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By Colleen D. Webb, MS, RDN, CLT

Living with IBD means dealing with a lot of gastrointestinal (GI) symptoms.  Fortunately, many of these symptoms can be managed with simple dietary changes.

Common IBD Symptoms

  • Diarrhea, sometimes bloody
  • Constipation
  • Abdominal pain / cramps
  • Urgency with bowel movements
  • Flatulence / gas
  • Bloating / abdominal distention
  • Tenesmus

Tenesmus is a constant and sometimes painful urge to pass stools without the ability to do so. Patients often report it being one of their most annoying symptoms.

I’ve worked with a lot of IBD patients who choose not to eat or drink before leaving their homes hoping to save themselves from rushing to the nearest bathroom or stifling painful gas, among other annoying outcomes.

Common IBD Food Triggers

Fatty Foods: Fatty and fried foods, such as cream-based soups, milkshakes, burgers and fries can worsen fecal urgency, abdominal pain, and diarrhea.  

While most people with IBD feel worse after eating fatty foods, those with overlapping small intestinal bacterial overgrowth (SIBO) or Crohn’s ileitis are at increased risk of fat malabsorption. Fat malabsorption leads to urgent loose floating stools, abdominal pain and bloating.

Animal fats, such as beef and dairy, cause more GI problems than plant fats, like olive oil or avocado.

Fibrous Foods: Fiber is an undigested carbohydrate. Certain forms of fiber can worsen abdominal pain, bloating and diarrhea. I like to refer to this form of fiber as roughage.

Roughage includes most raw vegetables, thick skins of fruits and vegetables (e.g. apple skin), seeds, nuts, and popcorn. Humans don’t break down roughage any more than we can chew it, so it travels throughout the GI tract pretty much intact. If you’ve seen undigested fruits and vegetables in the toilet, then you know what I mean!

People at risk for bowel obstructions, such as those with stricturing Crohn’s disease or scar tissue secondary to inflammation or prior GI surgeries, need to be extra cautious with roughage as it can get stuck in a narrowed GI tract.

Fortunately, you can enjoy fibrous foods by removing or breaking down the roughage before eating. Choosing soft fruits, such as avocados and bananas, smoothies, pureed soups, peeled vegetables and fruit, cooked vegetables and fruit, blended vegetable sauces, and nut butters are excellent ways to include nutritious high-fiber foods without the roughage.

Caffeine: Caffeinated foods and drinks, including coffee, black tea and chocolate, can stimulate bowel movements resulting in diarrhea.  

Besides causing loose stool and bowel urgency, caffeine can worsen gastroesophageal reflux (GERD) and heartburn.

Herbal teas or plain hot water with lemon are better for most people with IBD. However, note that any hot liquid can stimulate a bowel movement.


Sugar: Eating and drinking too much added sugar can cause a variety of GI symptoms, including nausea, diarrhea, gas, bloating and abdominal pain.  Plus, it leads to fatigue, chronic inflammation and an imbalance of gut bacteria. Yikes!

“Added sugar” includes sugars and syrups added to foods during processing, preparation or at the table.  Unlike naturally occurring sugars present in fruits, vegetables, milk and yogurt, added sugar offers zero nutritional benefit.

Sugar goes by many names, including agave, brown sugar, cane sugar, corn syrup, evaporated cane juice, fructose, high fructose corn syrup, honey, malt sugar, maple syrup, molasses, sucrose and more!

Beware of highly concentrated sweets, like cookies and candy, sugary drinks, such as soda, iced tea, lemonade, and sports drinks, and hidden sources of added sugar, including flavored yogurts, granola bars, and cereals.

Too often my hospitalized patients receive super sugary, high calorie, high protein supplements, such as Ensure and Boost, and sweet sports drinks, like Gatorade, and they end up with MORE diarrhea and GI discomfort.

To reduce your intake of added sugar, avoid soda, dilute juices and sports drinks with water, and try to keep your daily intake of added sugar to less than 30 grams per day.

Sugar Substitutes: That’s right, those little yellow, blue and pink packets aren’t any friendlier on the gut than sugar.  Research has linked artificial sweeteners to poor gut health and worsened GI symptoms, particularly diarrhea, abdominal pain, irregular bowel movements, intestinal gas, and bloating.

Avoiding artificial sweeteners isn’t as easy as forgoing the pastel sweetener packets.  You also have to check ingredient labels for: acesulfame potassium (also called acesulfame K and Ace-K), aspartame (Equal), saccharin (Sweet n’ low), sucralose (Splenda), neotame and advantame.

Keeping away from packaged foods labeled “light”, “sugar-free” or “diet” will help you avoid artificial sweeteners and more gut irritants, like sorbitol, xylitol and other sugar alcohols.

Alcohol: Including wine, beer, and liquor, alcohol aggravates the GI tract and compromises the immune system.

Alcohol can cause unwelcome GI distress for most people, but those with IBD suffer more.  People with IBD commonly report gas, bloating, heartburn, abdominal pain or diarrhea after drinking.

