Should I avoid fibre with my IBD?
One of the most controversial topics concerning diet and Inflammatory Bowel Disease is the role that fibre plays. When I was first diagnosed, the one piece of dietary advice I received was to avoid high fibre foods and to follow a low residue diet. Whilst following this advice may help to reduce some symptoms, it appears contradictory to current advice for gut health. With the advancements in microbiome research, it now appears what we eat and what we feed our gut microbes may play a crucial role in healing and preventing flares.
In this blog we take an in-depth look at the latest research on fibre and the microbiome and discuss why fibre is important for people with IBD.
What is fibre, and why do I need it?
It may surprise you to know that most fibre is actually a carbohydrate like sugar and starch. However, in contrast to simple carbohydrates that provide us with a good source of energy, fibre is mainly indigestible. There are many different types of fibre with different characteristics of viscosity, solubility and fermentability, and each of these characteristics determines its function in the gut.
Some commonly known terms for the different fibres in foods are:-
Soluble Fibre – found in oats, bananas, legumes, lentils, peas.
Function - absorbs water in the stomach and small intestine forming a gel that slows down digestion. This can keep blood sugar stable, help us to feel fuller for longer and may help reduce diarrhoea.
Insoluble Fibre – found in leafy greens, seeds, nuts, grains and vegetable skins.
Function - does not break down in the small intestine, and instead draws in water to the colon to add bulk to stool.
Resistant Starch – cooked and cooled potatoes, rice and oats are a good source.
Function – a soluble fibre which feeds certain bacteria who produce short chain fatty acids which are beneficial to our health.
Prebiotic Fibre – found in bananas, onions, garlic, oats and asparagus.
Function - a term used to describe soluble fibres which pass through our guts undigested and act as a good food source for our ‘good’ gut bacteria. Not all fibre is considered to be prebiotic, but all prebiotics are fibre.
Why may fibre be important for IBD?
The benefits of fibre for forming our stools and its impact on the speed at which food moves through our bowels has long been understood. New research has unveiled that fermentability of fibre has a powerful influence on our overall health. When we consume fibre, it passes along undigested to the colon where our bacteria then break it down. When the bacteria break down the fibre, they produce compounds which help to support our gut health and overall health.
For example, one type of bacteria (Faecalibacterium prausnitzii), produces enzymes that break down a type of fibre called inulin (found in garlic and onions). When they do so they produce a short chain fatty acid called butyrate, which is the main source of energy for the cells in the colon, helping to keep them healthy (1). This type of bacteria is known to be lower in people with IBD, which could be due to a lower fibre intake.
Butyrate, along with other short-chain fatty acids (SFCAs) such as acetate and propionate, are all by-products of the fermentation of fibre in the gut by certain bacteria. These SCFAs are thought to serve several crucial functions in gut health including acting on the immune system to keep it well balanced, reducing inflammation and supporting a healthy gut barrier (2).
People with IBD have been shown to have a lower diversity of bacteria in their guts (3), which means that we are likely to not be getting enough of the bi-products that they produce. It has been seen in studies that without fibre as a food source, some bacteria may turn to start consuming the mucus layer which protects the gut barrier. The mucus layer is known to be diminished in people with Crohn’s disease and ulcerative colitis (4). Having more of these fibre loving ‘good’ bacteria in our guts, is also thought to keep the numbers of ‘not so good’ (pathogenic) bacteria lower, these bacteria such as, E.coli., are present in higher numbers in people with IBD (5)
Some research has observed that people with IBD who restrict fibre longer term could be more likely to relapse (6). There is also emerging evidence that suggests higher fibre diets could be effective in IBD (7) and that some specific fibres could reduce relapses in UC (8).
So, why have I been told to avoid fibre?
Traditionally, it is recommended that people with IBD avoid all fibre to prevent further aggravating inflamed intestines, in favour of consuming food which is digested higher in the gut. Now, research is showing this practice may have a negative impact on long term gut health and the diversity of our microbiome. Additionally, improving overall gut health and functioning appears to be important in reducing inflammation and potentially flare-ups.
However, there may be good reasons to avoid insoluble fibre, such as the skin of fruit and vegetables, in Crohn’s disease if you have strictures (narrowing in the bowel), as the indigestible nature of this fibre could cause a blockage. This is why it is important to understand the different types of fibre, as it may not be necessary to restrict all fibre in this case.
