What is an allergy
and intolerance?
Diagnosing Food
Allergies
Milk Allergy
Egg Allergy
Peanut Allergy
Wheat Allergy
Food Additives
Common Questions and
Answers about Allergies
What is an allergy and intolerance?
Food allergy or “hypersensitivity” is defined as an immune-system
response to a food protein that the body identifies as foreign. As such, it
is different from a food intolerance (such as lactose intolerance), which is
an adverse reaction to a food that results in symptoms, but is not caused by
a reaction of the immune system.
Allergic reactions can take different forms.
Most common are:
Systemic: anaphylaxis is an immediate and
often severe allergic response that involves
two or more body systems. Symptoms can include shortness
of breath, wheezing, hives, swelling (of the lips and face),
vomiting, lowered blood pressure, and dizziness. Anaphylaxis
can progress to anaphylactic shock, a potential life-threatening
condition.
Digestive: vomiting, abdominal pain, diarrhea, malabsorption
of nutrients
Respiratory: runny nose, nasal congestion, difficulty
breathing, wheezing
Skin: rash, hives, eczema
Diagnosing food allergies
Methods used to diagnose allergies accurately include:
Double-blind placebo/controlled-food challenge:
In this test, the allergen or placebo (blank/dummy)
is given to a person by a researcher and neither the patient
nor the researcher knows which is which. The patient's reaction
and symptoms are monitored by the researcher.
Elimination diet: With this method, allergenic
foods are eliminated from the diet for a 2-week period and
are then slowly reintroduced to try and identify which foods
are causing symptoms. This process of elimination should be
followed under medical supervision. The testing period should
not exceed 2 weeks, since nutritional deficiencies may result.
Skin test: Also known as “prick tests”,
these are widely used to diagnose food allergy. A small amount
of an allergen is introduced to the skin by pricking the skin
with a small needle. The skin is then monitored for a reaction.
Skin tests are not 100% accurate and false reactions may occur.
These tests are especially inaccurate in diagnosing allergies
in infants.
Common Types of Food Allergies
Although any number of foods can cause allergic reactions, there are several
that have proven to be more widespread than others.
Milk allergy
Cow’s milk allergy occurs in about 2 or 3 of every 100 infants – although
most grow out of it by the time they are 3 years old. Infants at higher risk
of developing milk allergy include those cases where one or both parents (or
a sibling) had milk allergy as an infant. Symptoms of milk allergy include
vomiting, diarrhea and insufficient weight gain. Skin or chest symptoms or
blood in the stools may also occur.
Milk ingredients are not always clearly indicated as such on food labels. If
you see any of the following words on a label, it means the food contains milk
protein.
- milk
- condensed milk
- evaporated milk
- milk powder
- butter
- milk solids
- cheese
- cottage cheese
- sour cream
- yogurt
- buttermilk
- curd
- cream
- cream cheese
- quark
- ice cream
- sherbet
- feta/ricotta
- casein
- sodium caseinate
- potassium caseinate
- whey
- lactoglobulin
- lactose
Helpful products for milk allergy: Rice milk/beverage
is a common substitute for cow’s milk. It does not contain
the same amounts of nutrients as cow’s milk so calcium
and vitamin D supplements are often needed. Fortified soy beverage
is a good substitute for cow’s milk as it provides the
same amount of protein and other nutrients such as calcium
and vitamin D. However, most individuals who are allergic to
cow’s milk are also allergic to soy protein. For this
reason, it is advised only to try soy beverage under the supervision
of a physician. Although some individuals who are allergic
to cow’s milk can tolerate goat’s milk, many are
allergic to both cow’s and goat’s milk. Similarly
to soy beverage, it is recommended that goat’s milk is
only tried under the supervision of a physician. There are
also hypoallergenic infant formulas available for bottle feeding.
Other dairy free foods include non dairy chocolate (carob),
non-dairy cheese, non-dairy yogurt and non-dairy ice cream.
Egg allergy
Common in young children, delaying the introduction of egg
yolks until an infant is at least 6 months old is important.
Egg whites should not be introduced until the infant is at
least 1 year old. For children and adults with egg allergy,
avoiding a whole egg is fairly easy. But because eggs are
so widely used as an ingredient, it is often much harder
to avoid foods that may contain eggs. For example, some
common foods that contain eggs include custards, egg nog,
Caesar salad dressing, cakes, cookies, pies, pancakes,
waffles and battered foods. Eggs may also be used in consommé soup and soft drinks
(like root beer), where they are used as a clarifier. Egg beaters®,
while sold as an egg substitute, are not egg-free and should not be consumed
by people with an egg allergy. Some vaccinations also include egg protein.