Fat malabsorption is to blame for the loose, floating stool commonly experienced the morning after a few drinks, particularly if you enjoyed your adult beverages with a fatty meal.

Lactose: Research suggests people with Crohn’s disease have a higher rate of lactose intolerance than the general population.

Lactose is the natural sugar found in milk, and those with a lactose intolerance experience gas, bloating, abdominal pain and/or diarrhea shortly after eating lactose-containing foods, like milk or ice cream.

The good news is that hard aged cheeses, like Swiss and cheddar, and plain yogurts are lower in lactose and usually tolerated by people with a lactose intolerance.

Wheat/gluten: People with an autoimmune disease, including IBD, sometimes report an intolerance to wheat or gluten, even if they do not have celiac disease.

Gluten is a protein found in wheat, rye and barley, and folks with non-celiac gluten sensitivity (NCGS) report a wide range of symptoms from eating gluten containing foods, including bloating, diarrhea, abdominal pain, indigestion, joint pains, anxiety and depression.

There is no reliable test for NCGS so most cases are self-diagnosed based on symptoms improving on a gluten-free diet.

In my experience, lots of people with IBD feel better without gluten.  For some, they likely can’t tolerate the gluten or other proteins in the wheat; for others, they can’t tolerate wheat’s gas-producing carbohydrates. Whatever the reason, there are lots of wheat-free grains to explore, including rice, wild rice, buckwheat, oats, and millet.

FODMAPs: A clumsy acronym for certain types of sugars and fibers that are poorly absorbed and highly fermentable. They frequently cause gas, bloating, diarrhea and abdominal pain in people with gut issues.

A few examples of high FODMAP foods include milk, wheat, apples, watermelon, dried fruit, sugar-free gum, onions, garlic, cauliflower and honey.

I have recommended a low FODMAP diet to countless IBD patients and have seen it significantly improve symptoms, notably gas and bloating, and quality of life when carried out properly and in the setting of a very healthy diet with a variety of mostly whole foods.

There are a lot of websites and other resources devoted to a low FODMAP diet, but the information is often inconsistent and always changing, so I encourage you to work with a knowledgeable Registered Dietitian before carrying out any sort of an elimination diet.

How To Identify Food Triggers

Keeping a thorough food, symptom and lifestyle diary can help you identify food triggers.

For tracking food intake, write everything you eat as soon as you’re finished eating and include the time.  Don’t wait until the end of the day to record your whole day’s worth of food. Record as many details as you can regarding portion sizes and ingredients.

For example, if you ate a sandwich for lunch then record everything in and on that sandwich.  There’s a big difference between writing “turkey sandwich at 2pm” and “3 ounces turkey, 2 slices avocado, 1 tbsp mayo, 1 slice lettuce, 1 slice tomato, on 2 slices whole wheat bread at 2pm.”

Include additional columns for timing and severity of symptoms and other lifestyle factors, such as stressful events, exercise and sleep.  It’s easy to blame food for GI symptoms, but there are lots of other lifestyle factors at play!

And, look for trends in your diary versus onetime episodes.  Symptoms can appear anywhere from a few minutes after meals to a few days later.

I won’t lie, interpreting food/symptom diaries can be super frustrating!  I highly encourage you to work with an IBD nutritionist who can help you interpret your findings and determine next steps to uncovering YOUR food triggers.

Your nutritionist might recommend a tried-and-true elimination diet. Think of an elimination diet as a learning diet. If your symptoms improve on the diet, then you’ll be able to challenge foods in a more predictable setting. She might also suggest you undergo food sensitivity testing followed by a personalized healing diet.

You’ve Identified Food Triggers. Now What?

Determining what foods are worsening your symptoms is an important step to controlling your IBD symptoms, but there’s more work to be done to feel better in the long-term.

In my experience, there is too much emphasis on avoiding foods with IBD. People keep eliminating foods from their diets until there is little left to eat.

Now, if sugar and greasy fried foods are the only foods that bother you then continuing to avoid them is a great idea since they’re highly inflammatory and not part of a healthy diet.

But, most times it’s the nutritious, gut-healing foods that worsen symptoms so the old advice to “just avoid whatever bothers you” will not cut it.

We need to figure out why these healthy foods bother you and take steps to address the reasons.

For instance, the roughage in raw fruits and vegetables frequently trigger unwanted GI symptoms for people with active IBD, but blending these raw fruits and vegetables into smoothies and soups break down the rough fiber making them easier to tolerate.

Some people avoid gas-producing vegetables, such as broccoli and cauliflower, because they feel uncomfortable after eating them.  OK, we need to consider why someone feels worse after eating cruciferous vegetables.  Do they have untreated SIBO?  If they treated the SIBO, could they add back these veggies?

It’s not enough to avoid foods, we need to figure out why!

Key Takeaways


  • Dietary changes can improve IBD symptoms.
  • Although food triggers vary among individuals with IBD, there are a few common ones to keep in mind.
  • Keeping a thorough food and symptom diary is an important step towards identifying personalized food triggers.
  • If your food triggers are key parts of a healthy diet then it’s important to figure out why these foods bother you and take steps to address the underlying problems.

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