common allergens laid out across table in bowls

We hear about so many people these days who are either allergic to, have an intolerance to, or have a sensitivity to certain foods. You may know someone who has a peanut allergy or is gluten-free or follows a low FODMAP diet regimen. What does all of this mean? How do you decipher the difference? 

Food Allergy.

women holding her stomach in pain after consuming lactose productsA food allergy is an immune response to food in which the body identifies it as an invader that causes an allergic reaction. A common reaction is an Immunoglobulin E (IgE) mediated response that can produce symptoms such as hives, itchiness, swelling, throat tightness, and difficulty breathing. Eating even the smallest food particle, having cross-contamination, or inhaling it can lead to an anaphylactic reaction in some people. For this reason, people with food allergies are advised to carry an epi-pen for emergency situations. The top food allergens include peanuts, tree nuts, eggs, shellfish, fish, milk, wheat, and soy. Food allergy testing can be done through the blood to measure IgE antibodies or via skin-prick tests.  

Food Intolerance

Food intolerance is not an immune-mediated response, but rather a digestive issue such as the inability to process or digest a substance in a food. Examples of these might include lactose intolerance, in which a person lacks sufficient amounts of the enzyme lactase to break down lactose, or celiac disease, which is an autoimmune condition that inhibits the normal processing of gluten. People with food intolerances generally present with digestive symptoms such as gas, bloating, abdominal pain, diarrhea, or constipation. There are specific tests, such as blood tests, including IgA-tTG for celiac disease and a lactose tolerance test. Breath tests such as the hydrogen breath test can also be used for lactose intolerance, as can a stool acidity test. These tests can be helpful in assisting to diagnose certain food intolerances.

Food Insensitivity

meal plan check list used to keep track of foods being eatenA food sensitivity might include food or additive that the body does not tolerate well, but does not present as an IgE allergic reaction. These may include things such as non-celiac gluten sensitivity, caffeine, sulfites, dairy, food additives, etc. Like food intolerances, these symptoms often present as digestive issues, but may also cause skin conditions, migraines, ADHD, or other symptoms. There are food sensitivity tests available that measure Immunoglobulin G (IgG) antibodies which we can develop in response to certain foods, but it does not necessarily indicate a food sensitivity. The gold standard for identifying food sensitivities and intolerances is the use of an elimination diet, whereby the suspected foods are eliminated from the diet for ~2-6 weeks. This is then followed by a reintroduction challenge to identify any foods that bring about negative symptoms. Keeping a detailed food journal and symptom log can be very helpful in identifying any potential food sensitivities.  If definitive answers aren’t obtained through an elimination diet, testing might be indicated.


If you suspect you might have a food intolerance or sensitivity, you can work with one of the Registered Dietitians at Nutrition HealthWorks to determine if an elimination diet or testing might be best suited for you based on your symptoms and medical history.