why is fibre important? 9 benefits for your gut, microbiome, and health.

We’ve all heard the advice: eat more fibre. But what does that really mean, and why is it so important? Fibre isn’t just about avoiding constipation (although that’s a big plus), it plays a central role in many of the processes that shape our wellbeing.

Most UK adults are well short of the 30g a day that government guidance suggests. Average intake sits closer to 16g/day, and only around 3-4% of adults aged 19–64 meet the target. That gap matters. Fibre is one of the most powerful daily inputs to the gut microbiome.

Let’s walk through why fibre deserves a starring role on your plate.

What is Fibre?

Fibre is a type of carbohydrate that our bodies can’t fully digest. Instead of being broken down into sugar, fibre travels through the digestive system largely intact, feeding the trillions of microbes that live in our gut.

There are two main types of fibre:

Soluble fibre

Soluble fibre dissolves in water and forms a gel-like substance in the gut. It slows digestion, helps maintain blood sugar levels, and contributes to normal cholesterol levels. Sources include oats, apples, citrus fruits, beans, lentils and barley.

One well-studied soluble fibre is fructooligosaccharide (FOS), a short-chain fibre found naturally in foods like onions, garlic, bananas and chicory root. FOS is fermented efficiently by beneficial gut bacteria such as Bifidobacteria, making it one of the more extensively researched prebiotic fibres.

Insoluble fibre

Insoluble fibre does not dissolve in water. It adds bulk to stool and supports regular bowel movements. Sources include wholegrains, nuts, seeds, green beans, and the skins of fruits and vegetables.

Most plant foods contain a mixture of both types, which is why variety is key.

Why Does Fibre Matter for Your Gut?

Fibre matters because it feeds the gut microbiome which is a community of bacteria, fungi and other microbes that play a central role in digestion, immunity and broader health. Different fibres nourish different bacteria, so the more variety you eat, the more diverse and resilient your gut becomes.

When microbes ferment fibre, they release short-chain fatty acids (SCFAs), mainly acetate, propionate and butyrate. Acetate is usually produced in the greatest amount, followed by propionate and butyrate. Together, these SCFAs help fuel the gut lining, regulate metabolism, and maintain immune balance. They also act as messengers, travelling beyond the gut to influence systems across the body, including the brain.

Butyrate - fuel for the gut lining

Butyrate is the preferred fuel source for the cells lining the colon. It supports gut barrier strength, helps regulate local inflammation, and promotes mucus production. Some studies also suggest it may have antibacterial properties by disrupting the way harmful bacteria use nutrients.

Propionate - metabolic balance

Propionate travels from the gut to the liver, where it may help reduce cholesterol production and support lipid balance. Research also suggests it could play a role in limiting the processes that contribute to colorectal cell overgrowth.

Acetate - appetite and energy regulation

Acetate is the most abundant SCFA, and an important player in energy regulation. It influences the release of appetite-regulating hormones like GLP-1 and PYY, which help balance blood sugar and support satiety (the feeling of fullness).

What happens when fibre is low?

In studies with mice, researchers observed that when fibre intake was low, gut microbes ran out of their preferred fuel and began consuming the gut’s protective mucus layer instead which made the gut wall more vulnerable. Although this finding was demonstrated in mice, researchers believe similar mechanisms may occur in humans. 

9 Reasons to Eat More Fibre

1. Supports regularity

Fibre contributes to normal bowel function by increasing stool bulk and softening it, which helps stools pass more comfortably.

Read more on what’s really happening in your gut during constipation.

2. Helps you feel fuller

High-fibre foods promote satiety (the feeling of fullness) which can help with appetite control. SCFAs produced from fibre fermentation stimulate gut hormones like GLP-1 and PYY that signal fullness to the brain.

3. Helps maintain steady blood sugar

Soluble fibre slows the absorption of glucose, supporting steady energy release after meals and helping to maintain blood sugar levels.

4. Nourishes your gut microbiome

Fibre feeds beneficial bacteria, encouraging a more balanced and diverse gut community. Greater microbial diversity is one of the most consistent markers of a resilient gut.

5. Supports immune balance

A large proportion of the immune system is associated with the gut. By influencing gut bacteria and SCFA production, fibre helps maintain normal immune function.

6. Contributes to healthy cholesterol levels

Certain soluble fibres, particularly beta-glucans from oats and barley, help maintain healthy blood cholesterol levels. The European Food Safety Authority has concluded that 3g of oat beta-glucan a day contributes to maintaining normal blood cholesterol.

