Amy Simonne, Ph.D. Assistant Professor FYCS University of Florida Food Allergies…101 Amy Simonne, Ph.D. Assistant Professor FYCS University of Florida Food, Nutrition and Health Update 2002, Feb 12, 2002
Outlines Statistics What is food allergy Immunology concepts What foods causes allergies Possible ways to deal with food allergy Resources for food allergies
How prevalence is food allergy? Experts agree that allergies in developed countries are becoming more common. In the U.S., food allergies afflict 2-2.5% adults and 6-8% children. 100-175 people in the U.S. die each year. Death generally result from anaphylactic shock, often to peanuts or tree nuts. More than 160 foods have been associated with allergic reactions. C&EN/January 7, 2002 page 21.
What is food allergy? Food allergy is an inappropriate immune response to an otherwise harmless food. True food allergy involves several types of immunological responses. Food allergens are usually proteins. Proteins in some individuals are recognized by the immune system as foreign invaders.
Types of food allergies Immediate hypersensitivity occurs within minutes to a few hours after ingestion of offending foods. Systemic: Itching, urticaria (hives), Vomiting, Abdominal cramps, diarrhea and respiratory distress, and in severe cases anaphylactic shock Localized: hives and eczema or atopy (an umbrella term covering clinical presentations of food allergy etc) Delayed hypersensitivity reactions (>8hours after ingestion)
Understanding Immunological concepts Human body has many defense mechanisms to fight off infectious diseases and other toxic foreign substances. Strong healthy adult human can fight off most of infectious diseases. Ability to fight off disease can be modulated by genetics, age, race and lifestyles (diets, exercise and amount of sleep etc.)
Terminology Allergic reactions are Antigen-Antibody reactions Antigen = a foreign substance Antibody = a protein produced in response to an antigen that is capable of binding specifically to the antigen!
Understanding Immunological concepts Human body has two categories of defense system Non specific defenses Physical barriers (skin and mucous membrane) Chemical barriers (saliva, mucus, gastric juices etc) Inflammation (reddening, swelling and temperature increase of the affected sites) Fever (elevated body temperature) Specific defenses or specific immunity** Antibodies (many kinds of antibodies for many kinds of antigens)
Understanding Immunological concepts Food allergies is related to specific defenses or specific immunity Immune literary means “free of burden” Actions of the immune system are triggered by antigens (foreign substances). Most antigens are large protein molecules; Some antigens are polysaccharides and few are glycoproteins (carbohydrate and protein) or nucleo-proteins.
Symptoms-Food Allergy* Nausea Diarrhea Abdominal cramps Pruritic rashes Angioedema Asthma/rhinitis Vomiting Hives Laryngeal edema Anaphylaxis * Exercise exacerbates symptoms
What are common allergenic foods? Legumes (Peanuts and Soybeans) Mollusks (snails, mussels, oysters, scallops, clams, squid) Milk Eggs Fish (cod, salmon, haddock etc) Crustacea (shrimp, crawfish, lobster etc.) Wheat Tree nuts (almonds, walnuts, Brazil nuts etc) Selected food additives
It is not easy…living with food allergies! What would you choose to eat, if you are allergic to milk or dairy products?
Hidden food ingredients in ready made food products! Milk and milk product derivatives Egg and egg derivatives Peanuts, tree nuts and derivatives Fish derivatives (surimi, fish sauce, fish paste etc) Soy and its derivatives
Cross-Reactions: Food and non-food allergens Ragweed- Watermelon, cantaloupe, honeydew, bananas Mugwort- celery Birch pollen-carrots, apples, hazelnuts, potatoes Banana – latex * If allergic to one shellfish or legumes, likely allergic to all!
Common medications prescribed by doctors epinephrine (relaxes smooth muscle, constricts blood vessels, and stimulates the heart; used for severe systemic reactions); antihistamines (block the binding of histamine to histamine receptors on target cells)
Other types of food allergy, Non-IgE Mediated: Immune Complex-mediated Symptoms usually gastrointestinal Delayed type hypersensitivity
How about food intolerance? Direct effect of food Enzyme deficiency (e.g., lactase, sucrase etc) Symptoms of food intolerance: bloating, cramping, gas and diarrhea Main cause of food intolerance: carbohydrates (lactose, fructose, sorbitol)
Resources for food allergies Food Allergy and Anaphylaxis network (FAAN) Other resources See handouts