Food Allergies - PowerPoint PPT Presentation

1 / 38
About This Presentation
Title:

Food Allergies

Description:

Experts agree that allergies in developed countries are becoming ... African, Chinese, Indonesian, Mexican, Thai, and Vietnamese dishes often contain peanuts. ... – PowerPoint PPT presentation

Number of Views:217
Avg rating:3.0/5.0
Slides: 39
Provided by: umani
Category:
Tags: allergies | food

less

Transcript and Presenter's Notes

Title: Food Allergies


1
Food Allergies
2
Outlines
  • Statistics
  • What is food allergy?
  • Immunology concepts
  • What foods causes allergies?
  • Possible ways to deal with food allergy
  • Resources for food allergies

3
How 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.
4
What 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)
6
Understanding 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.)

7
Terminology
  • 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.

8
Types 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

9
Understanding 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)

10
Stages 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)

11
Understanding 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.

12
Specific 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)
13
What 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)
15
Nature 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
16
Who 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
17
Whats 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

18
Nature 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
19
What does histamine do?
  • Vasodilation
  • Increased capillary permeability
  • Bronchoconstriction

20
Primary 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)
22
Symptoms-Food Allergy
  • Nausea
  • Diarrhea
  • Abdominal cramps
  • Pruritic rashes
  • Angioedema
  • Asthma/rhinitis
  • Vomiting
  • Hives
  • Laryngeal edema
  • Anaphylaxis

Exercise exacerbates symptoms
23
What 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

24
Itsnot easyliving with food allergies!
What would you choose to eat, if you are
allergic to milk or dairy products?
25
Hidden 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

26
What about food Additives?
  • Sulfur-based preservatives
  • Sulfites
  • Aspartame (a sweetener)- PKU
  • Monosodium glutamate
  • FDC Yelow 5 (Tartrazine)

27
Cross-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!

28
To 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.

29
How 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!!!!

30
Common 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).

31
Other types of food allergy, Non-IgE Mediated
  • Immune Complex-mediated
  • Symptoms usually gastrointestinal
  • Delayed type hypersensitivity
  • Symptoms usually gastrointestinal

32
How 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)

33
What about Allergy VS Intolerance!
  • True Allergy-Total avoidance necessary!
  • Intolerance- Small amount may be tolerated

34
Other 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

35
Food 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.

36
Food 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.

37
Resources for food allergies
  • Food Allergy and Anaphylaxis network (FAAN)
  • Other resources
  • See handouts

38
Questions?
Write a Comment
User Comments (0)
About PowerShow.com