Each individual with IBD is unique, so before increasing your fibre intake, there are a few considerations to keep in mind. Here is everything you need to know about the best types of fibre to incorporate into your diet if you have IBD, and which types are more likely to provoke GI symptoms.
Fibre is an important component of a healthy diet, but those living with inflammatory bowel disease (IBD) commonly avoid fibre-rich foods out of fear that they may worsen gastrointestinal (GI) symptoms. In recent years, however, research has demonstrated that fibre can actually help to lower inflammation, improve gut microbiome health, reduce risk for colorectal cancer, and even aid in IBD symptom management. That said, fibre comes in many different forms, some of which are especially beneficial for IBD, while others may be irritating.
What Is Fibre and Why Do People With IBD Often Avoid It?
Fibre is a type of carbohydrate that the body cannot digest, naturally found in fruit, vegetables, beans, legumes, nuts, seeds, and whole grains. It passes through our GI tract mostly intact, and plays a number of key roles in maintaining overall health.
On average, those with IBD consume less fibre than those without IBD, according to research published in the April 2021 Journal of the Academy of Nutrition and Dietetics. In fact, less than a quarter of those with IBD are estimated to meet national fibre recommendations per the aforementioned research.
Historically, low-fibre diets were widely recommended to those with IBD to limit mechanical irritation to the gut lining, per a paper published in the Lancet Gastroenterology and Hepatology in May 2019 which was based on anecdotal reports of patients who felt better after removing fibrous foods from their diets.
Why Fibre Is Important for Those With IBD
While fibrous foods like fresh fruit and vegetables may sound like a bad idea when your GI tract is inflamed, some fibre types found in certain plant foods are gentle on the gut and are unlikely to worsen irritation.
In fact, higher fibre intakes are actually associated with reduced IBD inflammation and higher remission rates, according to research published in June 2022 in the journal Biomedicines.
Additionally, those with IBD have a higher risk of colorectal cancer than the general population, and high fibre intake is thought to be preventive against colorectal cancer, per the Biomedicines research.
Further, a common characteristic among those with IBD is reduced diversity of gut microbes, and an increase in certain bacteria thought to be harmful. High-fibre diets encourage a more diverse and favourable composition of gut microbes, which is associated with improved health outcomes and lower inflammation levels as outlined in the Biomedicines research.
That said, before drastically increasing your fibre intake, it’s important to speak with your healthcare team to ensure it is safe for you to do so, especially if you have Crohn’s disease, a history of bowel obstruction, or if you recently had surgery for your IBD.
Types of Fibre That Are Beneficial for IBD
Soluble fibre is a gentle type of fibre that helps normalise bowel function. While most people associate fibre with the alleviation of constipation, soluble fibre can also improve diarrhoea. According to the Crohn’s & Colitis Foundation, it does this by soaking up water in the GI tract forming a gel. This gelling property slows the rate of food moving through the GI tract, allowing more time for the intestines to absorb water.
Some types of soluble fibre, like inulin or resistant starch, are fermentable by our gut bacteria, meaning they serve as their food, per research published in the journal Nutrients in November 2022. When our gut bacteria are properly nourished, they produce anti-inflammatory compounds called short-chain fatty acids. According to the Nutrients research, these compounds regulate our immune system, maintain a healthy gut lining, and protect against harmful bacteria. You can find soluble fibre in the fleshy part of fruit and vegetables, and in beans, legumes, nuts, seeds, and certain grains. Some examples of IBD-friendly foods rich in soluble fibre include oatmeal, rice, barley, polenta, potatoes without skin, squash cooked and peeled, smooth nut butters, hummus and bananas.
Types of Fibre That May Aggravate IBD Symptoms
Insoluble fibre does not hold onto water and is often referred to as “roughage.” It helps push food through the GI tract more quickly, resulting in a laxative effect, per the American Gastroenterological Association. Insoluble fibre tends to be less fermentable by our gut microbes than soluble fibre, so while it is still a healthy component of the diet, its main role is to provide bulk to stool rather than feeding good gut microbes. You can find insoluble fibre in bran, whole nuts and seeds, leafy greens, and the skins of fruit and vegetables, per Harvard T.H. Chan School of Public Health.
Those actively experiencing IBD symptoms often benefit from reducing their intake of insoluble fibre and replacing it with foods rich in soluble fibre instead.
The low FODMAP diet is an elimination diet used to identify dietary triggers in those with IBS. “FODMAP” is an acronym that stands for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols,” fancy terms for fibres that are highly fermentable by our gut bacteria. As a by-product of fermentation, gut bacteria produce gas and draw water into the intestines, triggering GI symptoms for some. Foods high in FODMAPs include legumes, wheat, lactose-containing dairy, and certain fruit and vegetables like onions, garlic, artichokes, mushrooms, cauliflower, apples, and peaches.
Everyone’s FODMAP tolerance is unique, so it’s helpful to work with a registered dietitian or qualified nutritionist to pinpoint which FODMAPs may trigger your symptoms specifically. It is also important to note that while avoiding FODMAPs can improve functional IBS-like symptoms for some, this does not necessarily equate to a reduction in GI inflammation. The low FODMAP diet has not been shown to reduce IBD inflammation, according to the Crohn’s & Colitis Foundation.
It is not advisable to start the low FODMAP diet without guidance from a registered dietitian or qualified nutritionist, as it is highly nuanced, and avoiding high FODMAP foods for a prolonged period can negatively impact the gut microbiome, according to research published in the journal Microorganisms in November 2020.
How to Increase Your Fibre Intake
When upping your fibre intake, it’s best to start “slow and low,” gradually increasing the amount and variety of fibre-rich foods you eat over time. This allows your GI tract and gut microbes to adjust. Increasing your fibre intake too quickly can lead to bloating, cramping, gas, and bowel irregularity. It is also helpful to lean toward soluble over insoluble fibre sources, which tend to be better tolerated during IBD flares, according to the Crohn’s & Colitis Foundation.
To increase the soluble to insoluble fibre ratio in your diet, try peeling skins off fruit and vegetables before eating or cooking them, and select foods that are soft in texture.
Modifying food textures by blending, pureeing, or mashing may also improve your tolerance of the fibre they contain.
Lastly, you’ll want to make sure you’re drinking plenty of water to help the fibre move through your GI tract smoothly.