7. Supports digestive comfort

Adequate fibre intake can reduce occasional digestive discomfort, such as constipation. Increasing fibre gradually, alongside enough fluid, helps the gut adjust without bloating.

8. Supports long-term colonic health

Fibre helps keep the gut environment healthy and supports normal colonic function. There is convincing evidence that diets rich in fibre, particularly from wholegrains, are associated with better long-term colonic health

9. Contributes to long-term wellbeing

A diet rich in fibre is linked with balanced energy, better overall dietary quality, and improved long-term health outcomes. Eating plenty of fibre is associated with a lower risk of heart disease, stroke and type 2 diabetes.

Why Does Fibre Matter More for Women?

Fibre plays a central role in hormone health because the gut and the hormonal system are biologically linked. The gut microbiome includes a group of bacteria called the estrobolome, that helps process and recycle oestrogen. Fibre is one of the inputs that shapes this bacterial community, helping to support healthy oestrogen metabolism over time.

Fibre during perimenopause and menopause

Gut microbial diversity tends to fall during the menopausal transition, and beneficial bacteria such as Lactobacillus and Bifidobacterium often decline. Diets rich in fibre and polyphenols may help support a more stable microbial environment during this stage of life.

How Much Fibre Do You Need Each Day?

UK government guidance suggests adults aim for around 30g of fibre per day. Most of us are some way off, the National Diet and Nutrition Survey found average intake among UK adults aged 19–64 sits at about 16g, with only 4% meeting the recommended target.

How to Eat More Fibre Without Discomfort

Fibre is best added through a variety of whole plant foods like fruits, vegetables, pulses, nuts, seeds and whole grains, combining soluble and insoluble fibres.

Useful daily habits include:

• Choosing wholegrain versions of bread, pasta and rice

• Adding pulses (lentils, beans, chickpeas) to soups, stews and salads

• Snacking on nuts, seeds and fresh fruit with skins on

• Aiming for around 30 different plant foods across the week - this includes herbs, spices, nuts and seeds, not just fruit and veg

Even modest increases can make a measurable difference. 

Why Pairing Fibre with a Synbiotic Can Help

You’ve probably heard of probiotics (beneficial bacteria) and prebiotics (fibres that feed them). A synbiotic combines the two so they can work together to support gut health.

Here’s why that matters:

• Nutrient absorption - a healthy gut environment helps ensure vitamins and minerals from your food are absorbed effectively

• Immune support - a balanced microbiome plays an important role in maintaining normal immune function

• Metabolic balance - through compounds like SCFAs, gut bacteria influence processes linked to digestion and metabolism

Our daily synbiotic duo cap is formulated with FOS as its prebiotic fibre source, designed to support microbial balance, gut barrier strength and digestive signals. As part of a varied plant-rich diet, a daily synbiotic may help support the gut system day to day.

Movement is another important part of the picture, read more on why exercise matters for gut health.

References

Baker, J. M., Al-Nakkash, L., & Herbst-Kralovetz, M. M. (2017). Estrogen–gut microbiome axis: Physiological and clinical implications. Maturitas, 103, 45–53. https://doi.org/10.1016/j.maturitas.2017.06.025

Byrne, C. S., Chambers, E. S., Morrison, D. J., & Frost, G. (2015). The role of short chain fatty acids in appetite regulation and energy homeostasis. International Journal of Obesity, 39(9), 1331–1338. https://doi.org/10.1038/ijo.2015.84

Desai, M. S., Seekatz, A. M., Koropatkin, N. M., Kamada, N., Hickey, C. A., Wolter, M., Pudlo, N. A., Kitamoto, S., Terrapon, N., Muller, A., Young, V. B., Henrissat, B., Wilmes, P., Stappenbeck, T. S., Núñez, G., & Martens, E. C. (2016). A dietary fiber-deprived gut microbiota degrades the colonic mucus barrier and enhances pathogen susceptibility. Cell, 167(5), 1339–1353.e21. https://doi.org/10.1016/j.cell.2016.10.043

EFSA Panel on Dietetic Products, Nutrition and Allergies. (2011). Scientific opinion on the substantiation of health claims related to beta-glucans from oats and barley and maintenance of normal blood LDL-cholesterol concentrations. EFSA Journal, 9(6), 2207. https://doi.org/10.2903/j.efsa.2011.2207

