Do You Have Food Allergies Or Food Intolerances?

Do You Have Food Allergies Or Food Intolerances?
Food allergies or food intolerances affect nearly everyone at some
point. People often have an unpleasant reaction to something they ate
and wonder if they have a food allergy. One out of three people either
say that they have a food allergy or that they modify the family diet
because a family member is suspected of having a food allergy. But only
about three percent of children have clinically proven allergic
reactions to foods. In adults, the prevalence of food allergy drops to
about one percent of the total population.

This difference between the clinically proven prevalence of food
allergy and the public perception of the problem is in part due to
reactions called "food intolerances" rather than food allergies. A food
allergy, or hypersensitivity, is an abnormal response to a food that is
triggered by the immune system. The immune system is not responsible
for the symptoms of a food intolerance, even though these symptoms can
resemble those of a food allergy.

It is extremely important for people who have true food allergies to
identify them and prevent allergic reactions to food because these
reactions can cause devastating illness and, in some cases, be fatal.

An allergic reaction involves two features of the human immune
response. One is the production of immunoglobulin E (IgE), a type of
protein called an antibody that circulates through the blood. The other
is the mast cell, a specific cell that occurs in all body tissues but
is especially common in areas of the body that are typical sites of
allergic reactions, including the nose and throat, lungs, skin, and
gastrointestinal tract.

The ability of a given individual to form IgE against something as
benign as food is an inherited predisposition. Generally, such people
come from families in which allergies are common-not necessarily food
allergies but perhaps hay fever, asthma, or hives. Someone with two
allergic parents is more likely to develop food allergies than someone
with one allergic parent.

Food allergens (the food fragments responsible for an allergic
reaction) are proteins within the food that usually are not broken down
by the heat of cooking or by stomach acids or enzymes that digest food.
As a result, they survive to cross the gastrointestinal lining, enter
the bloodstream, and go to target organs, causing allergic reactions
throughout the body.

The complex process of digestion affects the timing and the location
of a reaction. If people are allergic to a particular food, for
example, they may first experience itching in the mouth as they start
to eat the food. After the food is digested in the stomach, abdominal
symptoms such as vomiting, diarrhea, or pain may start. When the food
allergens enter and travel through the bloodstream, they can cause a
drop in blood pressure. As the allergens reach the skin, they can
induce hives or eczema, or when they reach the lungs, they may cause
asthma. All of this takes place within a few minutes to an hour.

In adults, the most common foods to cause allergic reactions
include: shellfish such as shrimp, crayfish, lobster, and crab;
peanuts, a legume that is one of the chief foods to cause severe
anaphylaxis, a sudden drop in blood pressure that can be fatal if not
treated quickly; tree nuts such as walnuts; fish; and eggs.

In children, the pattern is somewhat different. The most common food
allergens that cause problems in children are eggs, milk, and peanuts.
Adults usually do not lose their allergies, but children can sometimes
outgrow them. Children are more likely to outgrow allergies to milk or
soy than allergies to peanuts, fish, or shrimp.

The foods that adults or children react to are those foods they eat
often. In Japan, for example, rice allergy is more frequent. In
Scandinavia, codfish allergy is more common.

If someone has a life-threatening reaction to a certain food, the
doctor will counsel the patient to avoid similar foods that might
trigger this reaction. For example, if someone has a history of allergy
to shrimp, testing will usually show that the person is not only
allergic to shrimp but also to crab, lobster, and crayfish as well.
This is called cross-reactivity.

Another interesting example of cross-reactivity occurs in people who
are highly sensitive to ragweed. During ragweed pollination season,
these people sometimes find that when they try to eat melons,
particularly cantaloupe, they have itching in their mouth and they
simply cannot eat the melon. Similarly, people who have severe birch
pollen allergy also may react to the peel of apples. This is called the
"oral allergy syndrome."

A differential diagnosis means distinguishing food allergy from food
intolerance or other illnesses. One possibility is the contamination of
foods with microorganisms, such as bacteria, and their products, such
as toxins. Contaminated meat sometimes mimics a food reaction when it
is really a type of food poisoning.

There are also natural substances, such as histamine, that can occur
in foods and stimulate a reaction similar to an allergic reaction. For
example, histamine can reach high levels in cheese, some wines, and in
certain kinds of fish, particularly tuna and mackerel. In fish,
histamine is believed to stem from bacterial contamination,
particularly in fish that hasn't been refrigerated properly. If someone
eats one of these foods with a high level of histamine, that person may
have a reaction that strongly resembles an allergic reaction to food.
This reaction is called histamine toxicity.

