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Allergies: Food
What is an allergy?
Allergy is defined as an abnormal reaction to certain substances
called allergens. These allergens may be inhaled, swallowed,
or come in contact with the skin to cause a reaction from
the body's immune system.
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What is a food allergy?
A food allergy is an adverse reaction or a negative response
to a food or a food additive that is eaten. Both raw and cooked
foods can cause allergic reactions. Allergic reactions to
foods can occur within seconds to a few hours of eating the
specific food. When a true food allergy occurs, a person's
immune system will react to food that would normally be harmless.
The body's immune system reacts to food proteins called allergens
and tries to protect the person's body from this 'harmful'
food by producing increasing amounts of antibodies. The antibody,
called IgE (pronounced "im-mu-no-glob-u-lin"), causes
an allergic reaction. People with allergies have IgE circulating
in their blood. Antibodies cause the person's blood vessels
to enlarge, smooth muscles to contract and affected skin areas
to become red, itchy and swollen.
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Common food offenders
Food allergy patterns in adults vary somewhat from those
in children. For adults, the most common food allergies are:
shrimp, lobster, crab, and other shellfish; peanuts (one of
the chief foods responsible for severe anaphylaxis); walnuts
and other tree nuts; fish; and eggs.
In children, eggs, milk, peanuts, soy and wheat are the main
offenders. Children typically outgrow their allergies to milk,
egg, soy and wheat, while allergies to peanuts, tree nuts,
fish, and shrimp usually are not outgrown. Adults usually
do not lose their allergies.
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What is a food allergen?
Food allergens (the food fragments responsible for an allergic
reaction) are proteins within the food.
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What are the symptoms of a food allergy?
Skin reactions to foods
One common food allergy is atopic
dermatitis, also known as eczema. This skin condition
affects forty percent of people with food allergies. For people
with this condition, the reaction is made worse by foods that
they eat.
What is atopic dermatitis?
Dermatitis means inflammation of the skin. Atopic dermatitis
is another name for eczema. With this condition, the skin
becomes extremely itchy and swollen, causing redness,
cracking, weeping, crusting and scaling in the skin folds
under the armpit and behind the knees. Eczema often occurs
together with asthma and hay fever.
Another common allergic skin reaction to a food is hives.
Hives are red, very itchy, swollen areas of the skin that
may arise suddenly and leave quickly. They often appear in
clusters, with new clusters appearing as other areas clear.
Hives may occur alone or with other symptoms.
Other reactions to foods
Signs or symptoms of an allergic reaction can range from
tingling sensation in the mouth; swelling of the tongue, lips
and throat; wheezing; difficulty (problems) breathing; hives;
vomiting; abdominal cramps; diarrhea; low blood pressure;
and rarely, a severe allergic reaction can cause anaphylaxis
which can be life threatening. Foods most likely to cause
anaphylaxis are peanuts, tree nuts and shellfish.
What is anaphylaxis?
Anaphylaxis is a sudden, severe, potentially life threatening,
widespread allergic reaction that can involve many areas
of the body (such as the skin, respiratory tract, digestive
tract, and cardiovascular system). Symptoms occur within
minutes to two hours after contact with the allergy-causing
substance, but in rare instances may occur up to four hours
later. Anaphylactic reactions can be mild to life threatening
and can include: hives; swelling of lips, throat, tongue
or around the eyes; difficulty swallowing or breathing;
redness of skin; increased heart rate; decreased blood pressure;
weakness; anxiety; collapse; and loss of consciousness (citations
from AAN/A and from www.foodallergy.org).
If you have ever had an anaphylactic reaction (as described
above), you need to know the early symptoms, such as numbness
of tongue and lips. You should discuss precautions and future
plans with your medical provider.
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What is the difference between
'food intolerance' and 'food allergy'?
Food intolerance is when a person has an abnormal physical
response to a food or food additive that is not an allergic
reaction. The difference is that food intolerance does not
affect the immune system. For example, lactose intolerance
is when the person does not have the enzyme that is needed
to absorb milk sugar. When the person eats milk products,
they may have symptoms of gas, bloating, and abdominal pain.
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Why do I have a food allergy?
