What is fibre?

We’re always being told to eat more fibre for good health, but do you really know why? This guide gives you all the information you need about this important nutrient

Written by Madeleine Bailey on February 14, 2019 Reviewed by Amanda Hamilton on February 24, 2019

Fibre does far more than keep your digestive system moving – this nutrient can lower your risk of developing serious diseases, like stroke, diabetes and heart disease. Yet nine in 10 Brits don’t get the 30g a day that they need.^1,2

What exactly is fibre?

It’s actually a complex carbohydrate found in plant cells that can’t be digested or absorbed by the small intestine. Instead, it’s broken down inside the large intestine by bacteria for food.³

The different types of fibre

Fibre comes from plant foods and has certain characteristics including fermentability, solubility and viscosity. These properties influence what happens in the body once it is consumed, and the positive effects of that consumption. Almost all fibres contain these properties, but in different proportions. The main types of dietary fibre are: 1. Soluble This type of fibre – found in oats, peas, beans, apples, citrus fruits, carrots, barley and nuts – dissolves in your digestive system to form a gel-like substance,⁴ which is digested by friendly bacteria in the large intestine.⁵ Soluble fibre softens stools so they’re easier to pass. 2. Insoluble By contrast, insoluble fibre doesn’t dissolve in the gut and so can’t be digested. This means it adds bulk to your stools, and so helps food to be pushed through your digestive system.⁶ Sources of insoluble fibre include wheat bran, brown rice, cauliflower, potatoes, tomatoes, cucumbers, carrots and nuts.⁷ 3. Resistant starch This type of starch is classed as a fibre because it isn’t digested in your stomach or small intestine, but instead becomes food for the friendly bacteria in your colon, boosting gut health. Found in cooked then cooled potatoes, green bananas, cashew nuts and raw oats,⁸ it’s thought to bulk up stools and speed their journey through the colon.⁹

Why is fibre important for our health?

Getting enough fibre isn’t just about encouraging regular bowel movements:

It can support your heart health

A 2010 study by Australia’s University of Queensland found soluble fibre can reduce levels of blood cholesterol,¹⁰ lowering risk of heart disease and strokes. Meanwhile, a 2015 study reported that eating a high-fibre diet is associated with lower blood pressure.¹¹

It can help you regulate your blood sugar

Australian researchers also found that soluble fibre slows the rate at which sugar is absorbed into your blood – helping to blunt blood sugar spikes.¹² It’s thought it does this by delaying the rate at which your stomach empties of food.¹³

It can help you manage your weight

Fibre helps you feel fuller, satisfying your appetite. A 2015 study in Annals of Internal Medicine reported that people who made it their goal to eat 30g of fibre a day lost on average 2.1kg after 12 months.¹⁴

It may help you live longer

A 2019 report in The Lancet found that people eating more than 25g per day are 15–30% less likely to die from any cause, including heart disease and diabetes, than those eating under 15g. Scientists found people eating more fibre led to overall lower blood pressure, weight and cholesterol levels.¹⁵

How much fibre do we need?

Adults need 30g a day, according to the NHS – but most only get 18g. Children need:¹⁶

• 2-5 years – 15g
• 5-11 years – 20g
• 11-16 years – 25g

A 50g serving of porridge with a medium banana gives you 7g of fibre, a handful of almonds 3g and a skin-on baked potato served with baked beans is 12.4g.^17,18

How to eat more fibre

It isn’t just about eating more beans and vegetables. You need to increase your intake slowly to allow your gut to adjust – avoiding symptoms like bloating and gas. And drink more fluids – fibre absorbs water so you need to drink enough to keep stools soft; aim for 8-10 glasses of fluid, ideally water, a day. Also try these high-fibre ideas:¹⁹

• make your own muesli with rolled oats, nuts, seeds and sliced banana
• stir beans and lentils into stews, curries and sauces
• try overnight oats or traditional porridge with toppings such as natural yoghurt, chopped banana and a teaspoon of Manuka honey
• eat the potato skin after enjoying a jacket spud
• choose wholegrain versions of starchy carbohydrates including rice, pasta and bread
• swap starchy carbs for fibre-rich alternatives such as plant-based pasta or quinoa
• snack on oatcakes, vegetable sticks, nuts and seeds

Shop Food & Drink Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies. Sources  1. James Gallagher. BBC News. The lifesaving food 90% of us aren’t getting enough of 2. NHS. How to get more fibre into your diet 3. British Dietetic Association. Food fact sheet: Fibre 4. Mayo Clinic. Dietary fibre: Essential for a healthy diet 5. Jennifer Huizen. Medical News Today. Soluble and insoluble fibre: what is the difference? 6. As above 7. As Source 5 8. Kris Gunnars. Healthline. Resistant Starch 101: Everything you need to know 9. Lockyer S, Nugent AP. Health effects of resistant starch 10. Gunness P, Gidley MJ. Mechanisms underlying the cholesterol-lowering properties of soluble dietary fibre polysaccharides 11. Evans CE, et al. Effects of dietary fibre type on blood pressure: systematic review and meta-analysis of randomized controlled trials of healthy individuals 12. As Source 10 13. Williams BA, et al. Gut Fermentation of Dietary Fibres: Physico-Chemistry of Plant Cell Walls and Implications for Health 14. Ma Y, et al. Single-component versus multicomponent dietary goals for the metabolic syndrome: a randomized trial 15. Reynolds A, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses 16. NHS. How to get more fibre into your diet 17. As Source 3 18. As Source 16 19. As Source 3