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Food allergy is an immune system reaction that occurs
soon after eating a certain food. Even a tiny amount of the
allergy-causing food can trigger signs and symptoms such as
digestive problems, hives or swollen airways. In some
people, a food allergy can cause severe symptoms or even a
life-threatening reaction known as anaphylaxis.
Food allergy affects an estimated 6 to 8 percent of children
under age 3 and up to 3 percent of adults. While there's no
cure, some children outgrow their food allergy as they get
It's easy to confuse a food allergy with a much more common
reaction known as food intolerance. While bothersome, food
intolerance is a less serious condition that does not involve
the immune system, and is triggered by several different
mechanisms that are distinct from the immunological reaction
responsible for food allergy.
Food Allergy in India and Asia
Although we often think of allergy as a Western disease, in reality it’s
fast becoming a global problem. In many Western nations, allergy
rates stand at around 40% of the population – or sometimes higher. It
may surprise you, but India is not far behind, with an estimated 25%
of the population now having at least one allergic condition.
India, with a diverse and unique food culture, has acquired its own
portfolio of allergens too. Granted, nuts and wheat and dairy and
others can be a problem to south Asians, but research led by
Professor Mahesh PA, Director at Allergy Asthma Associates in
Mysore, India, has uncovered many others – with brinjal (aubergine),
cucumber, lady’s finger (okra) and papaya among the most common
foods causing clinical symptoms in population samples from Mysore
City and from Bangalore.
With a population of well over a billion, food allergy could become an
enormous problem in India. Some estimates suggest up to 3% of
Indians may already have food allergies, the majority under 40 years
of age. Food allergies cause roughly 30,000 emergency treatments
and 100 to 200 deaths per year in the nation. Up to 3 million Indians
may have peanut allergy alone.
FOOD ALLERGY FACTS
Food allergy is not common but can be serious.
Food allergy differs from food intolerance, which is
far more common.
The more frequent types of food allergies in adults
differ from those in children.
Children can outgrow their food allergies, but
adults usually do not.
The diagnosis of food allergy is made with a
detailed history, the patient's diet diary, or an
Food allergy is treated primarily by dietary
MECHANISM OF ALLERGY
The protein in the food is the most common allergic component.
These kinds of allergies occur when the body's immune system
mistakenly identifies a protein as harmful. Some proteins or
fragments of proteins are resistant to digestion and those that are
not broken down in the digestive process are tagged by
the Immunoglobulin E (IgE). These tags fool the immune system
into thinking that the protein is an invader. The immune system,
thinking the organism (the individual) is under attack, sends white
blood cells to attack, and that triggers an allergic reaction. These
reactions can range from mild to severe.
Allergic responses include dermatitis, gastrointestinal and
respiratory distress, including such life-
threatening anaphylactic responses as biphasic
anaphylaxis and vasodilation; these require immediate emergency
intervention. Individuals with protein allergies commonly avoid
contact with the problematic protein. Some medications may
prevent, minimize or treat protein allergy reactions. There is no
Conditions caused by food allergies are classified into 3 groups according to the mechanism of the
1. IgE-mediated (classic):
Type-I immediate hypersensitivity reaction
Oral allergy syndrome
2. IgE and/or non-IgE-mediated:
Allergic eosinophilic oesophagitis
Allergic eosinophilic gastritis
Allergic eosinophilic gastroenteritis
3. Non-IgE mediated:
Food protein-induced Enterocolitis syndrome (FPIES)
Food protein proctocolitis/proctitis
Food protein-induced enteropathy. An important example is Celiac disease, which is an adverse
immune response to the protein gluten.
Milk-soy protein intolerance (MSPI) is a non-IgE mediated allergic response to milk and/or soy
protein during infancy and early childhood. Symptoms of MSPI are usually attributable to food
protein proctocolitis or FPIES.
Heiner syndrome — lung disease due to formation of milk protein/IgG antibody immune
complexes (milk precipitins) in the blood stream after it is absorbed from the GI tract.
What causes food allergies?
Food allergies are caused when the immune system (the body’s defence against
infection) mistakenly treats proteins found in food as a threat to the body, when
in fact they should be harmless.
It then releases a number of chemicals to prevent what it sees as an infection
taking hold. It is these chemicals that cause the symptoms of an allergic
Any food could cause an allergic reaction, but there are certain foods that are
responsible for most food allergies.
In children, the foods that most commonly cause an allergic reaction are:
Fish and Shellfish
•Eye discomfort and redness
•Joint pain or muscle pain
•Nausea or vomiting
•Blood in stool
•Eye discomfort and redness
•Foot pain or ankle pain
•Foot swelling or leg swelling
•Low back pain
•Nausea or vomiting
•Numbness or tingling in hands
•Pelvic pain: female
•Pelvic pain: male
•Shortness of breath
Peanut allergies tend to be lifelong, although studies indicate
that approximately 20 percent of children with peanut allergy
do eventually outgrow their allergy
Trace amounts of peanut can cause an allergic reaction.
