Dietary fibre differs from other nutrients in that it is not digested in the small intestine. Instead, some of it undergoes changes in the large intestine which can have a variety of effects on the body. Dietary fibre is a mixture of different substances. Some of these can 'dissolve' in water (soluble fibre) and the description of dietary fibre as roughage and fibrous can be misleading.

Dietary fibre from different sources differ in the relative amount of each of their components. For example, wheat bran contains high amounts oi insoluble fibre while oat bran has high amounts of soluble fibre. Because each component has different chemical and biological properties, the biological result of consuming dietary fibre from different foods differs.

Examine snacks as well as main meals to find out where fats (spreads and oils, and cooking fat in cakes and pastries) and refined carbohydrate (sugar in confectionery and biscuits) can be replaced with foods containing dietary fibre (see the following sources of dietary fibre).

Dietary fibre is mostly carbohydrate (and a little 'lignin') which is not digested in the small intestine but may be fermented in the large intestine. It is 'non-starch polysaccharide'. However, some starch resists digestion too, and behaves like dietary fibre. Unripe or partially ripe bananas are a good source of resistant starch and dietary fibre. Dietary fibre has important functions in the large bowel and some breaks down there under the consuming (kilojoules) at about 13 kilojoules per gram of dietary fibre (3 kilocalories).

It is best to obtain dietary fibre from a variety of foods because its chemistry is different in different foods and its effects on food structure differ from food to food.

Dietary fibre can be obtained from the following foods:
Barley Green leafy types
(cabbage, spinach, silver beet, etc.)
Rice Legumes (beans, peas)
Rye Mushrooms and fungi
Wheat Root types (potatoes, carrots, swedes, etc.)
Almonds Japanese and Korean foods
Apple Citrus
Pear Stone
Berry Tropical

There is currently a great deal of interest in particular source of dietary fibre like wheat bran, oat bran and rice bran, each with somewhat different properties some of which are probably yet to be identified. The food from which they come may also have useful effects which should not be neglected. It would bl a pity to have oat bran and ignore hot porridge or muesli!

Dietary fibre supplements should only be used where there is a specific medical need for them, such as:

Remember that too much of one particular kind of fibre may lead to reduced absorption of elements (minerals) like calcium zinc and iron (see VEGETARIANS ARE OFTEN ANAEMIC).