Everything You Need to Know About Food Allergies

Food allergies in kids are increasingly common—according to Food Allergy Canada, a patient education and advocacy organization, six to eight percent of kids under age three have food allergies, with peanut allergies affecting two in every 100 Canadian children.

What is a food allergy?

A food allergy is an abnormal immunological response to a food—your immune system thinks a normally harmless food, like peanuts, is an invader and, in response, produces something called immunoglobulin E antibodies (commonly called IgE antibodies), which set off symptoms that can range from mild to severe.

To become allergic to a food, kids have to be exposed to the allergen in some way first, by unknowingly eating it, being exposed through broken skin (such as eczema) or coming in contact with it in other ways that are not yet well understood by experts.

What are the symptoms of a food allergy?

Symptoms of a food allergy include hives, vomiting, difficulty breathing, swelling of the lips, tongue or throat, or, more seriously, a drop in blood pressure or cardiac arrest. A severe allergic reaction is called anaphylaxis. Here's a more in-depth look at the symptoms of a food allergy and how to treat them. 

What are the common food allergies in kids?

Common food allergens are peanuts, tree nuts (like cashews, almonds and hazelnuts), eggs, milk, wheat, soy, sesame, seafood, sulphites (a preservative) and mustard. But technically, you can be allergic to any food protein. Some allergies are more common in kids, and can be difficult to navigate. Here's a more detailed look at some common food allergens:

• Everything you need to know about a peanut allergy
• Everything you need to know about a milk allergy
• Everything you need to know about a tree nut allergy
• Everything you need to know about an egg allergy
• Everything you need to know about a wheat allergy
• Everything you need to know about a sesame allergy

What is the difference between a food allergy and an intolerance?

A food intolerance occurs when you have difficulty digesting a food, but is not life-threatening. A common food intolerance is lactose intolerance, where your body cannot properly digest lactose (the sugar in milk) due to a lack of lactase (the enzyme that breaks it down).

If your kid is allergic to milk, being exposed to even a small amount can cause a potentially life-threatening reaction that may involve the skin and respiratory, cardiovascular and gastrointestinal systems. In contrast, lactose intolerance only affects the gastrointestinal system, and many people can still tolerate small amounts of lactose.

Another common food intolerance is celiac disease.

Can you prevent food allergies?

There's no way to completely prevent food allergies, but research shows that early introduction—between four and 11 months old—can reduce the likelihood of developing an allergy.

A landmark randomized controlled trial published in 2015 found that children who were at high risk of developing a peanut allergy—those with severe eczema or an egg allergy—had a three percent chance of becoming allergic by age five if they ate six grams of peanut a week compared to a 17 percent chance if they ate none.

“If we get the food in early enough, the gut will help the immune system develop a tolerance, where there’s no allergic reaction against the food,” explains Harold Kim, an allergist in Kitchener, Ont., and president of the Canadian Society of Allergy and Clinical Immunology. “Based on that landmark study, we now recommend that peanuts be introduced early. Many of us have extrapolated to other foods as well, including milk, eggs and tree nuts.”

Is there a cure for food allergies?

Currently, there isn't a cure for food allergies, but a treatment called oral immunotherapy has been shown to increase the amount of food a person can eat before they have an allergic reaction. In oral immunotherapy, the patient consumes a gradually increasing amount of the food on a daily basis in an effort to change the immune response.“The research behind immunotherapy is very good in terms of quality, so more of us are doing it,” says Kim.

Oral immunotherapy for the treatment of allergies hasn’t yet been approved by Health Canada or the Food and Drug Administration, but some allergists perform it and patients may have to pay out of pocket or join a clinical trial to receive treatment. The therapy carries the risk of a reaction and definitely should not be tried at home without a doctor's supervision. Research into skin patch immunotherapy has also shown promise.

“There may also be peanut patch immunotherapy coming, where you apply the peanut antigen to the skin. Hopefully, it will be available in the next few years,” says Kim.