2. By the end of presentation, participants will be able to:-
Define a food allergy and food intolerance
Describe the types of food allergy and food intolerance
How do allergic reaction work
List the sign and symptoms of food allergy
Identify the “Big 8” food allergen
Describe the diagnosis and management of food allergy
and food intolerance
OBJECTIVE
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3. An Overview of Food Allergies
Definition
Type of food allergy and food intolerance
Mechanism of action
Sign and symptoms
Most common food allergens
Diagnosis
Management
Conclusion
SCOPE
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4. As many as 15 million people have food allergies.
An estimated 9 million, or 4%, of adults have food allergies.
Nearly 6 million or 8% of children have food allergies with
young children affected most.
In 2008, the CDC reported an 18 percent increase in food
allergy among children between 1997 and 2007 (CDC)
According to a study released in 2013 by the Canters for
Disease Control and Prevention, food allergies among
children increased approximately 50% between 1997 and
2011. (Food Allergy Research & Education)
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Overview
5. 5
What is food allergy?
Food allergy is an abnormal response to a food
triggered by the body’s immune system.
Allergic reactions to food can cause serious illness or
even death.
What is food intolerance ?
An abnormal physiological response to eating
Food intolerance is caused by the lack of our body’s
ability to digest certain substances.
Some people may have a food intolerance that has a
psychological trigger.
Food allergy is different with food intolerance
although both can show similar symptoms.
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6. Types of food allergies
12/2/20171-31 6 Source: Adapted from Boyce et al. JACI, 2010
7. IgE mediated food allergy
Reactions occur when allergens bind to
Immunoglobulin E (IgE) antibodies bound to mast cells,
resulting in the release of histamine and other
inflammatory mediators.
Symptoms are usually of rapid onset (<30 minutes in
children, usually <2 hours in adults).
Diagnostic tests (e.g. skin prick and blood tests) are
usually positive.
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8. Non IgE mediated food allergy.
Reactions occur when the ingested food protein causes
an immune response resulting in delayed
normally in the skin or gastrointestinal tract.
Symptoms usually occur 2-24 hours after ingestion of
the food protein.
Diagnostic tests are usually negative. There is no
definitive in vitro test for non IgE mediated food
allergies.
Mixed IgE and non IgE symptom clusters (of the above)
can occur. Non IgE mediated can convert to IgE
mediated allergy and therefore long term follow up is
essential 12/2/20171-31 8
10. How do allergic reactions work?
An immediate allergic reaction involves two actions of our
immune system:
Our immune system produces immunoglobulin E (IgE) – a
type of protein that works against a specific food –
antibody.
IgE attaches basophils (white blood cells) and to mast
cells – cells found in all body tissues. The typical sites of
allergic reactions include nose, throat, lungs, skin and GI
tract.
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11. How do allergic reactions work?
Food allergens are proteins within the food that
enter our bloodstream after the food is digested.
Food allergen go to target organs such as skin,
nose, etc and cause allergic reactions.
An allergic reaction to food can take place within
few minutes to an hour.
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13. How do allergic reactions work?
The symptoms of cell-mediated allergic reactions do not
begin to appear until 6–24 hrs after ingestion of the
offending food. These reactions develop slowly,
reaching a peak at approx. 48 hrs and subsiding after 72–
96 hrs.
The mechanisms of cell-mediated food allergies are not
nearly as well understood.
They involve an interaction between specific food
allergens and sensitized T lymphocytes - a major
component of the gut-associated lymphoid tissue.
Lymphocyte stimulation initiates the release of cytokines
and lymphokines which produces a localized
inflammatory response.
Antibodies are not involved in these reactions.
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14. 14
Examples of Allergic Conditions
and Symptoms
Skin and Mucous Membranes
Atopic dermatitis (eczema)
Urticaria (hives)
Angioedema (swelling of tissues, especially mouth
and face)
Pruritus (itching)
Contact dermatitis (rash in contact with allergen)
Oral symptoms (irritation and swelling of tissues
around and inside the mouth)
Oral allergy syndrome
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15. 15
Examples of Allergic Conditions
and Symptoms
Digestive Tract
Diarrhea
Constipation
Nausea and Vomiting
Abdominal bloating and distension
Abdominal pain
Indigestion (heartburn)
Belching
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16. 16
Examples of Allergic Conditions
and Symptoms
Respiratory Tract
Seasonal or perennial rhinitis (hayfever)
Rhinorrhea (runny nose)
Allergic conjunctivitis (itchy, watery, reddened eyes)
Serous otitis media (earache with effusion)
Asthma
Laryngeal oedema (throat tightening due to
swelling of tissues)
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17. 17
Examples of Allergic Conditions
and Symptoms
Nervous System
Migraine
Other headaches
Spots before the eyes
Restlessness
Hyperactivity
Lack of concentration
Tension-fatigue syndrome
Irritability
Chilliness
Dizziness 12/2/20171-31
18. 18
Anaphylaxis
Severe reaction of rapid onset, involving most organ
systems, which results in circulatory collapse and drop in
blood pressure
In the most extreme cases the reaction progresses to
anaphylactic shock with cardiovascular collapse
This can be fatal
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20. Food Allergy Tests
Diagnosis of allergy is based on a combination of:
Clinical history.
