Ask the Allergist: Food Allergy v. Intolerance

In honor of Food Allergy Action Month, we're excited to kick off our Ask the Allergist series, focused on providing food allergy education to families. At Ready. Set. Food!, we’re committed to all aspects of food allergy education, so families can make informed decisions about their children’s nutrition.

What is a Food Intolerance?

Food intolerances are adverse health effects caused by foods. They do not involve the immune system. The term food intolerance is often used interchangeably with the term food sensitivity.


  • Reactions to food (from a food intolerance) can include:
    • Metabolic (lactose intolerance)
      • Inability to digest lactose, a prominent sugar found in milk->gas, bloating, diarrhea
    • Pharmacologic (caffeine)
      • Jitteriness, etc.
    • Toxic (scombroid poisoning)
      • Ingestion of fish with high histamine levels due to improper handling
    • Undefined mechanisms
      • Gluten intolerance

Food intolerances are rarely ever life-threatening, but allergic reactions, specifically from IgE-mediated food allergies, can be life-threatening.


To learn more about IgE-mediated food allergies, check out our “What Is A Food Allergy?” blog post.


Isolated respiratory (runny nose, asthma, chronic cough, etc.) or gastrointestinal symptoms (abdominal pain, bloating, gas) should prompt a reconsideration of the diagnosis of food allergy as they rarely, if at all, occur alone in IgE-mediated food allergy.


Gluten-Related Disorders


There is a spectrum of gluten-related disorders. There is no such thing as a “gluten allergy.” Learn more about gluten-related disorders from our Chief Allergist here.

Food Intolerance Testing


There is no validated test to diagnose a food intolerance or sensitivity. Eliminating the suspect food, monitoring for resolution of symptoms and then reintroducing the food is the only way to determine sensitivity to a food.


What You Should Know About “Food Sensitivity Tests”


Tests marketed as “Food Sensitivity Tests” measure IgG antibody, which is a normal response to a food. However, consumers should note that:


  • these tests have never been validated by any scientific evidence
  • in fact, higher levels of IgG4 to foods may actually be associated with tolerance
  • many national/international allergy groups have recommended against their use

A Recent Breakthrough in Food Allergen Introduction

Thankfully, recent landmark studies (LEAP, EAT, PETIT) have proven that exposing babies to food allergens early and often is vital. In addition, new medical guidelines from the American Academy of Pediatrics, the National Institutes of Health (NIH), and the American Academy of Allergy, Asthma, and Immunology (AAAAI) have been published supporting early and sustained allergen introduction.

Along with a team of leading allergy experts and parents, I helped develop Ready. Set. Food!, a gentle, guided system based on these medical guidelines. After over a year of research and development, we're proud to offer Ready. Set. Food! to families like yours, making it as easy and safe as possible to introduce babies to peanut, egg, and milk in the amounts used in the landmark clinical studies.

Introduce Allergens Safely and Easily with Ready. Set. Food!

About the author:

Our Chief Allergist, Katie Marks-Cogan, M.D., is board certified in Allergy/Immunology and Internal Medicine, and treats both pediatric and adult patients. Originally from Cleveland, Ohio, she received her M.D. with honors from the University of Maryland School of Medicine. She then completed her residency in Internal Medicine at Northwestern and fellowship in Allergy/Immunology at the prestigious University of Pennsylvania and Children's Hospital of Pennsylvania (CHOP). After finishing training, she moved to Southern California and currently works in private practice. She is a member of the scientific advisory board for Ready. Set. Food! She currently resides in Los Angeles with her husband, 4-year-old son, and 1-year-old daughter where she enjoys hiking, building LEGO castles with her kids, and cooking with her family.

All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease.  If your infant has severe eczema, check with your infant’s healthcare provider before feeding foods containing ground peanuts.