Title: Food Allergies
1Food Allergies
2Outlines
- Statistics
- What is food allergy?
- Immunology concepts
- What foods causes allergies?
- Possible ways to deal with food allergy
- Resources for food allergies
3How 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.
CEN/January 7, 2002 page 21.
4What 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.
- Some foods may contain haptens or haptens
carrier. (A hepten- a small molecule that has the
ability to combine with an antibody (Ab) or a
cell-surface receptor e.g. poison ivy)
5(No Transcript)
6Understanding 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.)
7Terminology
- 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! - Haptens - a small molecule that has the ability
to combine with an Ab or a cell-surface receptor.
8Types of food allergies
- Immediate hypersensitivity with IgE which 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 (gt8hours after
ingestion) cellular immunity involving
T-lymphocytes and macrophages
9Understanding 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) - Cellular defenses (certain cells can eat
invaders-phagocytes) - Inflammation (reddening, swelling and temperature
increase of the affected sites) - Fever (elevated body temperature)
- Molecular defenses (interferons or complementary
system etc.) - Specific defenses or specific immunity
- Antibodies (many kinds of antibodies for many
kinds of antigens)
10Stages of food allergyor hypersensitivity
- A. Sensitization initial meeting of an allergen
and the immune system that results in IgE
production! - B. Activation of mast cells
- IgE
- Non-IgE substances (eg. Drugs)
11Understanding 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.
12Specific Immunity
Immunity
An Antibodies
Acquired
Innate (inborn) Genetic factors
Passive (Ready-made-An)
Active (own An)
Natural Maternal An
Artificial (An from Other sources)
Natural (Exposure to Foreign Agents)
Artificial (immunization)
13What are Acquired-Active-Natural Specific
Antibodies (Immunoglobulins)
- There are five classes of Immunoglobulins
- 1) IgG Main class of antibodies in blood-also
from mother-to-child (20) - 2) IgA Small amount in blood, but larger amount
in tears, milk, saliva, mucus and the lining
tissues - 3) IgM First Antibody secreted during the
primary response - 4) IgE (Reagin) Found mainly in body fluids
and skin --- Associated with allergy reactions! - 5) IgD Found in B-Cell membrane
14(No Transcript)
15Nature of IgE Allergic Reactions
Antigen IgE Mast cells Mediator
release Mediators histamine and others
Picture credit used with permission from Dr.
Gary E. Kaiser http//www.cat.cc.md.us/courses/bio
141/lecguide/index.html
16Who makes the immunoglobulin IgE?
The allergen enters the body and is recognized by
sIg on a B-lymphocyte. The B-lymphocyte
proliferates and differentiates into plasma cells
that produce and secrete IgE against the allergen.
Picture credit used with permission from Dr.
Gary E. Kaiser http//www.cat.cc.md.us/courses/bio
141/lecguide/index.html
17Whats next?
The next time the allergen enters the body, it
cross-links the Fab portions of the IgE bound to
the mast cell. This triggers the mast cell to
degranulate, that is, release its histamine and
other inflammatory mediators.
- Picture credit used with permission from Dr.
Gary E. Kaiser - http//www.cat.cc.md.us/courses/bio141/lecguide/in
dex.html
18Nature of IgE Allergic Reactions
Antigen IgE Mast cells Mediator
release Mediators histamine and others
Picture credit used with permission from Dr.
Gary E. Kaiser http//www.cat.cc.md.us/courses/bio
141/lecguide/index.html
19What does histamine do?
- Vasodilation
- Increased capillary permeability
- Bronchoconstriction
20Primary and secondary responses to an antigen
Primary response first response when hosts
B-cell recognize the antigen
Secondary response upon second exposure to the
antigen, the Memory cells will divide, thus make
more of the total antibody
21(No Transcript)
22Symptoms-Food Allergy
- Nausea
- Diarrhea
- Abdominal cramps
- Pruritic rashes
- Angioedema
- Asthma/rhinitis
- Vomiting
- Hives
- Laryngeal edema
- Anaphylaxis
Exercise exacerbates symptoms
23What 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
24Itsnot easyliving with food allergies!
What would you choose to eat, if you are
allergic to milk or dairy products?
25Hidden 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
26What about food Additives?
- Sulfur-based preservatives
- Sulfites
- Aspartame (a sweetener)- PKU
- Monosodium glutamate
- FDC Yelow 5 (Tartrazine)
27Cross-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!
28To make the matter worse!
- Eating out is a nightmare?
- African, Chinese, Indonesian, Mexican, Thai, and
Vietnamese dishes often contain peanuts. It is
recommended that peanut-allergic individuals
avoid these types of foods and restaurants. - For traditional food restaurants,
cross-contamination of allergens to other foods
can also a problem.
29How to deal with food allergy!
- There is no specific antibody for any specific
foods available! - People who have food allergy need a total
avoidance of the offending foods. - Read food ingredient list.
- Eliminate cross-contamination during cooking and
preparation!!!!
30Common 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) - sodium cromolyn (prevents mast cells from
releasing histamines).
31Other types of food allergy, Non-IgE Mediated
- Immune Complex-mediated
- Symptoms usually gastrointestinal
- Delayed type hypersensitivity
- Symptoms usually gastrointestinal
32How 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)
33What about Allergy VS Intolerance!
- True Allergy-Total avoidance necessary!
- Intolerance- Small amount may be tolerated
34Other causes of allergy-like food problems
- Microbial products- e.g. histamine Some food
products have high levels of histamine (eg
fermented foods) - Pharmacological reaction-tyramine,
phenylethylamine, caffeine dose dependent - Idiosyncratic reactions (adverse reactions of
drugs etc dose dependent) - Psychological disorders
35Food allergy and biotechnology
- Although it is not easy to predict potential
allergenicity of foods derived from GMO!, there
are some criteria to go by - Sources of transferred genetic material While
the crops from which staple foods are derived
contain tens of thousands of different proteins,
relatively few are allergenic. - Synthesis of allergenic proteins also depends on
the growing conditions and other stress factors. - Molecular weight of most known allergens are
between 10,000 and 40,000.
36Food allergies and biotechnology
- The amino acid sequence of many allergens is
readily available. - Labile allergens in foods that are eaten cooked
or undergo other processing before consumption
are of less concern. - Most allergens are resistant to gastric acidity
and to digestive proteases. - New proteins expressed in non-edible portions of
plants, for example are not of a concern in terms
of food allergy.
37Resources for food allergies
- Food Allergy and Anaphylaxis network (FAAN)
- Other resources
- See handouts
38Questions?