Casual contact with peanuts, such as touching peanuts or
peanut butter residue, is less likely to trigger a severe
reaction. Casual contact becomes a concern if the area that
comes into contact with peanuts then comes into contact with
the eyes, nose or mouth
An estimated 25-40 percent of people who have peanut
allergy also are allergic to tree nuts. In addition, peanuts and
tree nuts often come into contact with one another during
manufacturing and serving processes. For these reasons,
allergists usually tell their patients with peanut allergy to avoid
tree nuts as well.
The federal Food Allergen Labeling and
Consumer Protection Act (FALCPA) requires
that all packaged food products sold that contain
peanuts as an ingredient must list the word
―Peanut‖ on the label.
Read all product labels carefully before
purchasing and consuming any item. Ingredients
in packaged food products may change without
warning, so check ingredient statements carefully
every time you shop. If you have questions, call
As of this time, the use of advisory labels (such as
―May Contain‖) on packaged foods is
voluntary, and there are no guidelines for their
Avoid foods that contain peanuts or
any of these ingredients:
Cold pressed, expeller pressed or
extruded peanut oil
Mandelonas (peanuts soaked in almond
Peanut protein hydrolysate
Peanut is sometimes
found in the following:
(e.g., pastries, cookies)
TREE NUT ALLERGIES
Tree nuts include, but are not limited to, walnut,
almond, hazelnut, cashew, pistachio, and Brazil
nuts. These are not to be confused or grouped
together with peanut, which is a legume, or seeds,
such as sunflower or sesame.
A person with an allergy to one type of tree nut has
a higher chance of being allergic to other types.
Therefore, many experts advise patients with
allergy to tree nuts to avoid all nuts. Patients may
also be advised to also avoid peanuts because of
the higher likelihood of cross-contact with tree
nuts during manufacturing and processing.
Tree nuts are sometimes found in the following:
Black walnut hull extract (flavoring)
Natural nut extract
Nut distillates/alcoholic extracts
Nut oils (e.g., walnut oil, almond oil)
Walnut hull extract (flavoring)
Some Unexpected Sources of Tree Nuts
Tree nut proteins may be found in
cereals, crackers, cookies, candy, chocolates, energy
bars, flavored coffee, frozen
desserts, marinades, barbeque sauces and some cold
cuts, such as mortadella.
Some alcoholic beverages may contain nut flavoring
and should be avoided. Since these beverages are not
currently regulated by FALCPA, you may need to call
the manufacturer to determine the safety of ingredients
such as natural flavoring.
Allergy to cow’s milk is the most common food allergy
in infants and young children. Symptoms of a milk
allergy reaction can range from mild, such as hives, to
severe, such as anaphylaxis. Therefore it is advised
that people with milk allergy have quick access to an
epinephrine auto-injector (such as an EpiPen®, Auvi-
Q® or Adrenaclick®) at all times. To prevent a
reaction, strict avoidance of cow’s milk and cow’s milk
products is essential.
Sensitivity to cow’s milk varies from person to person.
Some people have a severe reaction after ingesting a
tiny amount of milk. Others have only a mild reaction
after ingesting a moderate amount of milk. Reactions
to milk can be severe and life-threatening
Differences between Milk Allergy
and Lactose Intolerance
Milk allergy should not be confused with lactose intolerance.
A food allergy is an overreaction of the immune system to a
specific food protein. When the food protein is ingested, in
can trigger an allergic reaction that may include a range of
symptoms from mild symptoms
(rashes, hives, itching, swelling, etc.) to severe symptoms
(trouble breathing, wheezing, loss of consciousness, etc.). A
food allergy can be potentially fatal.
Unlike food allergies, food intolerances do not involve the
immune system. People who are lactose intolerant are
missing the enzyme lactase, which breaks down lactose, a
sugar found in milk and dairy products. As a result, lactose-
intolerant patients are unable to digest these foods, and may
experience symptoms such as nausea, cramps, gas, bloating
and diarrhea. While lactose intolerance can cause great
discomfort, it is not life-threatening.
Avoid foods that contain milk or any of these
Butter, butter fat, butter oil, butter acid,
Caseinates (in all forms)
Lactalbumin, lactalbumin phosphate
Milk protein hydrolysate
Sour cream, sour cream solids
Sour milk solids
Whey (in all forms)
Whey protein hydrolysate
Milk is sometimes found in the following:
Artificial butter flavor
Lactic acid starter culture and other bacterial
Luncheon meat, hot dogs, sausages
Some Unexpected Sources of
Deli meat slicers are frequently used for both meat and cheese
Some brands of canned tuna fish contain casein, a milk protein.
