Food allergies and intolerances (and the relationship to IBD & IBS)

Traveling in Thailand, Spain, and even Italy (home of the glorious gluten foods), I was shocked to see “gluten-free” menu items everywhere. Airlines have stopped serving peanut packets and ask that you to keep nuts stowed away. Schools have implemented peanut-free zones, fading out the classic PB&J. Over the last 30 years, food allergies have rapidly increased. But before eliminating an entire food group in your diet, it’s important to ask, what’s the difference between an allergy and an intolerance?

What is a food allergy?

Your immune system has it’s very own personal military defense system. It’s a group of cells (white blood cells) that helps protect your body from infectious or harmful foreigners. If you have a true allergic reaction to food, your immune system responds by “tagging” the food in order to make it “visible”. Then anytime we eat it, your bodies sound the alarms, bringing attention to the troops to fight this foreign invader.

Allergies versus intolerances – what’s the difference?

Don’t be fooled by clever marketing ploys or expensive allergy tests. There’s a difference between an allergy, intolerance, and sensitivity.


A true food allergy only affects about 1-5% of the U.S. population and involves the immune system (as described above). Symptoms manifest quickly after exposure and can lead to a severe and life-threatening reaction called anaphylactic shock. Symptoms happen almost instantly after eating the food.

  • Standard symptoms: difficulty breathing, hives, swollen lips, tongue, or closing throat
  • Common culprits: eggs, peanut, tree nuts, milk, fish, shellfish, soy, wheat

If you experience any of these symptoms after eating, please contact an emergency medical provider immediately.


A food intolerance, means your body lacks or has limited amounts of an enzyme needed to break down certain carbohydrates in food (think milk sugar – lactose intolerance). You may be able to have small amounts of the food, but the more you have, the worse the symptoms get. Intolerances impact up to about 25% of Americans and reactions can change and fluctuate over your lifetime. Symptoms occur about one to four hours after eating.

  • Standard symptoms: gas, bloating, diarrhea, mucus, nausea, stomach pains
  • Common culprits: gluten (wheat), lactose (milk), fructose (fruit), soy


Sensitivities to food are seen in about 10-20% of the population. These tend to have a delayed reaction, a few hours to a few days after exposure. As you can imagine, this makes it very difficult to track down the culprit. Almost any food can cause a sensitivity and they can be related to leaky gut syndrome.

  • Standard symptoms: sinus pressure, skin irritation (rashes, itchiness, dry patches), gastrointestinal discomfort (gas, bloating, diarrhea, pain)
  • Common culprits: beef, egg, citrus, dairy, pork, wheat  

Relationship to IBD

The standard gut digests the majority of the food it’s given. However, barriers come into play with food allergies, food intolerances, IBD, and stomach flu. The gut lining becomes irritated and damaged, leading to less nutrient absorption.

It gets tricky. Certain foods can cause flare-ups, making symptoms worse, but diet and nutrition are one of the most important aspects of IBD management. According to the Crohn’s & Colitis Foundation of America, there’s no evidence to suggest that any particular food or diet causes, prevents, or cures IBD. Each of you are different and and deserve specific attention when it comes to what to eat.

To help narrow it down, the Crohn’s & colitis foundation partners research program, completed a survey of 4,001 patients with Crohn’s and 2,156 with ulcerative colitis. The survey displayed that these foods helped improve symptoms the most:

  • yogurt, white rice, bananas

While these made matters worse:

  • non-and leafy vegetables, spicy foods, fruits, nuts, fried foods, red meat, soda, popcorn, dairy, alcohol, high-fiber foods, corn, fatty foods, seeds, coffee, beans

Steps to identifying your allergies

Break it down into simple steps. First talk to your physician about the possibility of a true food allergy. Once you rule this out, start by keeping track of what you’re eating and how you’re feeling. Notice any links. For instance, when you have bread in the evening and a headache or bloating in the morning.  


Use Nori or a simple journal to help you discover and eliminate common allergens. Once you have an idea which ones are causing you gruff, eliminate them for at least two weeks then slowly reintroduce one back at a time and see how you feel. Otherwise known as an elimination diet that can be done with your physician or dietitian.

Tweak your meal

Once you identify foods that don’t serve you well, get creative about substituting them. There are hundreds of recipe options out there with many websites that allow you to search by allergen-free dishes. When you go out to eat, don’t be afraid to ask the server to modify your order. Let them know about your allergy or order things on the side, minimize sauces or seasonings, and go simple.

Gut health

Once you identify your food culprits, avoid them as best you can. It can be helpful to vary your diet for a variety of nutrients. Aim to support your gut in doing it’s best work to heal by limiting caffeine, alcohol, spicy foods, and aspirin or NSAIDs. Practice stress management techniques such as yoga or meditation and get a good night’s sleep as much as possible.  

Normalized eating

We know it can be very frustrating trying to uncover a food allergy, then learn how to live with it. We want you to feel your best, while enjoying social activities and the pleasure of eating. Food reactions can be quite confusing so let Nori Health help you play detective and discover the offenders. As always always reach out to your physician, dietitian, or allergist for guidance and education along the way.