Fibre, Gut Microbiota and Short Chain Fatty Acids: What is the Connection?

Researcher: Dishita Ghai 

Research Editor: Sahij Sidhu We have all heard that fibre is good for our health. But between instant noodles and late nights, it is a nutrient that is very easy to ignore until you understand what happens to fibre in the gut.

What is Fibre?

Dietary fibre is a type of carbohydrate that comes from plants (Mukhopadhya & Louis, 2025). Unlike most of the food we eat, which is digested and absorbed in the small intestine, fibre passes through the small intestine and ends up in the colon, or large intestine.

Fibre can be categorized as soluble or insoluble (Soliman, 2019). Soluble fibre, found in foods such as fruits, vegetables, and oats, absorbs water and slows digestion, which helps you feel fuller for longer. Insoluble fibre, found in whole grains, seeds, and nuts, passes through the digestive system mostly unchanged and helps food move through the gut more quickly.

Fibre has several health benefits, including protection against cardiovascular disease, inflammatory bowel syndrome, obesity, type II diabetes, and colorectal cancer (Soliman, 2019). 

Figure 1

Dietary Fibre Sources

Examples of dietary fibre are whole grains, fruits, and vegetables. Image from Canva. 

Connection Between Fibre and the Gut Microbiome 

Our bodies are home to trillions of tiny organisms, with the largest group living in the gut (Vourakis et al., 2021). These organisms are known as the gut microbiota. The gut microbiota is constantly changing and can be influenced by factors such as diet, stress, medications, and the gut environment.

One of the main ways the gut microbiota affects our health is by producing short-chain fatty acids, or SCFAs (Mukhopadhya & Louis, 2025). These molecules are created when the gut microbiota ferments fibre, mostly in the colon. Different types of gut bacteria produce different SCFAs.

Soluble dietary fibre is first broken down into polysaccharides an

d oligosaccharides, which are complex carbohydrates (Mukhopadhya & Louis, 2025; Davidson, 2025). These complex carbs are then further broken down into their simplest form, called monosaccharides. Finally, these sugar molecules are fermented into compounds like pyruvate, acetate, and butyrate, which together make up more than 90% of the short-chain fatty acids in the gut.

Figure 2

Fermentation of Dietary Fibre in the Gut

Dietary fibre is converted into short-chain fatty acids – acetate, butyrate, and propionate – by the gut microbiota. Adapted from Miya et al. (2023).

How do Short-chain Fatty Acids Affect Health?

Short-chain fatty acids play a wide range of roles in the body. While there is evidence linking SCFAs to numerous health benefits, more research is still needed to get a better picture of how they work.

• Energy

SCFAs are a source of energy for various cells (Mukhopadhya & Louis, 2025). Colonocytes, the cells that line the large intestine, especially prefer butyrate as their main fuel. Overall, SCFAs account for 5 to 10% of our energy needs.

• Intestinal Health

SCFAs play an important role in maintaining the gut barrier and protecting it from harm. Butyrate supports the production of mucus, which forms part of this protective barrier, and SCFAs are also involved in forming tight junctions between intestinal cells (Mukhopadhya & Louis, 2025; Mann et al., 2024). Moreover, high levels of SCFAs create gut conditions that limit the growth of harmful microbes while supporting beneficial ones (Vourakis et al., 2021).

• Immune Function

SCFAs contribute to immune health by promoting the development of immune cells such as T and B cells, which help protect the body from harmful substances (Xiong et al., 2022). They also help lower inflammation by encouraging the production of anti-inflammatory molecules while reducing pro-inflammatory ones.

• Brain and Cognitive Health

SCFAs are thought to support brain health by helping maintain the blood–brain barrier, influencing microglia, and supporting the development and function of brain cells (Mann et al., 2024). Studies have also linked lower SCFA levels to neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis, suggesting their potential beneficial role (Mukhopadhya and Louis, 2025; Mann et al., 2024).

• Cardiovascular Health

SCFAs can lower the rate of in-body cholesterol production, hence reducing cholesterol in the blood and arterial blockage (Xiong et al., 2022). And acetate, in particular, has been shown to help reduce high blood pressure. SCFAs may also support the repair of heart tissue following injury, such as after a heart attack or reduced blood flow.

What does this mean for us?

Fibre is an essential part of our diet and can benefit our health through SCFAs. Health Canada recommends 25 g per day for women and 38 g for men, but many of us don’t get enough (Health Canada, 2025). Eating a balanced diet and including fibre in your meals can help keep your gut and your body healthy.

Disclaimer: This blog is intended for informational and educational purposes only. It is not intended to provide medical, dietary, or nutritional advice. Consult a professional if needed. 

References

Davidson, E. A. (2026, January 23). Carbohydrate. Britannica. https://www.britannica.com/science/carbohydrate

Health Canada. (2025, July 11). Fibre. Government of Canada. https://www.canada.ca/en/health-canada/services/nutrients/fibre.html

Mann, E. R., Lam, Y. K., & Uhlig, H. H. (2024). Short-chain fatty acids: Linking diet, the microbiome and immunity. Nature Reviews Immunology, 24(8), 577–595. https://doi.org/10.1038/s41577-024-01014-8

Miya, T. V., Marima, R., Damane, B. P., Ledet, E. M., & Dlamini, Z. (2023). Dissecting microbiome-derived scfas in prostate cancer: Analyzing gut microbiota, racial disparities, and epigenetic mechanisms. Cancers, 15(16), 4086. https://doi.org/10.3390/cancers15164086

Mukhopadhya, I., & Louis, P. (2025). Gut microbiota-derived short-chain fatty acids and their role in human health and disease. Nature Reviews Microbiology, 23(10), 635–651. https://doi.org/10.1038/s41579-025-01183-w

Soliman, G. A. (2019). Dietary fiber, atherosclerosis, and cardiovascular disease. Nutrients, 11(5), 1155. https://doi.org/10.3390/nu11051155

Vourakis, M., Mayer, G., & Rousseau, G. (2021). The role of gut microbiota on cholesterol metabolism in atherosclerosis. International Journal of Molecular Sciences, 22(15), 8074. https://doi.org/10.3390/ijms22158074

Xiong, R.-G., Zhou, D.-D., Wu, S.-X., Huang, S.-Y., Saimaiti, A., Yang, Z.-J., Shang, A., Zhao, C.-N., Gan, R.-Y., & Li, H.-B. (2022). Health benefits and side effects of short-chain fatty acids. Foods, 11(18), 2863. https://doi.org/10.3390/foods11182863