Module 5: Food Allergies and Intolerances

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4. Jun 2010

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Module 5: Food Allergies and Intolerances

  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
  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: Anaphylaxis Canada: Canadian Celiac Association: Canadian Food Inspection Association: Canadian Paediatric Society: Canadian Society of Allergy and Clinical Immunology: 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):
  38. Professional & Parent Resources Dietitians of Canada Practice-based Evidence in Nutrition (PEN): Eat Right Ontario: Food Allergy & Anaphylaxis Network: Food Allergy News: Medic-Alert: Specialty Food Shop: 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
  39. Acknowledgements This presentation was adapted from: Understanding Food Allergy – A Primer for Dietitians (International Food Information Council), October 2007 and Food Allergies in Canada: Dietetic and Nutritional Management (Janice Joneja), December 2007. Content revisions and updates by Jane Lac, RD Consultant