Food Allergies
When Eating Is Risky
by Audrey T. Hingley

Do you start itching whenever you eat peanuts? Does seafood
cause your stomach to churn? Symptoms like these cause millions
of Americans to suspect they have a food allergy.
But true food allergies affect a relatively small percentage of
people: Experts estimate that only 2 percent of adults, and from 2
to 8 percent of children, are truly allergic to certain foods. Food
allergy is different from food intolerance, and the term is
sometimes used in a vague, all-encompassing way, muddying the
waters for people who want to understand what a real food allergy
is.
"Many people who have a complaint, an illness, or some
discomfort attribute it to something they have eaten. Because in
this country we eat almost all the time, people tend to draw false
associations [between food and illness]," says Dean Metcalfe,
M.D., head of the Mast Cell and Physiology Section at the
National Institute of Allergy and Infectious Diseases.
For example, food intolerance may produce symptoms similar to
food allergies, such as abdominal cramping. But while people with
true food allergies must avoid offending foods altogether, people
with food intolerance can often eat small amounts of the offending
food without experiencing symptoms.
Lactose intolerance, for instance, is sometimes mistaken for milk
allergy. Lactose intolerance is a problem of digestion due to an
enzyme deficiency, with cramps and diarrhea the common
hallmarks. Estimates are that about 80 percent of African-
Americans have lactose intolerance, as do many people of
Mediterranean or Hispanic origin. It is quite different from the
true allergic reaction some have to the proteins in milk. Unlike
allergies, intolerances generally intensify with age.

Dangerous Dishes
For people with true food allergies, the simple pleasure of eating
can turn into an uncomfortable--and sometimes even dangerous--
situation. For some, food allergies cause only hives or an upset
stomach; for others, one bite of the wrong food can lead to serious
illness or even death.
FDA regulates drugs used to treat severe allergic reactions and has
recently issued regulations under the Nutrition Labeling and
Education Act of 1990 to make such reactions less likely.
The early Greek philosopher and physician Hippocrates was one
of the first to note that cow's milk caused health problems for
some people, but it was not until the early 1900s in Europe that
the first scientifically documented food allergy reports began to
appear. The word "allergy" is derived from a Greek word meaning
"altered reaction," and initially conveyed the idea that certain
substances could cause adverse reactions in some people while
having no effect on the public at large.
By the mid-1920s, allergists had defined food allergy as an
abnormal response of the immune system to an otherwise harmless
food. Food allergens, those parts of food causing allergic
reactions, are usually proteins. When the allergen passes from the
mouth into the stomach, the body recognizes it as a foreign
substance, producing antibodies to halt the invasion. In allergic
individuals, as the body  fights off the invasion, symptoms begin
to appear throughout the body. The most common sites are the
mouth (swelling of the lips or tongue, itching lips), digestive tract
(stomach cramps, vomiting, diarrhea), the skin (hives, rashes or
eczema), and the airways (wheezing or breathing problems).
Food allergies are much more common in infants and young
children, who often later outgrow them. Increased susceptibility of
young infants to food allergic reactions is believed to be the result
of immunologic immaturity and, to some extent, intestinal
immaturity. Older children and adults may lose their sensitivity to
certain foods if the responsible food allergen can be identified and
completely eliminated from the diet, although some food allergies
can last a lifetime.
Heredity may cause a predisposition to have allergies of any type.
Some experts believe that, rarely, a specific allergy can be passed
on from parent to child. Several studies have indicated that
exclusive breast-feeding, especially with maternal avoidance of
major food allergens, may deter some food allergies in infants and
young children. (Smoking during pregnancy can also result in the
increased possibility that the baby will have allergies.) Most
patients who have true food allergies have other types of allergies,
such as dust or pollen, and children with both food allergies and
asthma are at increased risk for more severe reactions.
Repeated exposure to allergens starts sensitizing those who are
susceptible. Cow's milk, eggs, wheat, and soy are the most
common food allergies in children. An early peanut allergy may
be lifelong. Adults are usually most affected by nuts, fish,
shellfish, and peanuts.