Soluble fibres such as avocado, banana and well-cooked/blended oats, may be less likely to cause a blockage or aggravation of the intestines. Additionally, well cooked peeled and deseeded or blended/pureed fruit and vegetables such as apple sauce, carrots, broccoli, butternut squash, courgette, tomatoes and peppers are less likely to cause an obstruction or irritate the intestines (as long as they are otherwise well tolerated). However, its really important to follow the advice of your dietician or seek help before changing your diet if you have strictures.
How can I increase my fibre intake without making symptoms worse?
During active flares, it is still encouraged to stay away from the rough insoluble fibre found in fruit and vegetable peels, wholegrains, nuts and seeds, as these can exacerbate symptoms in some people. However, it is still possible to feed your good gut bacteria with the food they desire by changing the texture of fibrous foods to make smoothies, soups and purees, achieved by blending fruits, nuts, seeds and vegetables, which can help make them better tolerated.
In remission, unless you have a stricture there is no reason to restrict fibre but increasing fibre should be done slowly. If we haven't eaten fibre for a while, then suddenly we have lots, it can make us feel bloated or cause gas, so increasing it slowly allows our gut time to adjust and reduces the likelihood of symptoms. If you find you still experience symptoms like bloating, pain, diarrhoea or constipation in remission these can often be managed with dietary changes, so it’s really helpful to seek advice from a nutritionist or dietician to help guide you.
Takeaways
Not all fibre is the same.
Fibre is important for long term gut health.
Fibre intake should be increased gradually to avoid gastrointestinal discomfort.
Always seek professional advice form a nutritionist or Dietician when increasing your fibre or changing your diet.
The texture of fibre is important for tolerability, try blending fruit and vegetables and cooking well to break down the indigestible fibres during periods of flare which can help us tolerate them better.
Some studies have shown people with IBD who eat a diet high in fibre reduce flare-ups and have improved prognosis.
If you would like help and support with your IBD and what dietary and lifestyle changes would be appropriate for you, please get in touch with me. You can book a free call, where I can get to know you, your journey, your struggles, your life, and we can chat about the best route forward for you. You can also ask any questions you have about working with me.
This article was written by Helen Morris (MSc, ANutr) who is our wonderful intern at The NALM Clinic. She's passionate about IBD nutrition research and sharing evidence based IBD nutrition information having lived with Crohn's Disease since 2018.
References
Canani, R. B. (2011). Potential beneficial effects of butyrate in intestinal and extraintestinal diseases. World journal of gastroenterology, 17(12), 1519–1528. https://doi.org/10.3748/wjg.v17.i12.1519
Parada Venegas, D. (2019). Short Chain Fatty Acids (SCFAs)-Mediated Gut Epithelial and Immune Regulation and Its Relevance for Inflammatory Bowel Diseases. Front. Immunol. 10, 277
Nishida, A. (2018). Gut microbiota in the pathogenesis of inflammatory bowel disease. Clin J Gastroenterol. 2018 Feb;11(1):1-10. doi: 10.1007/s12328-017-0813-5. Epub Dec 29. PMID: 29285689.
Johansson ME (2014). Mucus layers in inflammatory bowel disease. Inflamm Bowel Dis. Nov;20(11):2124-31. doi: 10.1097/MIB.0000000000000117. PMID: 25025717.
Palmela C (2018). Adherent-invasive Escherichia coli in inflammatory bowel disease Gut 2018;67:574-587.
Brotherton C.S. (2016). Avoidance of fiber is associated with greater risk of crohn’s disease flare in a 6-month period. Clin Gastroenterol Hepatol. 2016 Aug;14(8):1130–6.
Chiba, M. (2010). Lifestyle-related disease in Crohn's disease: relapse prevention by a semi-vegetarian diet. World journal of gastroenterology, 16(20), 2484–2495.
Hallert, C (2003) Increasing Fecal Butyrate in Ulcerative Colitis Patients by Diet: Controlled Pilot Study, Inflammatory Bowel Diseases, Volume 9, Issue 2, 1 March 2003, Pages 116–121, https://doi.org/10.1097/00054725-200303000-00005