However, a small percentage of people have been diagnosed with food allergies or food intolerances and have to choose their foods more carefully.

When it comes to healthy eating, it’s important not to “cut out” foods from your diet without a medical diagnosis of any food-related symptoms or reactions you may experience.

This article explains what food allergies and food intolerances are, and offers advice on getting a proper diagnosis, to ensure the eating choices you make are healthy ones.

Food Allergies vs. Food Intolerances
The biggest difference between food allergies and food intolerances is that a person’s response to a food allergy involves the immune system, while food intolerances do not.

• Food allergies occur when the body’s immune system overreacts to an ingredient or nutrient in a food. 
• A food intolerance doesn't involve the immune system. Instead, the symptoms of a food intolerance happen when the body cannot break down or digest a food, or part of a food.

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The immune system is designed to protect us from harmful “invaders” or elements that are present in the world around us. In the case of a food allergy, the immune system mistakenly views a food or food ingredient as something that is harmful. In response, it launches defences to try and protect the body.

Sometimes, it can be confusing to understand the differences between food allergies and intolerances. Even the experts find it difficult to explain at times.

Dr. Catherine Field, a professor of nutrition at the University of Alberta, suggests that one of the reasons for the confusion is that a food intolerance can sometimes cause the same response as a food allergy, even though food intolerances “aren’t true allergies.”

Dr. Field notes that the symptoms of a food allergy or intolerance can happen within minutes or may take a number of days to appear. 

She also notes that when the onset of symptoms is delayed, it’s harder to figure out what is causing the symptoms.

Allergy testing can help to clarify what is going on and it is important to seek medical advice rather than resorting to self-diagnosis and self-treatment.

Facts of the Matter
Despite what we sometimes hear, true food allergies are relatively uncommon. 

Heath Canada estimates that food allergies affect three to four percent of adults and about six percent of young children (between the ages of one and five).

Dr. Field notes that most allergies develop early in life. She recommends that parents follow guidelines for the introduction of solid foods and look for symptoms of an allergic reaction when introducing babies to unfamiliar or first foods.

She adds, “Babies can have allergies to something new in their diets if their immune systems aren’t ready to develop a tolerance. That tolerance is something the immune system learns in the first year of life.”

Sometimes people develop food allergies later in life, but this happens rarely, explains Dr. Field.

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Allergic Reactions to Foods
All foods have the potential to cause an allergic reaction. However, in reality, only a fairly small number of foods account for more than 90% of reactions.  Among adults, such foods include peanuts, nuts, fish, and shellfish. Among children, they include eggs, milk, peanuts, soy, and wheat.

Allergic reactions may include any of the following symptoms:

• trouble breathing, speaking or swallowing
• a drop in blood pressure, rapid heartbeat, and/or loss of consciousness
• flushed face, hives or a rash, or red and itchy skin
• swelling of the eyes, face, lips, throat, and tongue
• anxiety, faintness, paleness, sense of weakness
• cramps, diarrhea or vomiting

For people with severe food allergies, eating even a small amount of a problem food or ingredient can trigger a serious allergic reaction.

If you have a food intolerance, you can probably eat small amounts of the food without having a reaction.

Because food intolerances do not involve the immune system, the symptoms of a food intolerance are often less extreme and more likely to involve complaints such as stomach upset, cramping or diarrhea. 

Proper Diagnosis
Wendy Busse, a registered dietitian from Red Deer, suggests that self-diagnosis of food allergies is “all too common” and can encourage unhealthy eating habits.

Some research has shown that self-diagnosis is unreliable, suggesting that while more than 30 percent of adults report having a food allergy, objective testing has shown that less than five percent have a true food allergy.

“What happens is that a person might start eliminating certain foods from their diets before being correctly diagnosed by an allergist,” explains Busse. “That can lead to them not getting the right amount of nutrients, vitamins and minerals in their diet.”

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If you are concerned that you may have a food allergy or intolerance, Busse recommends keeping a diary that tracks what you eat at each meal and any symptoms you experience afterwards.

You can then take the diary to your doctor who can use it to help with a diagnosis. The doctor can also make an appointment with an allergist who can perform the tests needed to diagnose a food allergy.

Maximize Your Healthy Eating Choices
Whether you have a food allergy or food intolerance, or not, it pays to focus on good nutrition.

Take steps to ensure you get a proper diagnosis of any food allergies or intolerances, and consult with your doctor about healthy eating choices and any foods you may need to avoid.

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Learn More
Calgary Allergy Network
Provides current, reliable information about allergies.

Food Allergy or Intolerance: What’s the Difference?
Information from the Dietitians of Canada.

Health Canada
Information on food allergies and intolerances.

Tips to Remember: Food Allergies
The American Academy of Allergy, Asthma and Immunology (AAAAI) offers practical tips from medical experts on the diagnosis and treatment of food allergies.