Your doctor will be able to give you information if you are concerned about
egg allergy and vaccines.
If you see any of the following words on a food label, it contains egg protein:
- albumin
- egg
- baking powder
- ovalbumin
- egg white
- ovomucin
- egg yolk
- ovovitellin
- globulin
- livetin
- mayonnaise
- egg powder
- ovoglobulin
- egg protein
- ovomucoid
- frozen egg
- pasteurized egg
- simplese
- vitellin
Helpful products for egg allergy: While there
are no alternatives that can replace the taste of eggs, there
are some substitutes that can duplicate its cooking qualities.
Many egg-free recipes substitute a mixture of vegetable oil,
baking powder and water for the egg. Egg substitutes and egg
white substitutes are also available. Be sure to check the
ingredients label carefully, as some egg substitutes still
contain egg whites.
Peanut allergy
Unlike milk and egg allergies, peanut allergies generally persist beyond childhood.
This type of allergy is common, as well as being one of the most severe – often
the cause of anaphylactic shock. While a peanut allergy does not necessarily
extend to all nuts, anyone who has had a previous anaphylactic reaction to
peanuts should avoid all nuts to be safe. Pure peanut oil should also be
avoided, since, although theoretically free of peanut proteins, may nevertheless
contain trace amounts. Peanut oil is widely used in many restaurants (particularly
Thai and Chinese), so you may choose to avoid these restaurants altogether.
Be sure to read food labels carefully for foods that ‘may contain’ peanuts
and avoid these. Fortunately, a growing number of peanut-free products are
available that provide more options for families dealing with nut allergies.
Some great examples include: No Nuts Pea Butter, Quaker Peanut-Free Granola
Bars and for occasional treats Nestle Snack Size Chocolate Bars and Mars
Chocolate Bars.
Wheat allergy
While not common, grain allergies do occur, with wheat as the most likely cause.
This allergy is an adverse reaction to the protein component of wheat. It
is different than celiac disease in which affected people cannot tolerate
gluten (a protein found in many grains including wheat, oats, rye and barley).
Celiac disease also requires significant lifelong dietary changes, beyond
eliminating wheat from the diet. Read our gluten-free
guidelines.
Wheat is found in many foods, including breads,
cereals, pastas, cakes, luncheon meats and sausage – virtually
anything that contains wheat flour. Because wheat flour is
often fortified with vitamins such as riboflavin, thiamin,
niacin and iron, the elimination of wheat from the diet can
result in a nutrient deficiency unless replaced with other
foods, including alternate flours such as rye, corn, or rice.
Food additives
While their effects can be uncertain, food additives are often blamed or suspected
for causing allergic symptoms. In children, they are sometimes blamed for
changes in behaviour. Food additives include artificial colourings and flavours,
preservatives (such as sulfur dioxide, butylated hydroxytoluene (BHT) and
butylated hydroxyanisole (BHA).), nitrates and nitrites, monosodium glutamate
(MSG) as well as artificial sweeteners (such as aspartame or cyclamate).
Many scientific studies have been conducted on how these additives may affect
allergies and health, but few certain conclusions have been reached. Since many of
the foods containing these ingredients are low in overall nutritional value,
limiting these foods in the diet is prudent.
Food Allergies text pages reprinted with permission
from Better Baby Food, by Daina Kalnins and Joanne Saab, Robert
Rose Inc. 2001.
Common
Questions and Answers About Allergies
What exactly is lactose intolerance and
what can I do about it?
Lactose intolerance is the inability to digest significant amounts of lactose,
the predominant sugar in milk. This inability results from a shortage of the
enzyme lactase, which is normally produced in the small intestine. The lactase
breaks down milk sugar into simpler forms that can be absorbed into the bloodstream.
When there is not enough lactase to digest the amount of lactose consumed,
it may lead to nausea, cramps, bloating, gas and diarrhea, which begin
30 minutes to 2 hours after eating. The severity of the symptoms varies depending
on the amount of lactose each person can tolerate. For most people, this condition
develops naturally over time. After the age of about 2 years, the body begins
to produce less of the enzyme lactase.
Lactose intolerance can be fairly easy to manage.
Here are a few helpful tips:
- If you can tolerate moderate amounts of lactose, mix lactose-containing foods
with other foods at mealtime to help with digestion.
- Eat smaller portions of lactose-containing foods.
- Choose dairy foods with active cultures such as yogurt because these "good" bacteria
may help digestion.
- Aged cheeses such as Colby, Swiss, Parmesan and Cheddar may be more tolerable
because a lot of the lactose is lost in processing.
- Look for lactose-reduced or lactose-free dairy products.
- Take a lactase supplement before eating foods with lactose.
