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Food Allergy or Sensitivity? (Part 1: Allergy)

Updated: Nov 8, 2023

In the world today, it's extremely common to have some type of physical reaction to food. A lot of time I hear people mention certain physical symptoms of discomfort and state that they have some type of food sensitivity. Some people wonder if they have food allergy if they haven't already been diagnosed. I want to demystify some of these details and break it down so that the long standing question of is it an allergy or sensitivity makes more sense.

Food Allergies

A food allergy is immune mediated. Essentially, your body feels threatened by a specific food and goes into hyperdrive to protect you from the harmful foreign invader. The food isn't really harmful, but if you have a food allergy, your body sees it as harmful. Think of when you get a fever as a response to some type of harmful infection. You feel sick, your temperature rises. Maybe you vomit or you get chills and your whole body hurts. It's because our immune system is trying to keep us safe. So with a food, it's the same as a fever, except the food isn't a harmful virus.

So what happens from there? To first identify a food allergy, you have to notice a symptom related to a specific food or foods. A reaction will usually be rapid and "acute." Some common signs of allergic reaction to foods may be: rash, hives, itchiness, redness (especially around the mouth), throat swelling/closing shut, difficulty swallowing, difficulty breathing, runny nose, coughing, vomiting/diarrhea, anaphylaxis. Needless to say, you'll know if you had an allergic reaction to food. One or more of these symptoms will pop up right away.

**Personal Experience** The first time that I noticed a reaction to a food, it was a kiwi. I was eight years old and I told my parents that I was choking on a kiwi seed. They didn't quite believe me, after all, a kiwi seed is extremely small. How could anyone choke on that?! The first noticeable reaction was quinoa of all things! I ate it for the first time when I was in high school. I had 3 bites and my body immediately rejected it via vomiting. I had it again shortly after thinking it was a fluke, and the same thing happened, 1-2 bites and I immediately got sick. A third time in my first year in college I made it a few bites and then, guess what? Same reaction. Needless to say, I stopped having it and years later my allergist told me that it was safe to assume that I was allergic to quinoa.

So how do you confirm if you have a food allergy? You have to get tested, though if you go into anaphylactic shock, you can assume that you have an allergy. There are 3 types of tests:

  1. Food Challenge- GOLD STANDARD. However, you HAVE to do this test in the safety of your doctor's office. The challenge is to consume the food with the suspected reaction and then see if you do in fact have the reaction. This test usually lasts about 2 hours, the window in which an allergic reaction to food would occur.

  2. Scratch Test- Pretty good. This is when your allergist will do some skin pricks, on either your back or forearm, placing proteins from many different foods to determine if you have a reaction. This allows for concentrated hives. If you have a reaction, the site of the skin prick will start to itch and then inflame. With a severe allergy, the reaction will swell and look like a giant hive on either your back or forearm. Ask for pictures if you do this test!

  3. IgE Blood Test- Pretty good as well. Let me emphasize: IgE, IgE, IgE. NOT IgG. IgE is indicative of an autoimmune response and allergic reaction (remember when I said that a food allergy is immune mediated). In this case, your doctor will take some blood samples and behind the scenes, expose the blood that you have provided to those different proteins from different foods. The blood test will come back with different ranges of results that indicate if you are in fact allergic to a food.

For assessing the scratch test and blood tests, I highly recommend listening to you doctor. I (a Registered Dietitian) can absolutely help you understand your results, read through them and provide insight, but I will always leave the final say up to your doctor. Ex. I may look at a result and see that you tested as mildly allergic to a food. In this case, I would call your doctor and ask if it was okay that you continue to consume a food that you are only mildly allergic to, especially if you never experienced symptoms, or if they wanted you to stay away from the food all together.


  1. A food allergy is an immune mediated reaction

  2. Presentation will be rapid onset and acute. The reaction will likely be severe.

  3. Symptoms to look out for: rash, hives, itchiness, redness (especially around the mouth), throat swelling/closing shut, difficulty swallowing, difficulty breathing, runny nose, coughing, vomiting/diarrhea, anaphylaxis.

  4. Testing strategies: 1. Food challenge in doctor's office 2. Scratch test with allergist 3. IgE Blood test

And of course, contact me if you have any further questions!


- Jody


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