Back to Basics: Food Allergies and Intolerances

August 20, 2009 · Posted in Ask A Dietitian

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What is the difference between a food allergy and a food intolerance? This is a question we’ve been asked many times, so we’ve consulted with Vincci Tsui, a Registered Dietitian, for a response.

A food allergy is when a person’s immune system reacts to a specific protein in a certain type of food. Symptoms can range from mild, such as a rash or hives, itchy skin, abdominal pain, and swelling of the lips, face, tongue, or throat, to more serious reactions like nausea or vomiting, diarrhea, wheezing, nasal congestion, trouble breathing, and anaphylactic shock. Allergic reactions can be triggered even if just a small amount of the food is eaten, or in severe cases, if the food is present in the room. Health Canada estimates that 3-4% of the adult population have food allergies, while as many as 6% of young children have them. Figures from the Center for Disease Control and Prevention in the States are similar, estimating that food allergies affect 4-8% of children and 2% of adults.

A food intolerance is when the body is unable to digest or absorb certain foods, or components in the foods. It does not involve the immune system, and may be the result of other conditions in the digestive system, such as irritable bowel syndrome, Crohn’s disease, or ulcerative colitis. Food intolerances are generally not life threatening, and symptoms can include stomach pain or cramps, nausea or vomiting, diarrhea, gas or bloating, headaches, and irritability or nervousness. Food intolerances generally require larger portions to trigger a response; for example, someone who is intolerant to lactose (a sugar naturally found in milk and dairy products) may be able to have a small amount of milk in their coffee, but cannot drink a full glass of milk. Intolerances are much harder to track in the population as symptoms vary and there are no accurate markers that doctors can measure, but it is known that they are more common in adults than they are in children.

The term “food sensitivities” covers all adverse reactions to food, including allergies and intolerances.

About the Contributor: Vincci Tsui is a Registered Dietitian based in Calgary, Alberta, Canada. She obtained her Bachelor of Science in Nutritional Sciences from McGill University, where she also completed her dietetic internship, which included placements in Montreal, Calgary and Hong Kong. She is currently practicing in a collaborative care clinic where she meets with clients with a variety of health and nutrition issues, including food allergies and sensitivities.Vincci is as passionate about food as she is about healthy eating and nutrition, and she strives to provide solutions that are healthy, yet tasty and easy to incorporate into busy lifestyles.