Skin tests
Identifying the type of IgE that is fixed to the skin mast cell.
For example: scratch test.
Blood tests analyze CBC, TFT, GRBS and Urine R/E
RAST (radioallergosorbent test) or ELISA ( enzyme-linked
immunosorbent assay).
These tests measure the presence of
food-specific IgE in blood and
the total IgE level in blood.
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22. 1-31
Management of food allergy
Symptomatic pharmacotherapy
Dietary avoidance
hyposensitization, anti-IgE antibodies, and DNA
vaccination with allergen DNA.
Counseling: nutritional, psychological
HACCP can be adapted to identify and control
potential food allergy problems before they
happen.
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23. 23
Emergency Treatment for
Anaphylactic Reaction
Transport to hospital immediately
Inj adrenaline I/v
Fast-acting antihistamine
corticosteroid
Second phase of reaction is sometimes fatal, especially
in an asthmatic
Patient may appear to be recovering, but 2-4 hours
later symptoms increase in severity and reaction
progresses rapidly
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24. Dietary avoidance
Avoiding to eat foods which can trigger allergic reaction. Strict
avoidance of food allergens and early recognition and
management of allergic reactions to food are important
measures to prevent serious health consequences.
The allergenic capacity of some food allergens is destroyed by
cooking and food processing, when the proteins are denatured.
Newer processing techniques, such as high-pressure treatment
of foods, fermentation and enzyme treatment, can help to
reduce the allergenic and intolerance of some food proteins.
Anti-oxidants prevent damage to body tissues caused by free
radicals which are very reactive small chemicals entities
produced during biochemical reactions in the body tissues.
Vitamin C (or ascorbic acid) is a potent anti-oxidant and can also
act as natural mild anti-histamine.
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25. Consumer Protections & Labeling
Food manufacturers are generally responsible about posting
alerts concerning allergen contamination and recalling their
products.
Labeling of foods containing allergens have to be clear and
consistent.
The application of GMP in food manufacturing to avoid
cross-contamination of food products by foreign allergens.
The awareness of the consumers in checking the labels.
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26. The Codex recommendations
The Codex Alimentarius Commission Committee on Food
Labelling has listed the foods and ingredients that cause the
most severe reactions and most cases of food
hypersensitivity. The following foods and ingredients are
known to cause hypersensitivity and shall always be
declared:
Cereals containing gluten; i.e., wheat, rye, barley, oats, spelt
or their hybridized strains and products of these;
Crustacea and products of these;
Eggs and egg products;
Fish and fish products;
Peanuts, soybeans and products of these;
Milk and milk products (lactose included);
Tree nuts and nut products; and
Sulphite in concentrations of 10 mg/kg or more.”
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27. EU and US regulation
The European Union (EU) directive (EU Directive 2003/89/EC
amending 2013/EC) makes it mandatory for the food
industry to list 12 potential food allergens on the product
labels regardless of the quantity in the finished product.
The United States of America In the United States, the Food
Allergen Labelling and Consumer Protection Act 2004
(FALCPA) of the US Food and Drug Administration (USFDA)
mandates manufacturer disclosure of the most common
allergens (milk, egg, wheat, soy, peanut, tree nuts, fish and
crustacean shellfish) in plain English, using the common or
usual name, in the ingredient list or in a separate allergens
summary statement.
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28. It is important to understand there is currently no cure of food
allergies
staying away from the food that causes food allergies is the
best way to avoid the allergies
The most common food allergens include peanuts, milk, eggs,
tree nuts,fish, shellfish, soy, and wheat — these foods account
for about 90% of all allergic reaction
Food allergy is treated primarily by dietary avoidance
People who have food allergies must identify and prevent
them because, although usually mild and not severe, these
reactions can cause devastating illness and, in rare instances,
can be fatal
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Conclusion
29. ASCIA Health Professional Information Paper (2013).
Nutritional Management of Food Allergy
U.S. Department of Health and Human Services
(2004).Food Allergy: An Overview. Retrieved from
www.niaid.nih.gov.
Janice M. Joneja, Ph.D.(2013) Food Allergies and Food
Intolerances
Rai k.p. class notes ppt
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References
