Do You Have a Food Intolerance or Food Allergy?

People often use the terms “food intolerance” and “food allergy” interchangeably. The two, however, do not mean the same thing.

Not only do they have different definitions, their effects on the body require distinct solutions. Learn how to determine if you have a food intolerance or food allergy, and what is the best course of action for each one.   

What Is a Food Intolerance?

A food intolerance is more common than a food allergy. In fact, it’s estimated that 75 percent of the population experiences some sort of food intolerance, according to Wendy Myers, a functional diagnostic nutritionist and certified holistic health coach.

Food intolerances involve a digestive response whereas an allergy involves an immune response. Causes of food intolerances include the absence of digestive enzymes needed to fully digest a food, irritable bowel syndrome, food poisoning, sensitivity to food additives, recurring stress, and celiac disease, according to Dr. James T. C. Li, chair of the Division of Allergic Diseases in the Department of Internal Medicine at the Mayo Clinic. 

Lactose intolerance, the most common specific food intolerance, affects about 10 percent of Americans. Intolerances to soy, grain/gluten, corn, eggs, nuts, shellfish, preservatives, and artificial sugars and dyes are also common.

Symptoms of food intolerance may include one or more of the following:

  • Diarrhea
  • Gas, cramps or bloating
  • Headaches
  • Heartburn
  • Irritability or nervousness
  • Nausea or vomiting
  • Stomach pain

Although less severe than food allergies, intolerances can become more serious if not addressed. 

What Is a Food Allergy?

A food allergy is the result of the immune system targeting a food protein as a potential threat and attacking it. When this happens, your immune system produces abnormally large amounts of an antibody called immunoglobulin E (IgE) and these antibodies fight the food allergens—substances that cause an allergic reaction—by releasing histamine and other chemicals. These chemicals trigger symptoms of an allergic reaction. Bodily indications can range from mild to severe.

Mild symptoms may include one or more of the following:

  • Diarrhea
  • Eczema
  • Hives
  • Itchy mouth or ear canal
  • Nausea or vomiting
  • Nasal congestion or a runny nose
  • Odd taste in mouth
  • Redness of the skin or around the eyes
  • Slight, dry cough
  • Sneezing
  • Stomach pain
  • Uterine contractions

Severe symptoms may include one or more of the following:

  • Chest pain
  • Drop in blood pressure
  • Loss of consciousness
  • Shortness of breath or wheezing
  • Swelling of the lips, tongue, and/or throat
  • Trouble swallowing
  • Turning blue
  • Weak pulse

It’s estimated that up to 15 million people in the United States are affected by food allergies.

The most common food allergens are milk, eggs, wheat, soy, peanuts, certain stone fruits, and fish and shellfish.

How to Test for and Manage a Food Allergy

To help diagnose a food allergy, your health practitioner may recommend a temporary elimination diet in combination with skin or blood tests. Because some food allergies can cause symptoms similar to ones caused by food intolerances and sometimes the results of elimination diets can be inconclusive, your health practitioner may recommend what’s known as an oral food challenge (ORC).

An ORF is considered the gold standard for diagnosing allergies. Because this test could cause a serious reaction, a certified allergist must administer it at a facility where appropriate medications and medical equipment are available.

During an OFC, an allergist feeds you the suspect foods—or placebos—in measured doses that are gradually increased if no symptoms are triggered. If any reaction occurs, the OFC is stopped. 

There are three kinds of OFCs: double-blind, placebo-controlled (neither you nor the doctor know whether you’re receiving a potential allergen or a placebo); single-blind (only the allergist knows whether you’re receiving the potential allergen); and open-food (both you and the doctor know whether or not you’re receiving an allergen).

Once the allergen is identified, management usually involves food avoidance techniques and carrying an epinephrine auto-injector, which is used for injecting oneself with a measured dose of epinephrine (adrenaline). Use of one of these devices must be followed by immediate medical care.

How to Test for and Manage a Food Intolerance

If you think you may have a food intolerance, the best way to know for sure is to keep a detailed food journal in conjunction with doing an elimination or exclusion diet. Consult with your health practitioner before you try an elimination diet.

When doing an elimination diet, it’s recommended to wait at least 15 days before reintroducing the first suspect food, according to the Arizona Center for Integrative Medicine. When you start to reintroduce suspect foods, eat one at a time and allow at least three days to pass before reintroducing another potential problematic food. As you reintroduce the foods, take notes on how you feel after eating each one.

If you add back in all the eliminated foods and don’t experience any adverse effects, then remove new foods from your diet until you find the trigger. Once you’ve identified the trigger, avoided it for several months, and healed your gut, you may be able to tolerate it once again. Some people rotate in the once-problematic food every few days to see how it’s tolerated.

Learning to Live with Restrictions

If you learn that you have an allergy or intolerance to a certain food, avoiding or limiting that food may feel restrictive at first. Feeling better will eventually supersede the desire to eat that food.

Listen to your body, and find food alternatives that satisfy your nutritional needs and taste buds. If you eat out at a restaurant or at someone else’s home, don’t be shy about asking what ingredients are in the food. This will help reduce the risk of potentially eating a trigger food and will also help you feel more relaxed, so you can enjoy yourself in social settings. 

*Editor’s Note: The information in this article is intended for your educational use only; does not necessarily reflect the opinions of the Chopra Center's Mind-Body Medical Group; and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health providers with any questions you may have regarding a medical condition and before undertaking any diet, supplement, fitness, or other health program.

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About the Author

Nicole Leatherman

Nutrition Writer and Editor
Nicole believes in the Hippocratic philosophy, “Let food be thy medicine,” and her passion is creating content that helps others learn about self-healing through eating real foods and living an intentionally balanced life. When she isn’t writing or editing, she spends time in the yoga studio, on the mountain trails in Colorado, and in the kitchen creating recipes packed with nutrient-rich foods. She has a bachelor’s degree in journalism, and has been a professional writer and editor for more than 15 years.Read more