+ Module Content Definitions Food allergy vs. food intolerances Physiological responses to food allergens Symptoms of food-induced allergic reactions Diagnosis of food allergies Instructional video
+ Definitions Food “any substance—whether processed, semi- processed, or raw—that is intended for human consumption and includes drinks, chewing gum, food additives, and dietary supplements” “substances used only as drugs, tobacco products, and cosmetics (such as lip-care products) that may be ingested are not included” (Boyce et al., 2010, p. S8).
+ Definitions Food Allergy “an abnormal response to a food, triggered by the body’s immune system” “an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food” (Boyce et al., 2010, p. S8).
+ Definitions Allergic response “a reproducible adverse reaction to a substance mediated by an immunological response. The substance provoking the reaction may have been ingested, injected, inhaled, or merely have come into contact with the skin or mucous membranes” (David, 2000, p. 34)
+ Definitions Food intolerances non-immunologic adverse reactions Intolerance symptoms are usually caused by an inability to digest or metabolize a food, resulting in gas production, cramping, or diarrhea. Lactose intolerance (inability to digest milk sugar) is the most common type of food intolerance”(Boyce et al., 2010, p. S9).
+ Definitions IgE (Immunoglobulin E) a unique class of immunoglobulin that mediates an immediate allergic reaction (Boyce et al., 2010). IgE is released from plasma cells in the mucosa of the GI (gastrointestinal) tract, respiratory tract, and tonsils when the immune system overreacts to an allergen, triggering the release of histamine, inflammation, and an allergic responses (Marieb & Hoehn, 2010).
+ Food allergy vs. food intolerances Both food allergies and food intolerance are types of adverse reactions to food. How and why symptoms develop, however, differs. Food allergies, “an abnormal response to a food, triggered by the body’s immune system” (Boyce et al., 2010, p. S8), occurs when the body mistakenly recognizes some part of food as an antigen (FARE, 2014). Subsequently, immune responses will occur that involve IgE, and the body reacts with the systematic release of histamine. Food intolerances, on the other hand, are non-IgE-mediated adverse reactions to food due to the lack of enzymes (e.g., lactose intolerance) or other irritant or toxic mechanisms. Two common food intolerances are lactose intolerance and gluten intolerance.
+ Lactose intolerance Individuals with lactose intolerance lack lactase, the enzyme that break down lactose, and experience excessive fluid production in the GI tract, resulting in abdominal pain and diarrhea. Similar intolerance can be observed when a person has hereditary fructose intolerance, the deficiency in fructose bi-phosphate aldolase, a liver enzyme (David, 2000). A person with this with hereditary fructose intolerance may experience an inability to digest the sugar fructose.
+ Gluten intolerance Celiac disease is caused by an adverse reaction to gluten (FARE, 2014). If individuals with gluten intolerance accidentally ingest gluten, they experience severe abnormal pain and diarrhea (which can occur up to six hours after food is eaten). Other symptoms include bloating, abdominal discomfort or muscular disturbances, and bone or joint pain. Individuals with gluten intolerance should avoid wheat, barley, rye, oats, and common cereal products that contain various amounts of gluten.
+ Definition Gluten intolerance Foods to avoid Wheat Barley Rye Oats Common cereal products that contain various amounts of gluten
+ Types of adverse reaction to food (Boyce et al., 2010)
+ Comparison of Food Allergies and Food Intolerances Food AllergyFood Intolerance Body systemSkin Cardiovascular Gastrointestinal Onset of symptoms A few seconds to hours after ingestion Slow onset Immunological mechanism Antibody (IgE)None Non- immunological mechanism NoneLack of enzymes (e.g., lactase) Amount of food to trigger a reaction Dose varies depending on individuals; may be triggered by one molecule of food allergen Dose varies depending on individuals
+ Physiological responses to food allergens Immediate hypersensitivity reactions: IgE-mediated reactions The actions will be heightened when a person with a food allergy ingests food allergens. Symptoms may occur for up to two hours after ingestion of an allergen Immediate responses are inflammatory responses due to the cross-linking of two IgE antibodies.
+ Physiological responses to food allergens Delayed hypersensitivity reactions: Cell-mediated reactions The actions develop from 6 to 24 hours after ingestion of an offending food. Different immune cell types, such as t-cells, macrophages, and eosinophils, are involved in this type of reaction. Localized tissue damage can occur due to inflammation.
+ Symptoms of food-induced allergic reactions Usually, food allergy symptoms begin within two hours of eating a food. Symptoms may appear hours after eating, though this is rare (Chafen et al., 2010). Symptoms of food allergies can manifest in many systems, including the cutaneous, GI, and cardiovascular systems.
+ Symptoms of food-induced allergic reactions most common symptoms hives wheezing a hoarse voice
+ Animation of an IgE-mediated allergic reaction
+ SUMMARY Both food allergies and food intolerances are types of adverse reactions to food. How and why symptoms develop, however, differs. The most common symptoms of food-induced allergic reactions are hives, wheezing, and a hoarse voice. Six steps are required to correctly diagnose food allergies (NIAID) (2012): 1) Detailed history 2) Diet diary 3) Elimination diet 4) Skin prick test 5) Blood test 6) Oral food challenge