My mum used to call it roughage, and it is almost impossible to have missed the various health claims for what happens when you eat it. Now we are even being told that certain bits of fibre are better than others; but what is it?

Fibre can be roughly defined as the indigestible part of plant based food. Measuring the amount of fibre in food has proved problematic, so as a result of these technical difficulties you will find reference to non starch polysaccharides (NSP) as well as dietary fibre in literature on the subject.

The differences is that dietary fibre includes NSP, but that NSP, as a defining category does not include all that is dietary fibre. Instead NSP is a method of measuring what in a food constitutes the indigestible portion. The reason for referring to NSP is that NSP is the main component in plant cell walls, and therefore is the largest single contributor to the ‘fibre’ content of a food, and can be relatively easily measured to give food scientists a reasonably accurate and reliable measurement tool.

When you look closely at fibre it is best thought of as a family; its members are complex carbohydrates, and not all of them are fibrous in structure. There are two main classes of fibre, soluble and insoluble.

Bonus effects
If there were not already enough benefits to convince you that a health fibre intake is a dietary priority then it is worth remembering that foods which pack the fibre also pack vitamins and minerals.

By eating a variety of fibre rich foods you will also be getting a wide spectrum of vitamins, minerals, as well as phytonutrients each with their own unique health benefits; like the cancer preventative effect of the pigment lycopene found in tomatoes, or the anti-inflammatory action of lutein found in spinach.

Don’t just think of eating fibre, but think of all that goes with it too.

Eating right for Fibre
Eating a healthy amount of fibre is not difficult, even if the average UK resident only eats half the recommended amount. Eating five portions of fruit and vegetables a day should be enough to ensure a healthy fibre intake (interestingly the average UK resident averages around half the five a day).

Moving from an average intake to the recommended intake needs to be done carefully taking a week or more to build up. If you don’t then you risk a dramatic decrease in transit time – otherwise known as diarrhoea.

Fibre and fluid
A healthy fluid intake, that is at least 1.5 litres a day, is always a good idea. When you eat a good fibre-full diet it is especially important. Dietary fibre acts much like a sponge, when you eat it the fibre tends to be dry, without fluid to lubricate it becomes a tough job to get it through to the other end.

To illustrate this, get a sponge and try and push it through the cardboard tube in the middle of a toilet roll – dry this is not easy, wet the sponge and it slides through. The same is true for your body, if you do not supply the fluid you need to help the passage then some will be pulled from other parts of your body – but essentially the fibre is going through dry.

Dry fibre passing through you is not healthy – it cannot perform its proper function without out adequate hydration. Like your brain, your gut performs best when well hydrated!

Fibre Damage
Fibre can be broken down manually, cooking and chewing has some effect breaking fibre up a little. However the effect is not so much that it causes concern day to day.

Blending, juicing and smoothie making do substantially alter the structure of the fibre component of fruits and vegetables. Mechanically breaking the structure to make a liquid out of fruit and vegetables effectively destroys a substantial part of the fibre content and this is why to date a juice or smoothie still only counts as one of your five a day.

Depending on what is removed when the drink is made you may find that the vitamin and mineral count has suffered along with the fibre content.