Why is fibre important?

Profile picture of Iona Bell
Specialist Dietitian, Cromwell Hospital
28 December 2022
Next review due December 2025

Many of us don’t get enough fibre in our diets. But why is fibre so important for our health? And how can you make sure you are getting enough of it? Here, I’ll explain the reasons why fibre is good for you and share my tips for getting more of it into your diet each day.

chickpea and spinach casserole

What is fibre?

Fibre is a plant-based carbohydrate found in foods such as wholegrains and vegetables. You might also have heard it described as roughage. Your small intestines usually digest the food you eat but with fibre it’s different. Instead, the bacteria that live in your large intestine ferment the plant fibres, either partially or fully.  Fibre can also be separated into the below categories.

1. Soluble fibre

This fibre is easily broken down by the bacteria in your large intestine. Soluble fibre can help lower your blood glucose and cholesterol levels. You can find it in oats, beans, lentils, and fruit.

2. Insoluble fibre

This fibre is not broken down as easily by the bacteria in your gut. Insoluble fibre attracts water and can help prevent you from getting constipated. You can find insoluble fibre in wheat bran, vegetables, and wholegrains.

3. Prebiotics

This is a type of carbohydrate that feeds your gut bacteria. Prebiotics can help more good bacteria to grow in your gut. You can find prebiotics in garlic, onions, banana and asparagus.

4. Resistant starch

This fibre is broken down by the ‘good’ bacteria in your gut to produce short chain fatty acids. Short chain fatty acids help to keep your gut lining strong and can reduce inflammation in your intestines. They may also reduce your risk of colorectal cancers. You can find resistant starch in green bananas, oats, cooked and cooled potatoes, as well as beans and legumes.

Why is fibre good for you?

Below are five health benefits of having a fibre rich diet.

1. Constipation

Dietary fibre can help to stimulate your bowel and can also add bulk to your poo. This means it can be easier for you to go to the toilet. It’s important that you’re drinking enough water too, as this will help the fibre to do its job.

2. Better digestive health

Fibre is essential for your gut to work properly. It feeds the good bacteria in the large intestine, which helps you to have a diverse and healthy microbiome (range of gut bacteria). This can help to reduce intestinal inflammation and can also lower your risk of both diverticulitis and colon cancer.

3. Reduced risk of cardiovascular disease

Oats and barely contain a soluble fibre called beta-glucan, which forms a gel like substance in your gut. Beta-glucan can bind to cholesterol to help stop it being absorbed into body. This helps reduce your blood cholesterol levels.

4. Improved blood sugar control

Eating fibre-rich food can help to control your blood sugar. This is because fibre-rich foods don’t spike your blood sugar levels as much as low-fibre options. Studies have shown that people who eat lots of wholegrains have a lower risk of type 2 diabetes than those who eat refined carbohydrates such as white bread.

5. Better weight management

While more evidence is needed, current studies show that eating fibre-rich foods can help you to maintain a healthy weight. This may be because high-fibre foods keep you feeling fuller for longer and so you may eat less overall.

How much fibre do you need?

For adults, it’s recommended that you aim for 30g of fibre per day. However, many of us fall short of this requirement. The average adult in the UK only consumes around 18g per day, so it’s important to try and increase this amount through dietary changes.

How to get more fibre into your diet

To benefit from a fibre-rich diet, you’ll need to consume fibre from different plant-based sources, as they all have different benefits. Below are some of the best ways to eat more fibre.

Switch to wholegrain

Wholegrain products contain more fibre than their white alternative. This applies to pasta, rice, crackers, cereals, and breads. Try substituting white pasta for wholewheat pasta or try wholemeal, rye, granary and high-fibre bread.

Eat more beans and pulses

Eating lots of beans, pulses, and lentils is a good way of getting extra fibre into your diet. Try having a mixed bean salad with tuna and red onions, making a lentil dahl, or adding kidney beans into your chilli.

Load up on veg

Vegetables contain a variety of fibre. Try filling half of your plate with at least two different coloured vegetables at your main meal. You could also add salad to sandwiches and choose vegetable sticks as a snack. Adding in garlic, onions, and asparagus will also give you some prebiotic fibres.

Don’t forget the fruit

Whole fruit is also a good source of fibre. But fruit juice is a low-fibre option, so try to focus on having fruits such as berries, dried fruit, or apples.

Check your labels

If you’re purchasing ready-made products, try to choose high-fibre options. Foods that are considered high in fibre contain at least 6g of fibre per 100g. Try to avoid products with less than 3g of fibre per 100g as these would be low fibre choices.

It’s important to increase your fibre intake slowly, as eating lots of additional fibre too quickly can cause gas and bloating. And remember to drink enough water and stay physically active for good digestive health.

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Profile picture of Iona Bell
Iona Bell
Specialist Dietitian, Cromwell Hospital

    • Fibre. British Nutrition Foundation., accessed 1 November 2022.
    • Fibre. British Association of Dietitians., accessed 1 November 2022.
    • Personal communication. Ioana Bell, Specialist Dietitian, Cromwell Hospital.

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