Life-Threatening Reactions
The greatest danger in food allergy comes from anaphylaxis, a
violent allergic reaction involving a number of parts of the body
simultaneously. Like less serious allergic reactions, anaphylaxis
usually occurs after a person is exposed to an allergen to which he
or she was sensitized by previous exposure (that is, it does not
usually occur the first time a person eats a particular food).
Although any food can trigger anaphylaxis (also known as
anaphylactic shock), peanuts, tree nuts, shellfish, milk, eggs, and
fish are the most common culprits. As little as one-fifth to one-
five-thousandth of a teaspoon of the offending food has caused
death.
Anaphylaxis can produce severe symptoms in as little as 5 to 15
minutes, although life-threatening reactions may progress over
hours. Signs of such a reaction include: difficulty breathing,
feeling of impending doom, swelling of the mouth and throat, drop
in blood pressure, and loss of consciousness. The sooner
anaphylaxis is treated, the greater the person's chance of
surviving. The person should be taken to a hospital emergency
room, even if symptoms seem to subside on their own.
There is no specific test to predict the likelihood of anaphylaxis,
although allergy testing may help determine what a person may be
allergic to and provide some guidance as to the severity of the
allergy. Experts advise people who are susceptible to anaphylaxis
to carry medication, such as injectable epinephrine, with them at
all times, and to check the medicine's expiration date regularly.
Doctors can instruct patients with allergies on how to  self-
administer epinephrine. Such prompt treatment can be crucial to
survival.
Injectable epinephrine is a synthetic version of a naturally
occurring hormone also known as adrenaline. For treatment of an
anaphylactic reaction, it is injected directly into a thigh muscle or
vein. It works directly on the cardiovascular and respiratory
systems, causing rapid constriction of blood vessels, reversing
throat swelling, relaxing lung muscles to improve breathing, and
stimulating the heartbeat.
Epinephrine designed for emergency home use comes in two
forms: a traditional needle and syringe kit known as Ana-Kit, or
an automatic injector system known as Epi-Pen. Epi-Pen's
automatic injector design, originally developed for use by military
personnel to deliver antidotes for nerve gas, is described by some
as "a fat pen." The patient removes the safety cap and pushes the
automatic injector tip against the outer thigh until the unit
activates. The patient holds the "pen" in place for several seconds,
then throws it away.
While Epi-Pen delivers one premeasured dosage, the Ana-Kit
provides two doses. Which system a patient uses is a decision to
be made by the doctor and patient, taking into account the doctor's
assessment of the patient's individual needs.

Advice from Study
Hugh A. Sampson, M.D., and colleagues at Johns Hopkins
University School of Medicine in Baltimore, Md., published a
study of anaphylactic reactions in children in the Aug. 6, 1992,
issue of The New England Journal of Medicine. The study
involved 13 children who had severe allergic reactions to food: Six
died, and seven nearly died. Among the study's conclusions:
  Asthma, a disease with allergic underpinnings, was common to
all children in the study.
  Epinephrine should be prescribed and kept available for those
with severe food allergies.
  Children who have an allergic reaction should be observed for
three to four hours after a reaction in a medical center capable of
dealing with anaphylaxis.
Anne Munoz-Furlong, who founded The Food Allergy Network
for people with food allergies in 1991 after struggling to deal with
her own child's allergies, comments: "My youngest daughter was
diagnosed with milk and egg allergies when she was 9 months old,
nine years ago. We tried to lead a life around her restricted diet.
For example, we had Jell-O mold for her first birthday because I
didn't know it was possible to create a cake without milk or eggs.
I knew there must be other families struggling with the same
issues."

