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Food Allergies

This page was reviewed or revised on Monday, July 31, 2017 2:21 PM

What is a food allergy?

A food allergy is an abnormal immune system response to a protein found in a specific food. Once a person develops a food allergy, an allergic reaction happens each time the food is eaten.

Many foods can cause allergic reactions. The most common are eggs, fish, milk, mustard, peanuts, sesame seeds, soy, sulfates, tree nuts and wheat.

For some people, eating even a tiny amount of the offending food can cause a reaction. While these reactions are often minor, in some cases they can cause serious illness or death.

For more information on the ten most common food allergens, visit the Health Canada website or call 1-800-465-7735.

What are common symptoms of a food allergy?

Food allergy reactions vary from person-to-person and can affect one or many body systems. Common symptoms include:

  • Trouble breathing, speaking or swallowing
  • A drop in blood pressure, fast heartbeat or fainting
  • Flushed face
  • Hives or a rash or red and itchy skin
  • Swelling of eyes, face, lips, tongue or throat
  • Anxious, distress, faintness or weakness
  • Cramps, diarrhea, nausea or vomiting

Anaphylactic (ana-fil-ac-tic) shock is the most severe food allergy reaction. It can happen within minutes after eating a specific food. Without immediate medical help, it can cause death. For more information about anaphylaxis visit Food Allergy Canada.

What is a food intolerance? 

Food intolerance is more common than food allergy. The immune system does not cause the symptoms of food intolerance; however, the symptoms may feel like those of a food allergy.
Example: people with lactose intolerance are unable to digest the sugar in milk, while someone with a milk allergy reacts to cow's milk protein.

People with food intolerance can sometimes eat small amounts of the offending food, while a person with a food allergy must never eat it. 
Example: someone with lactose intolerance may be able to eat some cheese, yogurt, and cow's milk, but a person with a milk allergy must avoid all sources of milk protein.

Can food allergies be prevented?

Many babies develop food allergies in the first year of life. No one is sure if it is possible to prevent babies from getting food allergies. Studies say:

Enjoy a variety of healthy foods. There is no strong research that suggests avoiding certain foods during pregnancy or breastfeeding will decrease your baby's risk of food allergies.

Breastfeed for the first 6 months of life. Breast milk is the best food for babies and may lower their risk of food allergies. Breast milk is all the food babies need until they are 6 months old. Breastfeeding should continue until babies are 2 years or older.

Wait until baby is 6 months of age to introduce solid food. Research does not show that delaying foods like peanut butter, fish and eggs past 6 months prevents food allergies.

What should I do if I think I have a food allergy?

Talk with your doctor or health care provider who can send you for tests. Do not diagnose it yourself. Symptoms of a food allergy and food intolerance can be so similar that one can be confused for the other. If you assume you have a food allergy, you may cut foods from your diet without need.

What should I do if I have a food allergy?

Allergic reactions to food can be avoided, but the only treatment is totally removing the specific food from your diet.

Here are a few tips to get you started:

  • See a registered Dietitian, who can help you plan your new diet to ensure you still get the nutrition you need.
  • Find out all the names for the food you need to avoid. For example, milk may be called "whey" or "casein."
  • Always read food labels to identify ingredients that will cause a reaction. It is important to read food labels every time because ingredients can change without notice. If you are not sure about an ingredient, call the maker and ask. Many labels have a toll-free phone number.
  • When eating out, tell your server about your allergy. Ask about ingredients and food preparation. Remember, your food can contact an allergen in the kitchen even if it is not an ingredient in the dish.
  • Beware of cross contamination. For example, the scoop used in a bulk bin of pecans may have come from the peanut bin.
  • Tell friends, family, and caregivers about the foods you need to avoid.
  • Be safe, not sorry. If you are not sure of what is in a food, do not eat it.
  • Be prepared. If you have had a severe attack, ask a doctor about carrying an EpiPen for emergencies.

It is a good idea to wear a Medic Alert identification which has information about your allergies in case of emergency.

Is it possible to outgrow a food allergy?

Food allergies are most common in young children and are often outgrown by 7 years of age. It is common for infants and toddlers to outgrow allergies to milk, egg, wheat and soy. However, allergies to peanuts, nuts, shellfish and fish are less likely to be outgrown. In some cases, symptoms become more severe every time the person is exposed to the allergen. Food allergies developed after age 3 years are less likely to be outgrown. Adult allergies are permanent. About 3.5% of adults around the world have food allergies, and 30% of these adults developed the allergy as children.

For more information on food allergies call the Registered Dietitians at 519-383-8331 or toll free at 1-800-667-1839.

Food Allergy Resources