Facchin, S., Bertin, L., Bonazzi, E., Lorenzon, G., De Barba, C., Barberio, B., Zingone, F., Maniero, D., Scarpa, M., Ruffolo, C., Angriman, I., & Savarino, E. V. (2024). Short-chain fatty acids and human health: From metabolic pathways to current therapeutic implications. Life, 14(5), 559. https://doi.org/10.3390/life14050559

Holmberg, S. M., Feeney, R. H., Prasoodanan, V. P. K., Puértolas-Balint, F., Singh, D. K., Wongkuna, S., Zandbergen, L., Hauner, H., Brandl, B., Nieminen, A. I., Skurk, T., & Schroeder, B. O. (2024). The gut commensal Blautia maintains colonic mucus function under low-fiber consumption through secretion of short-chain fatty acids. Nature Communications, 15, 3502. https://doi.org/10.1038/s41467-024-47594-w

Mahalak, K. K., Firrman, J., Narrowe, A. B., Hu, W., Jones, S. M., Bittinger, K., Moustafa, A. M., & Liu, L. (2022). Fructooligosaccharides (FOS) differentially modifies the in vitro gut microbiota in an age-dependent manner. Frontiers in Nutrition, 9, 1058910. https://doi.org/10.3389/fnut.2022.1058910

McDonald, D., Hyde, E., Debelius, J. W., Morton, J. T., Gonzalez, A., Ackermann, G., Aksenov, A. A., Behsaz, B., Brennan, C., Chen, Y., DeRight Goldasich, L., Dorrestein, P. C., Dunn, R. R., Fahimipour, A. K., Gaffney, J., Gilbert, J. A., Gogul, G., Green, J. L., Hugenholtz, P., … Knight, R. (2018). American Gut: An open platform for citizen science microbiome research. mSystems, 3(3), e00031-18. https://doi.org/10.1128/mSystems.00031-18

NHS. (2022). How to get more fibre into your diet. National Health Service. Retrieved May 2026, from https://www.nhs.uk/live-well/eat-well/digestive-health/how-to-get-more-fibre-into-your-diet/

Office for Health Improvement and Disparities. (2025). National Diet and Nutrition Survey 2019 to 2023: report. GOV.UK. Retrieved August 2026, from https://www.gov.uk/government/statistics/national-diet-and-nutrition-survey-2019-to-2023/national-diet-and-nutrition-survey-2019-to-2023-report

Peters, B. A., Lin, J., Qi, Q., Usyk, M., Isasi, C. R., Mossavar-Rahmani, Y., Vásquez, P. M., Daviglus, M. L., Cai, J., Wang, T., Thyagarajan, B., Burk, R. D., Knight, R., Kaplan, R. C., & Burk, R. D. (2022). Menopause is associated with an altered gut microbiome and estrobolome, with implications for adverse cardiometabolic risk in the Hispanic Community Health Study/Study of Latinos. mSystems, 7(3), e00273-22. https://doi.org/10.1128/msystems.00273-22

Public Health England. (2020). NDNS: Results from years 9 to 11 (combined) - statistical summary. GOV.UK. https://www.gov.uk/government/statistics/ndns-results-from-years-9-to-11-2016-to-2017-and-2018-to-2019/ndns-results-from-years-9-to-11-combined-statistical-summary

Singh, P., Gupta, S. K., Kundu, A., Grover, M., & Saha, S. (2024). Role of fructooligosaccharides in promoting beneficial gut bacteria: A prebiotic perspective. Food Bioscience. https://doi.org/10.1016/j.fbio.2024.105543

Vinelli, V., Biscotti, P., Martini, D., Del Bo’, C., Marino, M., Meroño, T., Nikoloudaki, O., Calabrese, F. M., Turroni, S., Taverniti, V., Unión Caballero, A., Andrés-Lacueva, C., Porrini, M., Gobbetti, M., De Angelis, M., Brigidi, P., Pinart, M., Nimptsch, K., Guglielmetti, S., & Riso, P. (2022). Effects of dietary fibers on short-chain fatty acids and gut microbiota composition in healthy adults: A systematic review. Nutrients, 14(13), 2559. https://doi.org/10.3390/nu14132559

World Cancer Research Fund / American Institute for Cancer Research. (2018). Diet, nutrition, physical activity and colorectal cancer. Continuous Update Project Expert Report. https://www.wcrf.org/wp-content/uploads/2024/10/Colorectal-cancer-report.pdf

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