Transcript Allergens - Mississippi Extension Service and Experiment

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 body’s immune system to something in
a food or an ingredient in a food—usually 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
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Milk
Eggs
Fish
Crustacean shellfish
Tree nuts
Peanuts
Wheat
Soybeans
The mechanism of food
intolerance
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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 nonallergic 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
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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.
Questions