| Dietary fibre supports gut health by feeding beneficial gut bacteria and providing fuel for fermentation. It also helps produce short-chain fatty acids that support the gut environment, adds bulk to stool and helps food move through the digestive tract. These and other benefits of fiber support a healthy and diverse gut microbiome. |
If you’ve had to deal with gut issues, you’ve likely received advice to increase your fibre intake. Fibre is one of the few parts of food that your body cannot fully digest. Instead, different types of fibre travel through your digestive tract, where some are fermented by gut microbes while others help add bulk to your stool.
But how does fiber support gut health?
What Is Dietary Fibre?
Dietary fibre is a type of carbohydrate found naturally in plant foods that the human digestive system cannot completely break down. Instead of being digested and absorbed in the small intestine like many other carbohydrates, fibre travels further down the digestive tract.
Your gut microbes can use certain types of fibre as food. Other types remain largely intact and help give stool its structure and bulk.
Fibre is found in foods such as vegetables, fruits, whole grains, beans, peas, lentils, nuts and seeds. Most plant foods contain a mixture of different fibres.
Soluble and Insoluble Fibre: What’s the Difference?
Soluble fibre dissolves in water and can form a gel-like substance. It is found in foods such as oats, beans, peas, apples, bananas and avocado.
Insoluble fibre does not dissolve in water. It adds bulk to stool and helps material move through the digestive tract. Whole grains, nuts and many vegetables provide insoluble fibre. Most plant foods contain both types.
How Fibre Supports Gut Health
How does fibre support gut health? Here are some key ways:
Fibre Feeds Your Gut Microbes
In a previous article on prebiotics vs probiotics, we learned that prebiotics provide food for certain beneficial microorganisms in the gut. When certain fibres reach the colon, gut microbes ferment them to get energy.
Different microbes can use different types of fibre. A diet containing beans, oats, vegetables, fruits, nuts and seeds provides a broader selection of food for gut microbiota than a diet built around only one or two sources of fibre.
Fermentation Produces Short-Chain Fatty Acids
So what happens when your gut microbes ferment fibre? They produce metabolites called short-chain fatty acids (SCFAs), including acetate, propionate and butyrate.
These compounds interact with the cells lining your colon and are involved in processes related to intestinal health, metabolism, immune function and inflammation. But not every fibre produces the same amount or type of SCFAs.
The type and structure of the fibre, the dose, the microbes present in your gut and individual differences between people can all influence the outcome. Research in humans has found that fibre can affect microbial activity and SCFA production, but the response isn’t identical for everyone.
So rather than asking, “Which dietary fibre is best?”, it makes more sense to ask, “How can I eat a variety of fibre-rich foods?”
Fibre Helps Keep Things Moving
As noted earlier, some types of fibre mainly help by adding bulk to stool and supporting its movement through the digestive tract. Insoluble fibre, in particular, helps increase stool bulk. So, as you increase your fibre intake, increasing fluids will help keep stool softer and easier to pass.
Which Foods Give You Fibre?
A varied diet can provide plenty of different fibres. Good sources include:
| Food group | Examples |
| Legumes | Beans, lentils, peas, chickpeas |
| Whole grains | Oats, millet, sorghum, whole-grain maize |
| Fruits | Apples, bananas, mangoes, passion fruit, avocado |
| Vegetables | Leafy greens, carrots, broccoli, pumpkin, sweet potatoes |
| Nuts and seeds | Groundnuts, peanuts, sunflower seeds, chia seeds |
Most importantly, mix it up. Different foods contain different types and structures of fibre, and your gut microbes are a diverse community with different nutritional preferences.
How Much Fibre Do You Need?
There isn’t one number that applies perfectly to every person. WHO recommends that adults consume at least 25 grams of naturally occurring dietary fibre per day, while recommendations from other authorities vary according to age, sex and energy needs.
Rather than obsessing over the number, start by looking at your plate. Are you eating vegetables regularly? Do you eat beans or other legumes? Are whole grains part of your meals? Do you eat fruit, nuts or seeds?
If the answer is “not often,” there’s probably room to increase your fibre intake.
How to Eat More Fibre Without the Bloating
Gas and bloating are common when fibre intake increases too quickly. Your microbes need time to adjust to having more fermentable material available.
Increase it gradually and drink enough fluids. You can add a little more beans to your meals, switch some refined grains for whole grains, add fruit to breakfast or include an extra serving of vegetables each day. And give your gut time to adapt.
Gut Feast Kenya makes gut-friendly eating enjoyable and practical. Our fermented vegetables include kimchi and different varieties of sauerkraut. You can also explore our Dr Kombucha range of fermented tea, which comes in four refreshing flavors.
Fibre Is Food for More Than Just You
Perhaps the most useful way to think about fibre is this: When you eat fibre, you’re feeding two systems at once, your body and the microbial community living in your gut.
Some fibre helps keep things moving. Some is fermented by gut microbiota. That fermentation produces compounds that interact with the gut and the wider body. And because different fibres behave differently, variety beats obsession with a single “superfood.”
Key Takeaways
- Fibre feeds your gut microbes. Certain fibres reach the colon and are fermented by gut bacteria.
- Fermentation creates useful compounds. Short-chain fatty acids such as acetate, propionate and butyrate are among the products of microbial fibre fermentation.
- Fibre also supports regular bowel movements. Less-fermentable fibres can add bulk to stool and help keep the digestive tract moving.
- Variety matters. Different plant foods provide different types and structures of fibre, so eating a range of fibre-rich foods gives your gut microbes more to work with.
Want to make fermented foods part of your gut-friendly routine? Explore Gut Feast Kenya’s fermented food and drinks including kombucha, kimchi and sauerkraut, and discover delicious ways to diversify your diet.
Frequently Asked Questions
How does fiber support gut health?
Fiber supports gut health by feeding gut microbes, helping produce short-chain fatty acids through fermentation and supporting normal bowel movements by adding bulk to stool.
What happens when gut bacteria eat fibre?
Certain gut bacteria ferment fibre that reaches the colon. This process produces metabolites, including short-chain fatty acids such as acetate, propionate and butyrate, which interact with the gut and other body systems.
Is soluble or insoluble fibre better for gut health?
Neither is “better.” Soluble and insoluble fibres have different properties and effects, and most plant foods contain a mixture of both. Eating a variety of fibre-rich foods gives you different types of fibre rather than relying on one category.
How can I prevent gas and bloating from eating fibre?
Increase your fibre intake gradually rather than making a sudden, dramatic change. Drink enough fluids and give your gut microbes time to adapt to the increased supply of fermentable fibre.
What foods are highest in fibre?
Beans, lentils, peas, whole grains, vegetables, fruits, nuts and seeds are all good sources. Including a mixture of these foods throughout the day is a practical way to increase your fibre intake.
Can I get enough fibre from food?
Yes. Fibre occurs naturally in many plant foods, including legumes, whole grains, fruits, vegetables, nuts and seeds. For most people, building meals around a variety of these foods is a practical way to increase fibre intake.