Allergens Presented by Jason M. Behrends, Ph.D., CCS & Frida Bonaparte MSU-ES

What is a food allergy? A food allergy is an immune system response to a food that the body mistakenly believes is harmful. Food allergy is a reaction of the bodys immune system to something in a food or an ingredient in a foodusually a protein. Once the immune system decides that a particular food is harmful, it creates specific antibodies to it. The next time the individual eats that food, the immune system releases massive amounts of chemicals, including histamine, to protect the body. These chemicals trigger a cascade of allergic symptoms that can affect the respiratory system, gastrointestinal tract, skin, and/or cardiovascular system. The immune system's eosinophils, once activated in a histamine reaction, will register any foreign proteins they see. Scientists estimate that approximately 12 million Americans suffer from food allergies.

What is the difference between food allergy and food intolerance? Many people think the terms food allergy and food intolerance mean the same thing; however, they do not. –A food intolerance is an adverse food-induced reaction that does not involve the immune system. Lactose intolerance is one example of a food intolerance. A person with lactose intolerance lacks an enzyme that is needed to digest milk sugar. When the person eats milk products, symptoms such as gas, bloating, and abdominal pain may occur. –A food allergy occurs when the immune system reacts to a certain food. The most common form of an immune system reaction occurs when the body creates immunoglobulin E (IgE) antibodies to the food. When these IgE antibodies react with the food, histamine and other chemicals (called mediators) are released, causing hives, asthma, or other symptoms of an allergic reaction.

What are the major food allergens? Commonly referred to as the big eight Account for 90% of food allergic reactions –Milk –Eggs –Fish –Crustacean shellfish –Tree nuts –Peanuts –Wheat –Soybeans

The mechanism of food intolerance Food intolerance includes any adverse physiological responses that can occur to foods that are not immunologically mediated. It may be due to metabolic, toxic or pharmacological reactions to foods. If foods are contaminated by bacteria or toxins, this can lead to food intolerance in the form of 'food poisoning'. Eating tuna or mackerel that has gone off can lead to scombroid poisoning. Monosodium glutamate can cause flushing, headache and abdominal symptoms. Lactase deficiency, leading to lactose intolerance, is a metabolic non- allergic food intolerance that causes diarrhoea and abdominal symptoms after milk is ingested. Coeliac disease is an autoimmune inflammatory disorder of the small intestine induced by exposure to gluten in genetically predisposed individuals.

The mechanism of food allergy Food allergy occurs when the body's immune system mounts an exaggerated response against the offending food, which acts as an allergen. It is a type of hypersensitivity reaction. It can be either: –A type I, IgE-mediated reaction: this is the usual cause of food allergy. After initial sensitisation, the release of mediators such as histamine are triggered each time a person is exposed to the food. It is these mediators that cause the symptoms. –A delayed, type IV-mediated reaction: these reactions are mediated mainly by T cells. They typically affect the gastrointestinal tract or skin, for example exacerbation of eczema in children after milk ingestion.

Allergic reactions Should contact health care provider for appropriate testing Should read labels and avoid the offending foods Should be taught to recognize the early symptoms, incase of accidental ingestion Should initiate treatment immediately and go to a nearby emergency room if symptoms progress

Allergic reactions Can occur within a few minutes to two hours –Hives –Flushed skin or rash –Tingling or itchy sensation in the mouth –Face, tongue, or lip swelling –Vomiting and/or diarrhea –Abdominal cramps –Coughing or wheezing –Dizziness and or lightheadedness –Swelling of the throat and vocal cords –Difficulty breathing –Loss of consciousness

Severe Food Allergies Can Be Life-Threatening Following ingestion of a food allergen(s) –Can cause a severe, life-threatening allergic reaction called anaphylaxis –Can lead to: Constricted airways in the lungs Severe lowering of blood pressure and shock anaphylactic shock Suffocation by swelling of the throat

Severe Food Allergies Can Be Life-Threatening Each year in the U.S. it is estimated that anaphylaxis to food results in: –30,000 emergency room visits –2,000 hospitalizations –150 deaths Prompt administration of epinephrine by autoinjector (e.g., Epi-pen) during early symptoms of anaphylaxis may help prevent these serious consequences.

Preventing Allergic Reactions Get tested Check ingredients on all food labels Ask restaurant staff how food is prepared and inform them of your allergy People sensitive to a certain food like shellfish or peanuts may have a reaction to other foods if they were prepared in a dish or with utensils that were used to handle the food to which they are allergic Be aware of possible triggers and early warning signs Seek medical care immediately even if you feel better because symptoms can recur in a few hours.

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