Finding the Forbidden
Because there is no "cure" for food allergies other than strict
avoidance of an offending food, one of the biggest problems those
with food allergies face is verifying whether a forbidden product
is contained in a particular food. For example, in Sampson's
study, all six deaths occurred because either the child or the parent
was unaware the food contained a substance to which the child was
allergic. Munoz-Furlong says the Nutrition Labeling and Education
Act, which requires more complete food labeling, should greatly
help people with food allergies to avoid dangerous foods.
 "The new labeling changes will make it easier for the consumer
to readily identify things they could be allergic to," says Linda
Tollefson, D.V.M., chief of the epidemiology branch at FDA's
Center for Food Safety and Applied Nutrition. "Before this law
was passed, true allergens were required to be on the label, but the
exceptions were standardized foods, which will now have to list all
ingredients."
According to Elizabeth J. Campbell, director of the center s
division of programs and enforcement policy, the principle
underlying standardized foods originally was that people basically
knew what was in various foods.
"Originally food standards were adopted to ensure uniformity. If
you saw a product labeled mayonnaise, food standardization meant
it had to be mayonnaise. People used to know what was in
mayonnaise; nowadays they have to be told that mayonnaise
contains both eggs and oil," Campbell says. "Years ago when the
law was first written to provide for standards of identity for certain
foods, it only required that optional ingredients be declared. The
new law stipulates that all ingredients in standardized foods must
be declared." (See "Ingredient Labeling: What's in a Food?" in the
April 1993 FDA Consumer.)
Campbell believes that once the labeling is in place, consumers
will have the information they need to make correct food choices.
"In most cases, ingredients have to be labeled simply because they
are ingredients, not because they are unsafe," she stresses. "For
those with food allergies, I think it is more of a patient education
problem."
Food additives, such as sulfites and certain colors, can also cause
problems for people sensitive to them. (See "A Fresh Look at
Food Preservatives" in the October 1993 FDA Consumer and
"From Shampoo to Cereal: Seeing to the Safety of Color
Additives  on page 14 of this issue.)
"If you have a food allergy, you really have to alter your life,"
Tollefson says. "You have to really read labels, and really be
careful about what you eat."
Steve Taylor, Ph.D., a professor and head of the Department of
Food Science and Technology at the University of Nebraska in
Lincoln, says the biggest problem for people with food allergies is
restaurant food. Historically, restaurants have been regulated by
local health departments and have not had to label foods.
"For many restaurants, labeling of food products they serve would
cause horrendous problems ... what about chalkboard menus? How
would you include all the ingredients? Enforcement would be a
nightmare," he admits.
But steps are being taken to better educate restaurant employees.
The Food Allergy Network and The American Academy of
Allergy and Immunology, along with The National Restaurant
Association, recently produced a pamphlet on food allergies, which
has been distributed to 30,000 members of the association. The
brochure explains what restaurants can do to help customers who
need to avoid certain foods, defines anaphylaxis, and advises
employees on what to do if food allergy incidents occur.
John A. Anderson, M.D., director of the Allergy and Immunology
Training Program at Henry Ford Hospital in Detroit, says changes
in food habits may be responsible for the feeling some physicians
have that food allergies may be on the rise.
 "You could make a case for the fact that we are introducing
peanuts, in the form of peanut butter, to people at a very young
age, which would affect the prevalence rate for people who are
sensitive to that allergen," he notes. "In Japan, where they use
more soy, there is a higher prevalence of soy allergy. My feeling
is that as soy, a cheap protein supplement, is put in a lot of
commercial foods you will see an increase in the rate of sensitivity
worldwide."
Metcalfe says that if food allergies are rising, it is due to more
common use of foods that tend to be allergenic. He cites milk as
a source of protein supplement in many prepared foods, and points
out that people are eating more exotic seafood and more fish.
"But it's important to remember that the majority of people with
true food allergies are allergic to three or fewer foods," Metcalfe
says.
Other than advising anyone with a known or suspected severe food
allergy to carry and know how to self-administer epinephrine,
there is no treatment for food allergy other than to eliminate the
offending food. But Metcalfe is optimistic about the future.
"I don't think it is likely a drug will be found to prevent food
allergies. But I do think within 10 years we will see allergy shots
available for some of the more common food allergies, because we
are learning to identify and purify food allergens. I think we will
see some development of immunotherapy for food allergies," he
says. n

