A food allergy is an abnormal response to a food or component of food that is triggered by the immune system. It is important to make the distinction between allergy and intolerance. While an allergy involves the immune system, an intolerance affects the digestive system (abdominal pain, diarrhea) and is not life threatening.
In a food allergy, the immune system mistakenly identifies a specific food (usually a protein) or a substance in food as harmful. When the body becomes hypersensitive to a specific food, it produces several chemical substances, including histamine, which causes allergic symptoms. Health Canada has identified nine "priority food allergens" which are substances most frequently associated with allergic-type reactions:
- Sesame seeds
- Seafood (including crustaceans and shellfish)
- Tree nuts
- Wheat (and cereal products containing gluten)
Persons at risk
There are two key factors to consider when dealing with a food allergy:
Food allergies are more common in young children. Recent estimates reveal that 6% of children are thought to suffer from food allergies, compared with 3 to 4% of adults. Many food allergies tend to disappear with age (milk, soy, wheat, eggs). Some people however, will have food allergies for the rest of their lives.
Children whose parents have a food allergy are 50 to 70% more likely to develop an allergy. Additionally, the risk of food allergies increases when there is a family history of hay fever, eczema or asthma.
For some, food allergies cause unpleasant albeit non-life threatening reactions. For others however, reactions can be more serious. The most common symptoms are tingling on the tongue and itchy skin. Breathing difficulties, diarrhea, vomiting as well as swelling of the lips, face and throat are also quite common. Some may experience confusion or loss of consciousness.
The most severe reaction is known as anaphylactic shock which is a whole-body reaction (obstructed airway, significant swelling). Immediate emergency treatment, in the way of a dose of epinephrine (Epipen®, Twinject®), is critical. This type of reaction may be fatal.
In addition to a medical examination, a journal detailing what one eats, along with symptoms, can help identify a food allergy as well as the foods responsible for the allergy. Tests are also available and can provide some answers:
Droplets containing allergens are placed on the back or forearms. By lightly picking the skin with a needle, the substances are able to penetrate the skin. As a result, those with allergies develop localized swelling.
Blood tests are used to measure the level of antibodies in the blood. Samples are used to test a wide range of foods.
In the case of a mild allergy, antihistamines, which are sold over the counter in pharmacies, are generally recommended. Persons with more severe allergies must have injectable epinephrine on them at all times (Epipen®, Twinject®) in case they come into contact with the food allergen.
The only way to avoid an allergic reaction is to avoid the allergen. This, however, is not always easy. If you have a food allergy, it is imperative that you read product labels and ingredient lists very carefully. It is important to remember that an allergen can have several names (ex: dairy products and casein). It is therefore very important that you learn as much as you can about the derivatives of the foods to which you are allergic. It is also important for those with food allergies to watch what they eat when they go out to restaurants.
Breastfeeding can protect a baby from developing allergies later on in life. Also, creating awareness and informing those who have frequent contact with a child who has food allergies is key to preventing potentially avoidable incidences. Wearing a medical alert bracelet is recommended.
For more information:
Allergy/Asthma Information Association
Educational Community Resources
Food Allergy Information and Support
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.