Many non-dairy products contain casein (a milk derivative), listed on
the ingredient labels.
Some specialty products made with milk substitutes (i.e., soy-, nut-
or rice-based dairy products) are manufactured on equipment
shared with milk.
Some meats may contain casein as a binder. Check all labels
Shellfish is sometimes dipped in milk to reduce the fishy odor. Ask
questions about the risk of milk contact when purchasing shellfish.
Many restaurants put butter on steaks after they have been grilled
to add extra flavor. The butter is not visible after it melts.
Some medications contain milk protein.
Egg allergy is one of the most common food
allergies in children, second only to milk
allergy. Symptoms of an egg allergy reaction
can range from mild, such as hives, to
severe, such as anaphylaxis.
While the whites of an egg contain the
allergenic proteins, patients with an egg
allergy must avoid all eggs completely. This is
because it is impossible to separate the egg
white completely from the yolk, causing
a cross-contact issue.
Egg Allergy and Vaccines
Some vaccines contain egg protein. The
recommendations of the American Academy of
Pediatrics (AAP) acknowledge that the MMR
vaccine (measles-mumps-rubella) can be
safely administered to all patients with egg
Influenza vaccines usually contain a small
amount of egg protein. If you or your child is
allergic to eggs, speak to your doctor before
receiving a flu shot.
Avoid foods that contain eggs or any of
Albumin (also spelled albumen)
Egg (dried, powdered, solids, white, yolk)
Meringue (meringue powder)
Eggs are sometimes found in the
•Eggs have been used to create the foam or topping on specialty coffee drinks and are
used in some bar drinks.
•Some commercial brands of egg substitutes contain egg whites.
•Most commercially processed cooked pastas (including those used in prepared foods
such as soup) contain egg or are processed on equipment shared with egg-containing
pastas. Boxed, dry pastas are usually egg-free, but may be processed on equipment
that is also used for egg-containing products. Fresh pasta is sometimes egg-free, too.
Read the label or ask about ingredients before eating pasta.
•Egg wash is sometimes used on pretzels before they are dipped in salt.
Some Unexpected Sources of Egg
A wheat allergy can present a challenge for the
diet as well as for baking, because wheat is the
nation’s predominant grain product. Someone
on a wheat-restricted diet can eat a wide
variety of foods, but the grain source must be
something other than wheat. In planning a
wheat-free diet, look for alternate grains such
amaranth, barley, corn, oat, quinoa, rice, rye, a
nd tapioca. When baking with wheat-free
Differences between Wheat Allergy and Celiac
Disease or Gluten Intolerance
Celiac disease which affects the small intestine, is
caused by an abnormal immune reaction to
gluten. Usually diagnosed by a gastroenterologist,
it is a digestive disease that can cause serious
complications, including malnutrition and intestinal
damage, if left untreated. Individuals with celiac
disease must avoid gluten, found in wheat, rye,
barley and sometimes oats.
People who are allergic to wheat often may
tolerate other grains. However, about 20 percent
of children with wheat allergy also are allergic to
other grains. Be sure to ask your doctor whether
foods containing barley, rye, or oats are safe for
you or your child to eat.
Avoid foods that contain wheat or any of these ingredients:
•Flour (all purpose, bread, cake, durum, enriched, graham, high gluten, high protein, instant, pastry, self-rising, soft
wheat, steel ground, stone ground, whole wheat)
•Hydrolyzed wheat protein
•Matzoh, matzoh meal (also spelled as matzo, matzah, or matza)
•Vital wheat gluten
•Wheat (bran, durum, germ, gluten, grass, malt, sprouts, starch)
•Wheat bran hydrolysate
•Wheat germ oil
•Wheat protein isolate
•Whole wheat berries
Soybean allergy is one of the more common
food allergies, especially among babies and
children. Approximately 0.4 percent of children
are allergic to soy.
Soybeans are a member of the legume
family, which include plant species that bear
seed pods that split upon ripening. Some
examples of other legumes include
beans, peas, lentils and peanut. People with a
soy allergy are not necessarily allergic to other
Avoid foods that contain soy or any
of these ingredients:
•Soy (soy albumin, soy cheese, soy
fiber, soy flour, soy grits, soy ice
cream, soy milk, soy nuts, soy
sprouts, soy yogurt)
•Soybean (curd, granules)
(concentrate, hydrolyzed, isolate)
•Textured vegetable protein (TVP)
Soy is sometimes found in the
Sources of Soy
Soybeans and soy products
are found in many foods,
including baked goods,
canned tuna and meat,
cereals, cookies, crackers,
high-protein energy bars and
snacks, infant formulas, low-
fat peanut butter, processed
meats, sauces, and canned
broths and soups.
