The fibre in your diet

How many of us think about the dietary fibre content of our diet? I am not sure many do judging by the latest figures showing the average daily intake of fibre for adults living in the UK falls well below the recommended 30g per day. Women in the UK consumer a daily average of 17g of fibre and men manage just 20g.

But what does dietary fibre do in the body and how necessary is it really?

What is dietary fibre?

Dietary fibre, used to be known as ‘roughage’ and is commonly associated with the coarse, bland tasting breakfast cereals used to manage constipation.

Dietary fibre is basically the parts of plants that cannot be digested by the upper part of the digestive tract. It consists of all sorts of plant materials including complex carbohydrates, tough fibres called lignin and naturally occurring waxes.

There are many different types of dietary fibre such as beta glucan, the soluble, gel like fibres contained in oats as well and the coarse fibres contained in whole grains such as wheat bran. The different fibres have an amazingly diverse effect on the physiology of the body.

What does fibre do in the body?

Originally it was thought that dietary fibre had no nutritional value and it only acted as a bulking agent keeping the contents of the gut moving along nicely.

We now know dietary fibre can be fermented by gut bacteria to produce energy, nutrients and other valuable components which can be absorbed into the blood stream. Some of these components can improve the immune system and mental health (see also our previous post - How gut bacteria keep you healthy.

How good is dietary fibre for our health?

Fibre and heart health

Diets rich in fermentable fibre, and in particular oats, have been shown to reduce low density lipoprotein (LDL) and cholesterol in the blood.

Fibre and type 2 diabetes

Dietary fibre has been shown to improve blood glucose levels and has an important role in preventing and managing diabetes.

Fibre and obesity

Foods high in fibre tend to have a high volume and not many calories (low energy density). They may help to reduce hunger, promote a sense of fullness and play a role in weight management. Eating foods high in fibre can bring about a reduction in intake of other less healthy foods.

Diverticulitis[1] and colo-rectal cancer

Evidence suggests a protective effect of eating a diet rich in dietary fibre on diverticulitis and colo-rectal cancer.

Which foods contain dietary fibre?

Eating a wide variety of unprocessed plant based foods improves the amount and type of fibre in the diet.

Here are some examples of how much fibre is contained in 20 common foods:

[1] Diverticulitis is when the diverticula (small bulges or pockets in the lining of the intestine) become inflamed or infected and cause symptoms such as pain, rectal bleeding and, or fever.