The Low-FODMAP Diet for Crohn’s Disease

Life with Crohn’s disease can feel confusing: Tests may indicate that the chronic disease is under control, but you’re still struggling with digestive symptoms like bloating, gas, abdominal discomfort, or diarrhea.

These sugar molecules are poorly absorbed, so they move to the colon where they ferment, driving gas production and gut sensitivity, says Danielle Gaffen, RDN, a San Diego–based registered dietitian-nutritionist and the founder of Eat Well Crohn’s Colitis, which provides personalized nutrition counseling for people living with IBD and other digestive conditions.

• Bloating
• Abdominal pain and cramping
• Gas and flatulence
• Constipation
• Diarrhea

But reducing these carbohydrates temporarily, and then gradually reintroducing them, can help some patients pinpoint which foods may be triggering their symptoms, Gaffen says.

It’s an incredibly valuable tool for some Crohn’s disease patients, says Kristen Bentson, a nutrition specialist in Bethlehem, Pennsylvania, and the author of the Cool Girls’ Guide to the FODMAP Diet.

“I’ve helped many patients with IBD navigate this approach successfully. When combined with appropriate medical management and a functional approach — working on stress, sleep, movement, and correcting nutritional insufficiencies — it can truly transform quality of life,” Dr. Bentson says.

One of the most important things to understand about the low-FODMAP diet is what it can, and cannot, do for Crohn’s disease.

But people with Crohn’s can experience IBS at the same time, with symptoms that often overlap, Gaffen says. “Because the symptoms of Crohn’s disease and IBS can look very similar, it can be confusing for patients to know whether their symptoms are related to inflammation or gut sensitivity,” she says.

Gaffen recommends working with a healthcare team, including a registered dietitian and a gastroenterologist, to evaluate symptoms carefully. They’ll also use tools, such as fecal calprotectin tests, blood markers, or an endoscopy to check for inflammation in the intestinal tract.

If inflammation is active, the priority is bringing Crohn’s disease under control because diet alone won’t fix underlying tissue damage, Gaffen says. “The low-FODMAP diet is generally more appropriate when inflammation is well controlled, but patients continue to experience IBS-type symptoms,” she says.

Phase 1: Elimination

During the elimination phase, you temporarily remove foods high in FODMAPs from your diet. The goal is to calm digestive symptoms and create a baseline at which the gut is less reactive.

• Lactose-containing dairy
• Wheat and rye products
• Certain fruits such as apples and pears
• High-fructose corn syrup
• Vegetables like onions and garlic
• Legumes
• Sugar alcohol sweeteners including sorbitol and xylitol

This phase usually lasts between two and six weeks, depending on symptom improvement. “Many people begin to notice improvement in symptoms like bloating, gas, or abdominal discomfort within that timeframe,” Gaffen says.

Bentson says you may see a difference as early as the first week. If symptoms don’t improve over a few weeks, it may suggest that FODMAPs aren’t the trigger for your symptoms.

Phase 2: Reintroduction (the Challenge Phase)

Once symptoms improve, you gradually reintroduce foods from one FODMAP group at a time. This step helps identify which carbohydrates trigger symptoms for you. It usually takes about four weeks.

For example, you might test lactose for one week, fructose the next, and polyols afterward, while carefully monitoring for tolerance and the return of symptoms.

Bentson says this phase can feel intimidating because patients worry about triggering symptoms again. “That’s where dose-dependent intentional reintroduction strategies, guided by professional help, are key.”

Phase 3: Personalization

After identifying your triggers, the final stage focuses on building a long-term eating pattern that is as varied as possible while avoiding personal trigger foods.

You also need to watch for nutritional gaps. “When a food group is limited, it’s important to identify alternative foods that provide those nutrients so deficiencies don’t develop,” Gaffen says.

• Apples with the skin
• Some processed meats
• High-fiber legumes
• Processed baked goods
• Dairy products high in lactose
• Artificial sweeteners, especially sorbitol and mannitol

Processed foods can also contain hidden FODMAP ingredients such as chicory root, inulin, or high-fructose corn syrup, which may worsen symptoms for sensitive individuals, Gaffen says.

Because these ingredients often appear in unexpected places, such as protein bars, sauces, and packaged snacks, it’s helpful to read food labels carefully.

You should also pay attention to how food is prepared, Bentson says. “Chicken itself is low FODMAP, but not when it’s coated in a rub or sauce containing garlic and onion,” she says.

Although the low-FODMAP diet can help reduce symptoms, it also comes with potential downsides, especially if it’s followed too strictly or for too long.

It may also affect the bacterial diversity in your GI tract. “Prolonged restriction can negatively impact the microbiome, downregulate digestive enzymes, and reduce food tolerance over time,” Bentson says.

For that reason, both experts stress the importance of professional guidance to ensure you meet your nutritional needs and reintroduce foods safely. “Working with a dietitian experienced in the low-FODMAP diet can help ensure the diet remains nutritionally balanced,” Gaffen says.

If you’re exploring a low-FODMAP approach, small adjustments can make the transition easier. Bentson suggests these tips.

• Focus on variety — and a positive mindset. Rotating different low-FODMAP foods can help prevent boredom and ensure you’re getting a wide range of nutrients. Mindset matters, too. Focus on what you can eat rather than what you’re avoiding to make the diet feel more manageable. And remember: It’s a temporary phase, not a lifelong restriction.
• Use helpful apps. Tools like the Fig app or the Monash University FODMAP Diet app, which has a user-friendly red light/green light system, can help identify potential trigger ingredients while you’re grocery shopping.
• Use flavor-friendly swaps. Garlic- or onion-infused oils, asafoetida powder, and fresh herbs can add depth and savory flavor without the FODMAP load of whole garlic or onions. Cocoa powder is another low-FODMAP ingredient that can add flavor to foods like oatmeal or chia seed pudding.
• Watch for hidden FODMAPs. Ingredients like garlic powder, onion powder, and certain sweeteners can show up in sauces, spice blends, marinades, and packaged foods, so checking labels carefully is important.
• Be mindful with tea. Some teas, such as chamomile, oolong, and chai, may be higher in FODMAPs, while black, green, and white tea are generally better tolerated when brewed lightly. The more deeply steeped or strong, the higher FODMAP it becomes.
• Pay attention to portion size. Even low-FODMAP foods can trigger symptoms if you eat them in large quantities or combine them, so learning personal tolerance levels is key.

• The low-FODMAP diet can help reduce symptoms like bloating, gas, and abdominal discomfort in Crohn’s patients who are in disease remission but still encountering IBS-type symptoms.
• The diet works by temporarily reducing fermentable carbohydrates that can trigger gut sensitivity and gas production, helping patients identify their individual food triggers.
• Because the elimination phase is restrictive, this stage should only be followed short term — typically up to six weeks — before foods are gradually reintroduced one FODMAP group at a time to test for tolerance and symptom recurrence.
• Working with a registered dietitian or gastroenterologist can help avoid nutrition deficiencies while safely identifying symptom triggers and reintroducing foods.