond as if the food were a threat to
the body.
Antibodies are produced specifically to reject the
food – called sensitization.
Inflammatory mediators are released to defend
the body.
Mediators act on body tissues to cause the
symptoms of allergy.

18. Inflammatory Chemicals in the
Allergic Reaction
Preformed:
Histamine E
Enzymes
Chemo-attractants
Newly formed
Prostaglandins
Leukotrienes
Each chemical has a different effect on tissues:
the allergic response is the combined effect of
them all.

19. Symptoms of Food Allergy
http://www.cfsan.fda.gov/~dms/wh-alrg1.html

20. Symptoms: GI Tract
Swelling or itching of the lips, mouth and/or
throat.
Nausea, vomiting, cramping and/or diarrhea.
Eosinophilic esophagitis/gastroenteritis may be
associated with food allergic responses
Critical nutrition management role for dietitian.

21. Symptoms: Skin
Itching, swelling, hives, eczema and/or redness.
Up to 20% of acute hives are caused by food
allergy; hives lasting more than six weeks are
rarely caused by food allergy.
37% of children with moderate to severe atopic
dermatitis also have food allergy.

22. Symptoms: Respiratory Tract
Congested, runny, and/or itchy nose, sneezing,
raspy cough, and/or wheezing.
Nasal symptoms occur in 25-80% of food
allergic patients; in isolation, usually not food-
related.
Asthma is food-related in only 5.7% of asthmatic
children.
Heiner Syndrome
Rare adverse pulmonary response to cow’s milk.
Can occur in a very small percentage of infants.

23. Symptoms: Anaphylaxis
Serious allergic reaction, and can be life-
threatening.
Affects multiple body systems: skin, respiratory,
GI tract and cardiovascular.
Anaphylactic shock: “an explosive overreaction
of the body's immune system to an allergen”.
Symptoms include swelling, difficulty breathing,
abdominal cramps, vomiting, diarrhea,
circulatory collapse, coma and death.

24. Symptoms: Anaphylaxis
Food is the most common cause of anaphylaxis.
Other causes could be from insect stings,
medicine, latex, or exercise.
1-2% of Canadians live with the risk of an
anaphylactic reaction.
Treatment: Epinephrine (adrenaline) shot.

25. Symptoms: Anaphylaxis
Anaphylaxis is a growing public health issue.
Fatalities are rare and usually avoidable.
Measures must be in place to reduce the risk of
accidental exposure and to respond
appropriately in an emergency
Improved patient self management.
Comprehensive school board policies.
Standardized school anaphylaxis plans.
Greater community support and involvement.

26. Diagnosis of a Food Allergy
Managed by primary care physician or board-
certified allergist.
Includes complete medical history and physical
exam.
May include food diary, completed by patient.
Screening Tools
Skin Prick Test
Blood Tests

27. Diagnosis of a Food Allergy
Elimination diet
Food challenge
Diagnosis involves both science and clinical
judgment!
Periodic re-evaluation

28. Dietitian’s Role
Refer a patient to their primary care physician
or a board-certified allergist.
Support physician/allergist during diagnosis by
assisting with:
Food Diary
Food Challenge
Elimination Diet

29. Managing Food Allergy
Avoid the allergen-containing food(s)!
Develop a Food Allergy Action Plan
Inform and involve family, friends, and
caretakers.
Early symptom recognition
Emergency therapy: Epinephrine (adrenaline).
Medical identification necklaces/bracelets.

30. Managing Food Allergy
Infants
Formula feeding
Hypoallergenic milk or soy based formula may be
indicated.
Breastfeeding
Maternal dietary restrictions may be needed.
Communication
Sharing information with others who provide and
prepare food.

31. Managing Food Allergy
Education:
Be able to identify the allergenic food and alternative
names for the allergen.
Avoid foods likely to contain, or be contaminated by the
allergen
Be aware of all terms on food labels that would indicate
the possible presence of the food.
Carry injectable adrenalin, and be familiar with its use in
case of accidental exposure reaction.
Wear a MedicAlert tag or bracelet in case of loss of
consciousness in an allergic reaction.

