What is fibre?
Dietary fibre is a term that is used for plant-based carbohydrates that, unlike other carbohydrates (such as sugars and starch), are not digested in the small intestine and so reaches the large intestine or colon.
Soluble and insoluble fibre
You may have heard of the terms ‘soluble fibre’ or ‘insoluble fibre’– these are words that are sometimes used to describe the types of fibre in our diet. Although scientific organisations argue that these terms are no longer really appropriate, you may see these terms being used, with soluble fibre including pectins and beta glucans (found for example in foods like fruit and oats) and insoluble fibre including cellulose (found for example in wholegrains and nuts). What is important to remember is that fibre-rich foods typically contain both types of fibre.
Fibre rich foods include:
- Wholegrain breakfast cereals, wholewheat pasta, wholegrain bread and oats, barley and rye
- Fruit such as berries, pears, melon and oranges
- Vegetables such as broccoli, carrots and sweetcorn
- Peas, beans and pulses
- Nuts and seeds
- Potatoes with skin
How does fibre benefit health?
Fibre helps to keep our digestive system healthy and helps to prevent constipation. For example, fibre bulks up stools, makes stools softer and easier to pass and makes waste move through the digestive tract more quickly.
The European Food Safety Authority suggests that including fibre rich foods in a healthy balanced diet can improve weight maintenance. Dietary fibre can reduce your risk of:
- Cardiovascular disease (heart disease and stroke) and type 2 diabetes
|Foods such as oats and barley contain a type of fibre known as beta glucan, which may help to reduce cholesterol levels if you consume 3g or more of it daily, as part of a healthy diet.|
- Colorectal cancer (bowel cancer)
|Did you know that the World Cancer Research Fund (WCRF) estimate that 45% of bowel cancer could be prevented through diet, physical activity and weight?|
Fibre and bowel cancer
We know that dietary fibre may help to protect against bowel cancer. Although the reasons for this are not fully understood, this may be because fibre increases stool size, dilutes content and moves it faster through the gut so the amount of time waste products stay in contact with the bowel is reduced. Some types of fibre may also help gut bacteria produce helpful chemicals that can have beneficial effects on the bowel (see below).
Fibre and good bacteria
Research has increasingly shown how important the bacteria in our gut may be to our health, and it has been suggested that a fibre rich diet can help increase the good bacteria in the gut. Some fibre types provide a food source for ‘friendly’ gut bacteria helping them to increase and produce substances which are thought to be protective such as short-chain fatty acids.
How much fibre do we need?
In 2015 the government published new guidelines with a recommendation that the population's fibre intake should increase to 30g a day for adults (aged 17 years and over). On average, we consume much less than this - about 18g per day. Children also need to increase their intake of fibre. Recommended intakes of fibre are shown below.
Recommended intake of fibre
|2-5||15g per day|
|5-11||20g per day|
|11-16||25g per day|
|17 and over||30g per day|
To increase your fibre intake you could:
- Choose a high fibre breakfast cereal e.g. wholegrain cereal like wholewheat biscuit cereal, no added sugar muesli, bran flakes or porridge. Why not add some fresh fruit, dried fruit, seeds and/or nuts.
- Go for wholemeal or seeded wholegrain breads. If your family only typically likes white bread, why not try the versions that combine white and wholemeal flours as a start.
- Choose wholegrains like wholewheat pasta, bulgur wheat or brown rice.
- Go for potatoes with skins e.g. baked potato, wedges or boiled new potatoes – you can eat these hot or use for a salad.
- For snacks try fruit, vegetable sticks, rye crackers, oatcakes, unsalted nuts or seeds.
- Include plenty of vegetables with meals – either as a side dish/salad or added to sauces, stews or curries – this is a good way of getting children to eat more veg.
- Keep a supply of frozen vegetables so you are never without.
- Add pulses like beans, lentils or chickpeas to stews, curries and salads.
- Have some fresh or fruit canned in natural juice for dessert or a snack.
If you need to increase your fibre intake, it is a good idea to so gradually. It is also important to drink plenty of fluids (around 6-8 glasses per day for adults) and to try to be active for at least 150 minutes per week. See How much physical activity do I need?
A healthy, balanced diet can provide enough fibre – especially if you eat your 5 A DAY and choose wholegrain foods and potatoes in skins. Below is an example of foods that together provide more than the recommended amount of fibre over a day. A 7 day meal planner that meets fibre recommendations can be found here https://www.nutrition.org.uk/attachments/article/881/SACN%20guidelines%20meal%20planner.pdf.
|Meal||Food||Quantity||Fibre content (g)|
|1 banana, sliced||100g||1.5|
|wholemeal toast (2 slices)||70g||4.7|
|Dinner||Baked potato with skin, tuna mayonnaise||180g||6.5|
|Salad (lettuce, tomato and cucumber)||138g||1.7|
|Low fat yogurt||150g||0|
|and chopped almonds||13g||1.3|
|Total fibre intake||34.4|
Fibre for the under-2s
Due to a lack of information in children under 2 years, no firm recommendations about how much fibre they need per day have been made. A varied diet from the age of about 6 months with increasing amounts of pulses, fruits and vegetables is encouraged, as is gradually increasing wholegrains, although NHS choices advises to not give only wholegrain starchy foods to under 2s as they may fill the child up before they've taken in the calories and nutrients they need.
Fibre and Irritable Bowel Syndrome (IBS)
People with IBS are usually well aware that diet can play an important part in controlling symptoms, and are often advised to modify the amount of fibre in their diet. For example, the BDA recommend that if symptoms include constipation then gradually increasing fibre intake may help, particularly wholegrains, oats, fruit, vegetables and linseeds as these may help to soften stools and make them easier to pass. If symptoms include diarrhoea though it may be helpful to try reducing intake of some high fibre food such as wholegrain breakfast cereals and breads.
However, there is no "one size fits all" diet for people with the condition. Keeping a food and symptom diary can help monitor your progress. If you need further help, ask your doctor to refer you to a healthcare professional with expertise in dietary management.
For more information on the sources used in this text, please contact [email protected]
Last reviewed January 2018. Next review due January 2021.