Audrey T. Hingley is a writer in Mechanicsville, Va.
How to Cope
What do you do if you suspect you have a food allergy?
The Food Allergy Network's Anne Munoz-Furlong suggests
keeping a food diary as a first step, writing down everything you
eat or drink for a one- or two-week period. Note any symptoms
and how long it took for such symptoms to develop.
But Furlong and other experts agree that those who suspect food
allergies also need to be evaluated by a physician with intensive
specialty training in allergy and immunology. Be sure to discuss
what diagnostic and treatment plan is anticipated, and the costs.
Ask if the tests have been proven effective by accepted standards
of scientific evaluation.
"Go to a board-certified physician who is an allergy expert,"
advises Paul C. Turkeltaub, M.D., associate director of the
division of allergenic products and parasitology at FDA's Center
for Biologics Evaluation and Research. "Be very wary of claims
of food allergy to explain chronic, common complaints."
The diagnosis of food allergy requires a careful history, physical
exam, appropriate exclusion diet, and diagnostic tests to rule out
other conditions. Tests can include direct allergy skin tests, blood
tests, or "elimination and challenge" tests for suspected foods.
The most accurate kind of test is a controlled challenge test, often
done in "blind" or "double-blind" fashion to eliminate
psychological factors. In a blind challenge, the patient is given
either a sample of the food, without being told what it is, or a
placebo, an inert substance used as a control in the test. The
observer (a doctor or assistant), however, knows what the
substance is. Both patient and observer record any symptoms of
allergic reaction. In a double-blind challenge, neither the patient
nor the observer knows if the patient is given the food (allergen)
or the placebo.
In recent years, unproven tests such as "food cytotoxic blood tests"
and "sublingual provocation food testing" have been promoted as
supposed "diagnostic" tools to detect food allergies. FDA believes
that food cytotoxic blood tests are not supported by well-controlled
studies and clinical trials.
In food cytotoxic testing, a test tube of blood is taken from the
patient. The white cells (leukocytes) are mixed with plasma and
sterile water and placed on microscope slides coated with dried
extracts of a particular food. The reaction of the cells is then
examined under a microscope; if they change shape, disintegrate,
or collapse--or the person examining them says they do--the patient
is supposedly allergic to that particular food. Test results may be
interpreted by a "nutritional counselor" working on commission,
who recommends vitamins and minerals (often available on site)
that the patient needs to correct his or her "allergic condition." But
FDA and other experts emphasize there is no evidence that such
tests are valid in diagnosing food allergies.
Sublingual provocation food testing dates back to 1944. The test
consists of placing three drops of an allergenic extract under a
patient's tongue and waiting 10 minutes for any symptoms to
appear. When the doctor is satisfied he has determined the cause
of the symptoms, he administers a "neutralizing" dose, which is
usually three drops of a diluted solution of the same allergenic
extract. The  symptoms are then expected to disappear in the same
sequence in which they appeared. Advocates claim that if the
neutralizing dose is given before a challenge test (for instance,
eating a meal containing the offending food), the person will not
have symptoms.
But after careful study of existing data, The American Academy
of Allergy and Immunology says no controlled clinical studies
demonstrate either diagnostic or therapeutic effects of sublingual
provocation food testing. The academy concludes that use of the
tests should be reserved for experiments in well-designed trials.
If you are diagnosed with a food allergy, scrutinize food labels to
detect potential sources of food allergens. When eating out, ask
about ingredients if you are unsure about a particular food; ask to
talk to the manager of the restaurant about ingredients in specific
dishes.
Keep epinephrine with you and know how to administer it. If you
do experience a reaction, seek medical attention immediately, even
if the symptoms are mild or seem to subside. Mild symptoms may
be followed 10 to 60 minutes later by the onset of severe
problems. n

--A.H.
More Information
For more information about food allergies, contact the following
groups:

The Food Allergy Network
4744 Holly Ave.
Fairfax, VA 22030-5647
(703) 691-3179

American Academy of Allergy and Immunology
611 East Wells St.
Milwaukee, WI 53202
(414) 272-6071

Physician Referral Hotline
(1-800) 822-ASMA

The American Dietetic Association
216 W. Jackson Blvd.
Chicago, IL 60606-6995
(1-800) 877-1600

An FDA Consumer Special Report: Focus on Food Labeling, is available on this Website.