- Fiber is a non-digestible carbohydrate that supports gut health and healthy bowel movements.
- Some types of fiber may make IBS symptoms worse—soluble fiber is generally better.
- Everyone with IBS tolerates fiber-rich foods differently and has different trigger foods.
Irritable bowel syndrome, or IBS, is a chronic gastrointestinal disorder impacting approximately 5% to 10% of Americans. Due to the complex nature of IBS, no two experiences are the same. Symptoms of IBS can involve constipation or diarrhea or a mix of both, bloating and/or digestive/abdominal pain, as well as anxiety and depression. Because IBS symptoms can change daily and are impacted by more than just what you eat, you may find it challenging to identify triggering and well-tolerated foods.
Fiber is a nutrient widely recommended for supporting the health of your gut and digestive tract. However, if you are managing IBS, you may find that consuming fiber can intensify gas, bloating or cramping. It’s essential to understand which type of fiber works well for your body and include it in a way that supports your health rather than making your symptoms worse. Here, we break down what people with IBS need to know regarding fiber, including insight from dietitians.
What Is Fiber?
Fiber, a type of carbohydrate that the body can’t fully digest or absorb, is naturally found in many plant-based foods. Fiber stays whole as it moves through your digestive tract, supporting gut health, keeping your bowel movements regular, and improving your gut microbiome. Foods rich in fiber include fruits, vegetables, whole grains, beans, nuts and seeds.
There are two types of fiber, soluble and insoluble fiber. Soluble fiber dissolves in water and forms a gel-like texture in the digestive tract. This type of fiber slows down digestion, promotes regular bowel movements and feeds the good bacteria in your gut. Food sources of soluble fiber include avocados, psyllium, chia seeds, flaxseed, apples and beans. Insoluble fiber, on the other hand, does not dissolve in water and adds bulk to your stools, helping move them through your digestive tract.
If you have IBS, the type of fiber you eat may be more important than the quantity. According to clinical guidelines, soluble fiber is usually better tolerated by those with IBS and may even lessen symptoms. Insoluble fiber, on the other hand, depending on the quantity, can make symptoms such as gas, cramping and bloating worse.
Benefits of Fiber for IBS
While eating more fiber may feel like a double-edged sword if you are dealing with IBS, here are a few ways fiber can be beneficial to your body.
Promotes Regular, Comfortable Bowel Movements
Soluble fiber, such as psyllium husk, may help you have a more predictable and well-formed bowel movement. A meta-analysis of fiber in those with chronic constipation found that people who consumed more than 10 grams of fiber daily over at least four weeks improved stool frequency and consistency. For those who experience constipation with IBS, this can result in less straining and stools that are easier to pass and more comfortable and consistent.
Reduces Overall IBS Symptoms
Danielle Smiley, RDN, LDN, CD-N, a registered dietitian, explains, “The right fiber helps stabilize the gut, keep inflammation in check and regulate bowels.” Consuming soluble fiber can improve abdominal tension, spasms and gas if you are managing IBS.
Feeds the Gut Microbiome
Many soluble fibers act as prebiotics, feeding certain gut bacteria. “Eating prebiotic fiber feeds the good guys in the gut, which helps to strengthen the integrity of the gastrointestinal tract, including the lining of the gut,” says registered dietitian nutritionist Sue-Ellen Anderson-Haynes, M.S., RDN, CDCES. Getting fiber from a variety of sources will deliver prebiotics to your gut.
Supports Overall Health
While IBS symptom relief may be the primary concern, eating enough soluble fiber can improve cholesterol and blood sugar levels and even help with weight management. Soluble fiber has been associated with reduced cholesterol and regulated blood sugar levels. Managing IBS long-term means finding fiber sources you can tolerate for digestive comfort and whole-body health.
Potential Drawbacks of Fiber for IBS
Insoluble Fiber May Worsen IBS Symptoms
Studies have shown that insoluble fiber does not significantly improve IBS symptoms and may worsen abdominal pain, bloating or bowel urgency in IBS, especially if you are managing IBS with diarrhea. Because insoluble fiber speeds up transit through the digestive system, if you are experiencing diarrhea-predominant IBS, you may notice an increase in your stool frequency and cramping if you consume too much, and reducing the amount of insoluble fiber you consume can be beneficial.
Sudden Large Increases in Fiber Intake Can Backfire
Although consuming more fiber is beneficial for most people, rapid increases can be detrimental for those managing IBS. For most adults, the recommended daily intake of fiber is about 25 grams for women and 38 grams for men, approximately 14 grams per 1,000 calories consumed. “One-third of patients will feel worse if they add fiber too quickly or in excessive amounts,” says gastroenterologist Aja McCutchen, M.D. She adds that the best outcomes come from individualized nutrition therapy for fiber and IBS management.