Another cause of food intolerance that is often confused with a food allergy is lactase deficiency.
This most common food intolerance affects at least one out of ten
people. Lactase is an enzyme that is in the lining of the gut. This
enzyme degrades lactose, which is in milk. If a person does not have
enough lactase, the body cannot digest the lactose in most milk
products. Instead, the lactose is used by bacteria, gas is formed, and
the person experiences bloating, abdominal pain, and sometimes
diarrhea. There are a couple of diagnostic tests in which the patient
ingests a specific amount of lactose and then the doctor measures the
body's response by analyzing a blood sample.

Another type of food intolerance is an adverse reaction to certain
products that are added to food to enhance taste, provide color, or
protect against the growth of microorganisms. Compounds that are most
frequently tied to adverse reactions that can be confused with food
allergy are yellow dye number 5, monosodium glutamate, and sulfites.
Yellow dye number 5 can cause hives, although rarely. Monosodium glutamate (MSG)
is a flavor enhancer, and, when consumed in large amounts, can cause
flushing, sensations of warmth, headache, facial pressure, chest pain,
or feelings of detachment in some people. These transient reactions
occur rapidly after eating large amounts of food to which MSG has been
added.

Sulfites can occur naturally in foods or are added to enhance
crispness or prevent mold growth. Sulfites in high concentrations
sometimes pose problems for people with severe asthma.
Sulfites can give off a gas called sulfur dioxide, which the asthmatic
inhales while eating the sulfited food. This irritates the lungs and
can send an asthmatic into severe bronchospasm, a constriction of the
lungs. Such reactions led the U.S. Food and Drug Administration (FDA)
to ban sulfites as spray-on preservatives in fresh fruits and
vegetables. But they are still used in some foods and are made
naturally during the fermentation of wine, for example.

Gluten intolerance is associated with the disease called gluten-sensitive enteropathy or Celiac Disease. It is caused by an abnormal immune response to gluten, which is a component of wheat and some other grains.

Some people may have a food intolerance that has a psychological
trigger. In selected cases, a careful psychiatric evaluation may
identify an unpleasant event in that person's life, often during
childhood, tied to eating a particular food. The eating of that food
years later, even as an adult, is associated with a rush of unpleasant
sensations that can resemble an allergic reaction to food.

To diagnose food allergy a doctor must first determine if the
patient is having an adverse reaction to specific foods. This
assessment is made with the help of a detailed patient history, the
patient's diet diary, or an elimination diet.

If the patient's history, diet diary, or elimination diet suggests a
specific food allergy is likely, the doctor will then use tests that
can more objectively measure an allergic response to food. One of these
is a scratch skin test, during which a dilute extract of the food is
placed on the skin of the forearm or back. This portion of the skin is
then scratched with a needle and observed for swelling or redness that
would indicate a local allergic reaction. If the scratch test is
positive, the patient has IgE on the skin's mast cells that is specific
to the food being tested.

Skin tests are rapid, simple, and relatively safe. But a patient can
have a positive skin test to a food allergen without experiencing
allergic reactions to that food. A doctor diagnoses a food allergy only
when a patient has a positive skin test to a specific allergen and the
history of these reactions suggests an allergy to the same food.

The final method used to objectively diagnose food allergy is
double-blind food challenge. This testing has come to be the "gold
standard" of allergy testing. Various foods, some of which are
suspected of inducing an allergic reaction, are each placed in
individual opaque capsules. The patient is asked to swallow a capsule
and is then watched to see if a reaction occurs. This process is
repeated until all the capsules have been swallowed. In a true
double-blind test, the doctor is also "blinded" (the capsules having
been made up by some other medical person) so that neither the patient
nor the doctor knows which capsule contains the allergen.

The advantage of such a challenge is that if the patient has a
reaction only to suspected foods and not to other foods tested, it
confirms the diagnosis. Someone with a history of severe reactions,
however, cannot be tested this way. In addition, this testing is
expensive because it takes a lot of time to perform and multiple food
allergies are difficult to evaluate with this procedure.