Milk and other dairy products are major sources
of calcium. Essential in the growth and repair of bones throughout
life, calcium is particularly important in preventing osteoporosis.
If you are unable to enjoy milk and dairy products, be sure
to include non-dairy alternatives rich in calcium, like broccoli,
tofu (processed with calcium salts), and fish with soft and
edible bones including salmon and sardines. You may also want
to consider supplements.
What foods should I avoid if I am sensitive
to sulphites?
Sulphites naturally occur in food but are also a food additive used in foods
as a preservative. To avoid sulphites, read product labels carefully and avoid
foods that contain sulphites and sulphite derivatives.
If you see any of the following words on a food label, it contains sulphites:
- potassium bisulphate
- potassium metabisulphite
- sodium bisulphate
- sodium dithionite
- sodium metabisulphite
- sodium sulphite
- sulfur dioxide
- sulphiting agents
- sulphurous acid
Common foods that contain sulphites:
- alcoholic and non-alcoholic beer, cider and wine
- baked goods
- bottled lemon and lime juice and concentrate
- condiments, dressings, gravy, sauces, soups, soup mixes
- dried herbs, spices and tea
- canned and frozen produce including mushrooms, sliced apples, olives, peas,
peppers, pickles, pickled onions, tomatoes
- dried fruit
- fresh grapes
- fresh lettuce
- fruit and vegetable juices such as grape and sparkling grape
- glazed and glaceed fruits
- potatoes (dehydrated, mashed, peeled, and pre-cut)
- fish
- gelatin, jams, jellies, marmalade and pectin
- processed foods including cheese, deli meats, frozen French fries, frozen
dough, hot dogs and sausages
- snack foods including trail mix, fruit bars, tortilla and potato chips, soft
drinks, candy and chocolate
- soy products
- sugar syrups
- vinegar, wine vinegar
What is Oral Allergy Syndrome?
Oral Allergy Syndrome (OAS) is a type of cross-reactivity allergy that occurs
in individuals who are highly sensitive to particular pollens including ragweed
and birch tree pollen. This cross-reactivity happens because plants from
the same family as ragweed and birch tree create similar allergic reactions.
During seasons that ragweed and birch tree pollinate, individuals may experience
rapid onset of itching in the mouth and throat and mild swelling after eating
foods from the same plant family. In some cases, OAS may trigger severe throat
swelling and/or severe systemic allergic reactions (anaphylaxis), causing
breathing difficulties and possibly death. If during allergy season, individuals
notice any OAS symptoms, it is recommended to avoid these foods until hay
fever subsides. Cooking these foods can help to avoid a reaction.
Individuals with ragweed allergies may experience
OAS symptoms after consuming the following foods:
- bananas
- chamomile tea
- cucumbers
- echinacea
- melons
- sunflower seeds
- zucchini
Individuals with birch tree pollen allergies
may experience OAS symptoms after consuming the following foods:
- almonds
- apples
- carrots
- cherries
- hazelnuts
- kiwis
- peaches
- pears
How do I know if I have a food allergy?
It is important to work with your allergist and/or physician to properly diagnose
a food allergy. To help diagnose a food allergy, keep a food diary for 1 to
2 weeks of everything you eat, what symptoms you experience and how long after
eating them they occur. Along with this information, allergy testing and a
physical examination if symptoms are present, your allergist and/or physician
can help determine which food is causing the allergic reaction.
Where can I find more resources and information
on allergies?
Health Canada (Food Allergy Factsheets) www.hc-sc.gc.ca
Allergy/Asthma Information Association www.aaia.ca
Food Allergy and Anaphylaxis Network www.foodallergy.org
American Academy of Allergy Asthma & Immunology www.aaaai.org
Anaphylaxis Canada www.anaphylaxis.ca
Canadian Society of Allergy and Clinical Immunology www.csaci.medical.org
www.peanutallergy.com
www.abcpeanut.com
www.glutenfreediet.ca
www.celiac.ca
How can I access a dietitian to talk
about food allergies?
- Ask Our Nutritionists.
Send your questions to our online nutritionists.
- Call Dial-A-Dietitian (available only in BC) in Greater Vancouver at 604-732-9191
or toll free in BC at 1-800-667-DIET to talk to an allergy dietitian.
- Visit www.dietitians.ca to
locate a consulting dietitian/nutritionist in your community or see the Yellow
Pages under Dietitians or Registered Dietitian.
- Visit your hospital outpatient nutrition department.
How can I access a pharmacist to talk
about allergy medications or treatment options?
- Ask Our Pharmacist.
Send your questions to our online pharmacists.
- Stop by our pharmacies to talk directly with our pharmacists.
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