32. Managing Food Allergy
Education
High-risk situations
Cross-contact
Nutritional adequacy

33. Preventing/Delaying
Allergic Disease
High-risk: Infants with family history.
Breastfeeding
Verdict is still out.
Some evidence of correlations between
breastfeeding and reduced incidence of food
allergy and asthma.
CPS strongly recommends exclusive
breastfeeding for the first 6 months of life for
healthy, term infants.

34. Preventing/Delaying
Allergic Disease
New AAP Clinical Report (2008)
Current evidence does not support:
dietary restrictions during pregnancy or lactation.
delaying introduction of allergen foods after 4-6
months of age to prevent atopic disease.
High risk infants may still benefit from nutritional
intervention and delayed introduction of allergen foods.
Breastfeeding is still recommended exclusively for the
first 6 months.
High risk infants may be fed hydrolyzed formula versus
cow’s milk formula to prevent/delay onset of food allergy.
Positive effects on eczema from delayed introduction of
solids; evidence is conflicting.

35. Allergen Labelling in Canada
Health Canada is in the process of updating allergen
labeling regulations:
To include ingredients such as flavours, flour,
seasoning and margarine.
Currently, not required to list these components
Food allergens that must be included in labels:
peanuts, tree nuts (almonds, Brazil nuts, cashews,
hazelnuts, macadamia nuts, pecans, pine nuts,
pistachio nuts and walnuts), sesame seeds, milk,
eggs, fish, crustaceans, shellfish, soy and wheat.
mustard will be added to this list.
Onion and garlic not included on food labels.

36. Allergen Labelling in Canada
Other amendments include:
Gluten sources declared when food contains gluten
protein or modified gluten protein from barley, oats,
rye, triticale or wheat, including kamut or spelt.
Sulphites declared when added directly to a food or
when the total amount contained in the food is greater
than 10 ppm.
Comments from the regional consultation workshops
for the proposed amendments were submitted in
February 2010. Final regulations will be published in
the near future.

37. Professional & Parent
Resources
Allergy & Asthma Information Association: www.aaia.ca
Anaphylaxis Canada: www.anaphylaxis.ca
Canadian Celiac Association: www.celiac.ca
Canadian Food Inspection Association:
www.inspection.gc.ca
Canadian Paediatric Society: www.cps.ca
Canadian Society of Allergy and Clinical Immunology:
www.csaci.medical.org
Dealing with Food Allergies in Babies and Children. J. M.
Vickerstaff Joneja, PhD, RDN. Publisher: Bull Publishing
Company; 2007. ISBN: 978-1933503-05-9.
Dietitians of Canada Paediatric Nutrition Network (DCPNN),
Vol 8 (#2): www.dietitians.ca/networks/pediatric.asp

38. Professional & Parent
Resources
Dietitians of Canada Practice-based Evidence in Nutrition
(PEN): www.dieteticsatwork.com
Eat Right Ontario: www.eatrightontario.ca
Food Allergy & Anaphylaxis Network: www.foodallergy.org
Food Allergy News: www.foodallergynews.com
Medic-Alert: www.medicalert.com
Specialty Food Shop: www.specialtyfoodshop.ca
Winnipeg Regional Health Authority Child Health Pediatric
Enteral and Parenteral Nutrition Handbook (2nd ed, Dec
2008). Author/Editor: Pat Ozechowsky (RD, CNSD).
Department of Nutrition and Food Services. Contact
Information: (204) 787-1447 or cginter@hsc.mb.ca

39. Acknowledgements
This presentation was adapted from:
Understanding Food Allergy – A Primer for
Dietitians (International Food Information
Council), October 2007
http://www.ific.org/adacpe/foodallergycpe.cfm
and Food Allergies in Canada: Dietetic and
Nutritional Management (Janice Joneja),
December 2007.
Content revisions and updates by Jane Lac, RD
Consultant Janelac.work@gmail.com