Food Allergies and Intolerances Unit 17

Food Allergy Food allergies are a major health concern in the US and other Westernized countries Food allergy (food hypersensitivity) Adverse reaction to a normally harmless substance in food that involves the body’s immune response

Adverse Reactions to Foods Food intolerance Adverse reaction to a normally harmless substance in food that does not involve the immune system Immune system Body tissues that provide protection against bacteria, viruses, and other harmful substances

Adverse Reactions to Foods Foods that often cause adverse reactions:

Allergy and the Immune System In people with allergies, body cells identify some components of food as harmful and trigger the body’s immune system Food allergen Substance in food (usually protein) that the body identifies as harmful and that elicits an allergic reaction from the immune system

Allergy and the Immune System In response to an allergen, the immune system forms antibodies Antibodies Proteins the body makes to fight harmful invaders such as viruses, bacteria, or (in the case of food allergies) allergens

Allergy and the Immune System Antibodies are formed on first exposure to an allergen – when the allergen reappears, an allergic reaction occurs Histamine Substance released in allergic reactions Causes blood vessel dilation, itching, hives, drop in blood pressure, release of stomach acids Counteracted by antihistamines

Development of Allergic Reaction

Food Allergy Symptoms

Anaphylactic Shock In highly sensitive people, exposure to trace amounts of an allergen can cause anaphylactic shock – a massive immune reaction that can result in death

Key Terms Anaphylactic shock Reduced oxygen supply to the heart and other tissues due to the body’s reaction to an allergen in food or other “foreign” substance Symptoms may include abdominal cramps, vomiting, chest tightness, paleness, weak and rapid pulse, difficulty breathing Can result in death Treated with epinephrine injection

Foods Most Likely to Cause Allergy Food ingredient labels are required to state whether a food contains one or more of the “big eight” food allergens Nuts Eggs Wheat Milk Peanuts Soy Shellfish Fish

Foods Most Likely to Cause Allergy

Wheat Allergy (Celiac Disease) Celiac disease (celiac sprue or gluten sensitive enteropathy) An autoimmune disease characterized by inflammation of the small-intestine lining resulting from a genetic gluten intolerance Causes diarrhea, fatty stools, weight loss, vitamin and mineral deficiencies Treated with gluten-free diet

Gluten in Foods

How Common Are Food Allergies? 5% of infants and children develop a food allergy, often to cow’s milk or egg white For children at risk: No cow’s milk before age 1 No eggs before age 2 No peanuts, nuts, fish, shellfish before age 3

How Common Are Food Allergies? 2-3% of adults have food allergies, and the number is increasing About 1/3 of Americans believe they have food allergies – but usually, allergy is not confirmed by testing

Diagnosing Food Allergy Double-blind, placebo-controlled food challenge Test used to determine the presence of a food allergy or other adverse reaction to a food Neither patient nor care provider knows whether the suspected food or a placebo is being tested Undertaken under medical supervision

Other Tests for Food Allergy Immunoglobin-E test IgE protein produced in response to an allergen Doesn’t identify allergen Skin prick tests For absence of food allergy only – positive results don’t prove an allergy exists Positive skin-prick test

Bogus Tests Companies that offer food allergy tests through the mail do not use reliable techniques and are a waste of money Other unreliable tests: Hair analysis, cytotoxic blood tests, iridology, sublingual food injection provocation

Treating Food Allergies Allergy shots for food allergens are not yet available After an allergy is confirmed, the only treatment is to eliminate the food from the diet

Food Intolerances Food intolerance does not involve the immune system Produces reactions similar to food allergy, but by different mechanisms

Lactose Maldigestion Lactose maldigestion Characterized by reduced digestion of lactose due to low availability of the enzyme lactase Occurs in 25% of US adults; incidence varies by population group Results in lactose intolerance

Lactose Intolerance Lactose intolerance GI symptoms resulting from consumption of more lactose than can be digested with available lactase Flatulence, bloating, abdominal pain, diarrhea, “rumbling in the bowel” due to breakdown of undigested lactose by intestinal bacteria Restricts intake of lactose-containing products

Sulfite Sensitivity Sulfite is a food additive (preservative) used in many foods and medications Small amounts can cause anaphylactic shock in sensitive people

Red Wine, Aged Cheese, and Migraines Histamine in some foods may cause migraine headaches in sensitive people Red wine, beer, sardines, anchovies, cured sausages, pickled cabbage, spinach, catsup Tyramine may cause similar symptoms Aged cheese, soy sauce, and other fermented products

“Chinese Restaurant Syndrome” MSG (monosodium glutamate) is used as a flavor enhancer in soups, stews, and many Chinese food items “Chinese restaurant syndrome” Sensitivity causes dizziness, sweating, flushing, rapid heartbeat, and ringing in the ears

Precautions People with food allergies or intolerances must be very careful about what they eat They should have a plan of action ready in case a serious reaction develops

Take Action to Prevent Anaphylaxis For those at risk of anaphylactic shock: Learn how to avoid foods that trigger reactions Ask your doctor what to do if symptoms appear Fill and carry prescriptions for any needed medications (EpiPens, antihistamines, inhalers) – and learn how to use them Wear an ID bracelet with allergy information