Fibre is the part of plants you can't digest, which is exactly why it's useful: it bulks and softens stool, and it's what your gut bacteria live on. The targets are roughly 25 g a day for women and 38 g for men; most people manage about half. Add it slowly, drink more water, and get it from food rather than a capsule wherever you can.
If gut health had a single hero nutrient, it would be fibre. It's the foundation of good digestion, the primary food for your gut bacteria, and one of the most under-consumed nutrients in modern diets. Understanding fibre - and getting enough - does more for your gut than almost anything else. Here's a practical guide.
What Is Fibre, and Why Does It Matter?
Dietary fibre is the part of plant foods your body can't fully digest. Instead of being broken down and absorbed like other nutrients, it travels through your digestive system largely intact - and that's exactly what makes it so valuable. Along the way, it adds bulk to stool, feeds your gut bacteria, slows digestion in helpful ways, and supports overall digestive health. Despite its importance, most people fall well short of the recommended 25-38 grams a day.
The Two Types of Fibre (You Need Both)
Fibre comes in two main forms, and they do different jobs:
Soluble Fibre
Soluble fibre dissolves in water to form a gel-like substance. It slows digestion, helps soften stool, supports healthy cholesterol and blood sugar, and is a favourite food for beneficial bacteria. Find it in oats, beans, lentils, apples, citrus fruits, carrots, and psyllium.
Insoluble Fibre
Insoluble fibre doesn't dissolve in water. It adds bulk to stool and helps material move more quickly through the digestive tract, supporting regularity and helping prevent constipation. Find it in whole grains, wheat bran, nuts, and the skins of fruits and vegetables.
Most whole plant foods contain a mix of both types, which is why a varied, plant-rich diet naturally provides balanced fibre - no need to track them separately if you eat plenty of diverse plants.
How Fibre Supports Digestion and Gut Health
Fibre helps your gut in several interconnected ways:
- Supports regularity: it adds bulk and softness to stool, helping prevent constipation and supporting comfortable, regular bowel movements.
- Feeds your microbiome: your beneficial bacteria ferment soluble fibre, producing short-chain fatty acids (like butyrate) that nourish your colon lining and reduce inflammation.
- Promotes fullness: fibre slows digestion and helps you feel satisfied, supporting appetite control.
- Steadies blood sugar: soluble fibre slows the absorption of sugar, helping avoid spikes.
- Supports a healthy gut barrier: the compounds produced when bacteria ferment fibre help maintain the gut lining.
How Much Fibre Do You Need?
General guidance is around 25 grams a day for women and 38 grams for men (or roughly 14 grams per 1,000 calories). Many people get only half that. You don't need to count obsessively - instead, focus on building meals around plants: fill half your plate with vegetables, choose whole grains over refined, include legumes regularly, and snack on fruit, nuts and seeds. Do that consistently and you'll naturally approach a healthy fibre intake.
How to Increase Fibre Without Discomfort
A common mistake is increasing fibre too fast, which causes gas, bloating and discomfort as your gut adjusts. To avoid this:
- Increase gradually - add a little more fibre every few days rather than all at once.
- Drink plenty of water - fibre works with fluid; too little water can worsen constipation.
- Spread it across meals rather than loading it all into one.
- Stay active - movement helps fibre do its job in the gut.
- Be patient - initial gas usually settles as your microbiome adapts to the extra fibre.
Fibre vs Fibre Supplements (and Gut Supplements)
You can buy fibre supplements (like psyllium), and they have their place - particularly for specific needs like managing constipation. But whole-food fibre is generally superior because it comes packaged with vitamins, minerals, polyphenols and a variety of fibre types that a single supplement can't match. As for broad gut supplements like Gut Save, it's worth being clear: they contain only a tiny amount of fibre (in Gut Save's case, mainly from sea moss) - a fraction of what you'd get from a single serving of beans or a bowl of oats. So while such supplements may offer other forms of gentle support, they are not a meaningful fibre source. For fibre, food is the answer. See our regularity guide for how fibre supports digestion.
Important: If you have a digestive condition like IBS, IBD, or a history of bowel obstruction, talk to your doctor or dietitian before dramatically increasing fibre - the right type and amount can vary, and some high-fibre or high-FODMAP foods can worsen certain conditions. Increase fibre gradually and with plenty of water.