Food allergy is treated by dietary avoidance. Once a patient and the
patient's doctor have identified the food to which the patient is
sensitive, the food must be removed from the patient's diet. To do
this, patients must read lengthy, detailed ingredient lists on each
food they are considering eating. Many allergy-producing foods such as
peanuts, eggs, and milk, appear in foods one normally would not
associate them with. Peanuts, for example, are often used as a protein
source and eggs are used in some salad dressings. The FDA requires
ingredients in a food to appear on its label. People can avoid most of
the things to which they are sensitive if they read food labels
carefully and avoid restaurant-prepared foods that might have
ingredients to which they are allergic.

In highly allergic people even minuscule amounts of a food allergen
(for example, 1/44,000 of a peanut kernel) can prompt an allergic
reaction. Other less sensitive people may be able to tolerate small
amounts of a food to which they are allergic.

There are several medications that a patient can take to relieve
food allergy symptoms that are not part of an anaphylactic reaction.
These include antihistamines to relieve gastrointestinal symptoms,
hives, or sneezing and a runny nose. Bronchodilators can relieve asthma
symptoms. These medications are taken after people have inadvertently
ingested a food to which they are allergic but are not effective in
preventing an allergic reaction when taken prior to eating the food. No
medication in any form can be taken before eating a certain food that
will reliably prevent an allergic reaction to that food.

There are several disorders thought by some to be caused by food
allergies, but the evidence is currently insufficient or contrary to
such claims. It is controversial, for example, whether migraine
headaches can be caused by food allergies. There are studies showing
that people who are prone to migraines can have their headaches brought
on by histamines and other substances in foods. The more difficult
issue is whether food allergies actually cause migraines in such
people. There is virtually no evidence that most rheumatoid arthritis or osteoarthritis

can be made worse by foods, despite claims to the contrary. There is
also no evidence that food allergies can cause a disorder called the
allergic tension fatigue syndrome, in which people are tired, nervous,
and may have problems concentrating, or have headaches.

Cerebral allergy is a term that has been applied to people who have
trouble concentrating and have headaches as well as other complaints.
This is sometimes attributed to mast cells degranulating in the brain
but no other place in the body. There is no evidence that such a
scenario can happen, and most doctors do not currently recognize
cerebral allergy as a disorder.

Another controversial topic is environmental illness. In a seemingly
pristine environment, some people have many non-specific complaints
such as problems concentrating or depression. Sometimes this is
attributed to small amounts of allergens or toxins in the environment.
There is no evidence that such problems are due to food allergies.

Some people believe hyperactivity in
children is caused by food allergies. But researchers have found that
this behavioral disorder in children is only occasionally associated
with food additives, and then only when such additives are consumed in
large amounts. There is no evidence that a true food allergy can affect
a child's activity except for the proviso that if a child itches and
sneezes and wheezes a lot, the child may be miserable and therefore
more difficult to guide. Also, children who are on anti-allergy
medicines that can cause drowsiness may get sleepy in school or at home.

Controversial treatments include putting a dilute solution of a
particular food under the tongue about a half hour before the patient
eats that food. This is an attempt to "neutralize" the subsequent
exposure to the food that the patient believes is harmful. As the
results of a carefully conducted clinical study show, this procedure is
not effective in preventing an allergic reaction.

Here is a delicious vegan cake that is Milk-free; Egg-free;
Wheat-free; Peanut-free; Soy-free; and Nut-free! Top with
confectioners' sugar poured over a doily to dress it up for dinner or a
party.

Snacking Cake (© 2000 Food Allergy Network)

1 1/2 cups flour
1 tsp. baking soda
1 tsp. cinnamon
1/2 tsp. nutmeg
1/2 tsp. salt
3 T. oil, 3 T. water, and 2 tsp. baking powder, mixed together
1/2 cup oil
1/2 cup brown sugar

1/2 cup white sugar
1 1/2 cups finely grated carrots (about 4 large)
one 8-ounce can of crushed pineapple, packed in its own juice, undrained

Preheat oven to 350 degrees. Grease a 9-inch square or 7-by-11-inch pan.
In a large bowl, mix together flour, baking soda, cinnamon, nutmeg, and salt. Set aside.
In another bowl, combine oil, water, and baking powder mixture
with the oil. Add brown and white sugars, stir well. Set aside.
In a third bowl, combine the carrots and pineapple with its juice. Set aside.
Stir the oil, water, and baking powder mixture into the dry ingredients.
Stir in the carrot-pineapple mixture. Spoon batter into the prepared
pan. Bake 30 to 40 minutes or until a cake tester inserted at the
center comes out dry.