Fibre…what is it exactly and why is it so important?


Dietary fibre plays a key role in a healthy diet. It is essential for maintaining a well-tuned digestive system and has been shown to benefit diabetes and weight control, and to prevent heart disease and some cancers.

Sadly 72% of men and 87% of women in the UK are not eating the recommended intake of 18g per day (1). A deficiency in fibre can cause a number of serious health issues and at the least cause irregular digestion.

So what exactly is fibre?

Fibre, or ‘roughage’ as it is sometimes known, is the indigestible part of cells found in plants (fruits, vegetables and whole grains). We do not break down and absorb fibre when we eat it, as we do with other foods, and instead it passes through our digestive system. For this reason we do not gain any nutrients or energy from fibre (it is a zero calorie carbohydrate) but it does add bulk to our food which helps in moving things through our digestive tract – including harmful toxins.

Fibre comes in two forms, soluble and insoluble. Soluble fibre dissolves in water. When mixed with water it forms a gel-like substance and swells. It can help lower blood cholesterol and glucose levels. You may see soluble fibre listed on foods as pectins or gums. Good sources of soluble fiber include oats, peas, beans, apples, oranges, carrots, barley and psyllium.

Insoluble fibre does not dissolve in water and passes through the digestive tract staying almost in its original form. It promotes the movement of material through our bodies and can be of benefit to those who struggle with constipation or irregular stools. You may see insoluble fibre listed on foods as cellulose or lignins. Insoluble fibre is found mainly in whole grains and also in nuts, cauliflower, green beans, dark leafy vegetables and fruit.

Food Serving Total Fibre (g) Insoluble Fibre (g) Soluble Fibre (g)
Apple 1 Medium 3.7 2.7 1
Broccoli 1 Cup 4.6 2.3 2.3
Carrot (raw) 1 Cup 3.3 1.7 1.6
Cous Cous 1 Cup 2.7 2.1 0.6
Dates 1 Cup 13.4 11.2 2.2
Lentils 1 Cup 15.6 14.4 1.2
Oatmeal (Porridge) 1 Cup 3.1 1.3 1.8
Orange 1 Medium 3.1 1.3 1.8
Peas 1 Cup 8.8 6.2 2.6
Walnuts 1 Cup 5.8 4.0 1.8

In the average diet about ¾ of fibre eaten is insoluble and ¼ is soluble as people tend to eat more grain based foods (bread and cereal) and not enough fruit and vegetables!

While there is no amount of fibre that is considered toxic, it should be introduced gradually into your diet to allow the digestive system to adapt. It is also wise to increase water intake (good advice for most people in any event) to allow for the extra water that will be absorbed by soluble fibre. Good ways of increasing fibre intake are to:

  •  start to eat more raw fruit and vegetables,
  • add seeds to salads, or eat a seed and nut mix as a snack
  • use brown rice and whole meal pasta in place of white versions
  • eat the skins of root vegetables where possible
  • include chickpeas and lentils in a curry
  • buy foods containing whole grains

Finally, eating sufficient amounts of fibre has been shown to help with weight control by increasing the feeling of fullness and reducing the total amount of calories eaten in a meal by about 20% while also helping to improve blood sugar levels.

If a healthier digestive system, reduced cholesterol and blood glucose, and a lower risk of colon cancer aren’t good enough reasons to include proper amounts of fibre in your diet, then the fact that it can help to control your weight might just convince you to introduce more fibre in your diet from today!

© Blueprint Health and fitness, 2015


(1) The National Diet and Nutrition Survey, published 2014