Fiber-Rich Foods Can Be High in FODMAPs
If you suffer from IBS, consuming fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) can increase your fermentable load, making your symptoms worse. Dietitians say that it is important to understand how FOMAPs can impact your body. “If your stomach is sensitive to certain fruits, vegetables, beans or whole grains, you may need to adjust the serving size of those foods so you can include them in your diet while minimizing digestive issues,” says registered dietitian Sadie Hitsky, M.S., RD.
Ashley Berthoumieux, M.S., RD, CDN, LDN, says, “Following a low-FODMAP diet is typically recommended for IBS to identify specific food triggers and manage symptoms. Low-FODMAP foods contain minimal amounts of certain carbohydrates that can trigger IBS symptoms like gas, bloating and pain.
Best Fiber Foods for IBS
Knowing the right type of fiber to consume is essential with IBS. Below are some of the best-tolerated fiber sources for people with IBS. The fruits and legumes are lower in FODMAPs, and cooking the vegetables helps soften them and make them a bit easier to digest.
Soluble fibers
Psyllium, oats, chia seeds, flaxseed, barley
Fruits
Kiwi, oranges, blueberries, strawberries, bananas
Legumes
Canned lentils, canned chickpeas, firm tofu
Vegetables (cooked)
Zucchini, carrots, green beans, spinach, eggplant
Other Tips for Getting Enough Fiber with IBS
- Work with your health care provider: Working with a team of providers that includes registered dietitians can be essential. There may be signs and symptoms that require seeing a medical doctor. “If there are symptoms that persist, or red flags such as unintentional weight loss, bleeding, severe or nighttime pain appear, the patient should be evaluated by a gastroenterologist” says McCutchen.
- Focus on color, type of fiber and variety: “I recommend layering fiber in each meal and throughout the day, such as a small serving of chia seed pudding or oatmeal at breakfast to start,” says registered dietitian Katrice Mayo, M.S., RDN, CLT. Then add a colorful lunch and dinner with whole grains. In addition to eating a variety of fiber-rich foods throughout the day, Mayo adds, “The best thing is to listen to your body and keep a food journal to get an understanding of triggering foods.”
- Watch those portions: Many fruits, vegetables and grains are low in fermentable fiber in smaller portions, but even low-FODMAP foods can become high-FODMAP in larger amounts, says Berthoumieux. This is why you often find you can tolerate a wheat cracker, for example, but not a whole sandwich. It’s not always the food itself but the total fermentable load.
- Add fiber to your favorite dishes: Consuming more fiber does not necessarily mean you need to change your diet completely. Small add-ins to the foods you are already eating can go a long way. “Add seeds in smoothies, overnight oats or even as fillers in plant-based meatballs!” recommends Anderson-Haynes. These minor tweaks can help you add more fiber without getting overwhelmed.
- Pair fiber with plenty of fluids: Fiber, whether soluble or insoluble, needs water to push through your digestive tract. Not consuming enough water can worsen the symptoms of IBS even when fiber intake is adequate.
- Be consistent, not perfect: With IBS, your digestive system thrives on routine. Making significant changes can be overwhelming to your digestive tract and increase your risks of symptoms. Consuming the same amount of fiber every day will be easier on your gut than alternating between low- and high-fiber days. Consistency and steadiness wins the race here.
Our Expert Take
Fiber can be beneficial to your gut and overall health, especially if you have IBS. The key is choosing the right type of fiber and not being too quick to increase fiber in your diet. The research has shown us that soluble fiber is most beneficial with IBS, compared to insoluble fiber. Soluble fibers, such as the gel-forming type we find in psyllium husk, are best tolerated and can improve bowel movements, reduce digestive cramping and pain and support your gut microbiome, while consuming fermentable fibers or insoluble fiber may trigger gas, bloating and cramping for some. The most important thing to remember is that IBS treatment should be individualized. What works for you may not work for other people. Making a list of fibrous foods that you tolerate and incorporating them in small amounts throughout the day is the most reliable way to get the benefits of fiber without worsening symptoms.
Frequently Asked Questions
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Can fiber irritate IBS?
Yes, fiber can irritate IBS, especially insoluble fiber, but this is not the case for everyone managing IBS symptoms. It is important to understand what fiber-rich foods you tolerate the best and what foods you only tolerate moderately.
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Is it safe to take a fiber supplement if I have IBS?
Generally speaking, it’s safe to take a fiber supplement with IBS, but the type and amount consumed may differ from person to person when managing IBS. It’s always best to start with a small amount of fiber, even when supplementing, and increase as tolerated. For most people, fiber supplements should supplement, not replace, the fiber from the foods you eat.
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What is the best type of fiber to have with IBS?
With IBS, the best type of fiber to consume as part of a well-balanced diet is soluble fiber. You can find soluble fiber in most common plant-based foods such as oats, spinach, strawberries and zucchini.
