Dietary fibreDietary fibre is the portion of carbohydrates which is not broken down by digestive enzymes and which reaches the large intestine unchanged. All polysaccharides except starch are dietary fibre. Dietary fibre includes cellulose, hemicellulose, pectin, lignin and plant gums. Resistant starch is sometimes included as a form of dietary fibre. The variation between different forms of dietary fibre is considerable.
The physiological differences in dietary fibre can be related to the differences in chemical and physical composition of the fibre components. The gastrointestinal transit time is determined largely by the amount of insoluble fibre.
Gel-forming, soluble dietary fibre has a favourable effect on the blood sugar level and the insulin response following a meal, and can even reduce the blood cholesterol level. The dietary fibre levels, determined with the AOAC method, for oat bran, wheat bran, "kruska" (a purified wheat bran) and sugar beet fibre are 18%, 40%, 50% and 67%, respectively.
|Oat bran||Wheat bran|
"Kruska"(wheat bran with a high dietary fibre content)
|Sugar beet fibre |
|Dietary fibre is often used to increase the dietary fibre content and improve the keeping qualities of bread. |