Food Allergy and Food Intolerance: What’s the Difference?

A blonde woman standing in her kitchen with a glass of milk and her hand against her stomach, experiencing discomfort
Photo: ChesiireCat/iStock/Thinkstock

It is National Food Allergy Awareness Week, a great opportunity to educate those around us about the difference between food allergies and food intolerances. You would be surprised at how many people don’t know the difference between the two. Let’s jump into a little refresher, shall we?

What is the Difference Between a Food Allergy and Food Intolerance?

Food intolerance consists of some gastrointestinal upset that usually involves bloating, gas, diarrhea and sometimes cramping. The immune system is not involved in the response to food and the main issue is with digesting the food. A food allergy, on the other hand, can result in symptoms that range from very mild to severe and even as life-threatening as anaphylaxis, where there is swelling of the throat and tongue leading to difficulty breathing and a drop in blood pressure, or as mild as stomach pain, hives or eczema. Some food intolerances can involve the skin while some food allergies can also cause GI symptoms.

Testing for Food Allergies

According to Food Allergy Research & Education, the most accurate method for testing food allergies is a skin prick test, where a solution containing the food allergen is placed on the back or forearm and the allergen enters just underneath the skin. However, 50 to 60 percent of these tests give false positives and can show a person is more allergic than they actually are because of two reasons. First, when food is digested, it is broken down and the allergens may be so small that they might be undetectable, whereas with skin testing, the allergen is directly entering the bloodstream. Second, there is potential that a person will cross-react to another food because of similar proteins in two foods, such as peanuts and green beans.

Testing for food intolerance is more complicated because there is no immune system response evoked, as with food allergies. There is no evidenced-based testing method to identify most food intolerances. Food Allergy and Food Intolerance: What’s the Difference? - The most accurate way to sort out a food intolerance is to do an elimination diet under the supervision of a medical practitioner.

Beware the Gap!

Food avoidance for any reason can result in nutrient deficits and must be accounted for when altering the diet. Some nutrients may require careful monitoring and supplementation.

Rachel Bessire
Rachel Bessire is an MPH graduate from the University of Michigan and dietetic intern at Michigan Medicine in Ann Arbor.