Heredity is the main reason some people have allergies and
others do not. People usually inherit the ability to form
Immunglobulin E (IgE) against food. Those more likely to develop
food allergies come from families in which allergies such
as hay fever, asthma, or eczema are common.
How to avoid food allergies?
- It is best to avoid food that causes your symptoms.
If your child is allergic to milk, he or she should avoid
the following foods and ingredients:
- Artifical butter flavor, butter fat, butter oil, buttermilk
- Cheese, cream cottage cheese, curds, whey
- Custard, pudding, yogurt
- Ghee (clarified butter)
- Half and Half
- Casein, caseinates, rennet casein
- Lactalbumin, lactalbumin phosphate, lactoglobulin,
lactulose
- All forms of milk: condensed, dry evaporated, milk
from goats or other animals, low-fat, malted, milkfat,
nonfat, powdered, protein, skimmed, solid and whole
- Children who are allergic to eggs should avoid the following
foods and ingredients:
- Egg
- Eggnog
- Albumin
- Lysozyme
- Mayonnaise
- Meringue or meringue power
- Surimi
- These items also may include egg protein: flavoring,
lecithin, macaroni, marzipan, marshmallows, nougat,
and pasta
- Children who are allergic to peanuts should avoid the
following foods and ingredients:
- Artificial nuts, beer nuts, ground nuts, mixed nuts
- Cold pressed, expelled or extruded peanut oil and
arachis oil
- Goobers, Nu-Nuts flavored nuts
- Mandelonas
- Peanuts, peanut butter, peanut flour
- These items may include peanut protein: African, Chinese,
Indonesian, Mexican, Thai and Vietnamese dishes, baked
goods, candy, chilie, egg rolls, enchilada sauce, flavoring,
marzipan, nougat and sunflower seeds
- Teach children with food allergies not to accept food
from classmates or friends. Make sure parents and teachers
are aware of your child's allergy.
- Teach students and teachers to recognize the symptoms
of allergic reaction, particularly symptoms of anaphylaxis.
- Read the labels from manufacturers of any food products
you purchase at the grocery store and ask questions at restaurants.
The Food and Drug Administration (FDA) has developed a policy
for food manufacturers that requires a complete listing
of all food ingredients, specifically allergenic ingredients.
- If you eat out, always ask restaurant staff about ingredients
in the food and how the food is prepared. Cooking oils can
contain allergens, particularly peanut oils.
- Recognize those who are most at risk of developing a food
allergy by asking your family if anyone has a history of
food allergies.
- Tell your friends or anyone serving you food that you
have food allergies.
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What is FDA's policy on allergens?
Products that contain an allergenic ingredient by design
must comply with section 403(i)(2) of the Federal Food, Drug,
and Cosmetic Act (the Act), which requires each ingredient
in a food to be declared. Processing aids that contain allergenic
ingredients must be declared in accordance with 21 CFR 101.4(a)(1).
Production practices that lead to unintentional addition of
allergens to food may be considered unsanitary conditions
that may render the food injurious to health and cause the
food product to be adulterated under section 402(a)(4) of
the Act.
The only exemption to labeling requirements is found in section
403(i)(2) of the Act and provides that spices, flavors, and
certain colors used in food may be declared collectively without
naming each. In some instances, these ingredients contain
sub-components that are allergens. Therefore, FDA strongly
encourages the declaration of any allergenic ingredient contained
in a spice, flavor, or color. The Agency is considering whether
to require, by regulation, declaration of an allergenic ingredient
in a spice, flavor, or color, 403(i) notwithstanding.
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How are food allergies diagnosed?
There are several steps in finding out if you have a food
allergy. Your medical provider would need to take a detailed
history and physical exam. There are several tests, some of
which use extracts of suspected foods. Your medical provider
will decide which tests will be used first.
a. Skin test - involves scratching or pricking your skin
usually in the forearm or back allowing a tiny amount of
one or more extracts to enter the skin.
b. RAST (radioallergsorbent test) is a blood test that
tests for the antibody of a specific food. The results usually
take a week.
c. Oral food challenge - this test may be necessary if
the results of other tests still are unclear. It requires
taking foods that are suspected of causing allergic results.
This test needs to be done with a specialized medical provider
available.
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