FISH AND SHELLFISH
Salmon, tuna and halibut are the most
common kinds of finned fish to which people
are allergic. More than half of all people who
are allergic to one type of fish also are allergic
to other fish, so allergists often advise their
fish-allergic patients to avoid all fish.
There are two kinds of shellfish: crustacea
(such as shrimp, crab and lobster) and
molluscs (such as clams, mussels, oysters and
Some Unexpected Sources of
Caesar salad and Caesar dressing
Imitation or artificial fish or shellfish
(surimi, also known as ―sea legs‖ or ―sea
sticks,‖ is one example)
Caponata, a Sicilian eggplant relish
Avoid foods that contain shellfish or
any of these ingredients:
Crawfish (crawdad, crayfish, ecrevisse)
Lobster (langouste, langoustine, Moreton
bay bugs, scampi, tomalley)
Shrimp (crevette, scampi)
Shellfish are sometimes found in the
Seafood flavoring (e.g., crab or clam
Keep the following in mind:
•If you have seafood allergy, avoid seafood restaurants. Even if you order a non-
seafood item off of the menu, cross-contact is possible.
•Asian restaurants often serve dishes that use fish sauce as a flavoring base.
Exercise caution or avoid eating there altogether.
•Shellfish protein can become airborne in the steam released during cooking and
may be a risk. Stay away from cooking areas.
•Carrageenan, or "Irish moss,‖ is not shellfish. It is a red marine algae that is used
in a wide variety of foods, particularly dairy foods, as an emulsifier, stabilizer, and
thickener. It appears safe for most individuals with food allergies.
•Allergy to iodine, allergy to radiocontrast material (used in some radiographic
procedures), and to shellfish are not related. If you have an allergy to shellfish, you
do not need to worry about cross reactions with radiocontrast material or iodine.
While only eight foods (milk, egg, peanut, tree nuts, fish, shellfish, wheat, and soy)
account for approximately 90 percent of all food-allergic reactions, a person can be
allergic to virtually any food.While the list below is not exhaustive, allergic reactions
have been reported to:
Meat (beef, chicken, mutton, and pork)
Seeds (sesame, sunflower, and poppy being the most common)
Spices (caraway, coriander, garlic, mustard, etc.)
Other common causes of severe reactions include:
Allergic reactions to fresh fruits and vegetables, such as
apple, carrot, peach, plum, tomato and banana, to name a few, are often
diagnosed as Oral Allergy Syndrome.
The mainstay of treatment for food allergy is total
avoidance of the foods that have been identified as
allergens. For people who are extremely
sensitive, avoidance includes avoiding touching or
inhaling the problematic food.
If the food is accidentally ingested and a systemic
occurs, then epinephrine should be used. It is possible
that a second dose of epinephrine may be required for
severe reactions. The person should then be
transported to the emergency room, where additional
treatment can be given.
include: antihistamines, and steroids. In a severe
case, neither steroids nor antihistamines are life
saving and its use should be limited to adjuvant
For food allergy, desensitization through sublingual, oral or epicutaneous
immunotherapy is possible for a subset of people, but not all.While not a
cure, this program enables food allergic children and adults to consume
foods that they were allergic to previously, without any allergic reaction.
Desensitization approaches for food allergy are generally at the
research stage. They include:
Oral immunotherapy, which involves building up tolerance by eating a
small amount of (usually baked) food;
Sublingual immunotherapy, which involves placing a small drop of milk
or egg white under the tongue;
Epicutaneous immunotherapy, which injects the allergic food under the
Monoclonal anti-IgE antibodies, which non-specifically reduce the body's
capacity to produce an allergic reaction; and
use of probiotics;
helminthic therapy; and
a drug to suppress Toll-like receptor 9 (TLR9).
To recap, be sure to:
Learn all you can about avoiding allergens. Read food
labels carefully and don’t hesitate to ask questions when eating
away from home. Vigilance is your first line of defense against
Have your medication with you wherever you go.
Talk to your allergist about when and how to use emergency
Make sure prescriptions are up-to-date.
Wear medical identification (e.g., bracelets, other jewelry) at all
Don’t delay using your epinephrine while waiting to see if your
symptoms improve! Use your emergency medications as
Get to an emergency room for evaluation and further treatment
right away – even if your medication has stopped the reaction.
Epinephrine is not a “foolproof” treatment. Don’t take chances
by eating a problem food.
Probiotic drinks and yoghurts promote gut immunity, meaning you