dietary fibre

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Material mostly derived from plant cell walls which is not digested by human digestive enzymes but is partially broken down by intestinal bacteria to volatile fatty acids that can be used as a source of energy. A large proportion consists of non-starch polysaccharides (NSP); these include soluble fibre that reduces levels of blood cholesterol and increases the viscosity of the intestinal contents: and insoluble fibre (cellulose) that acts as a laxative. Earlier known as roughage or bulk.

Part of food that cannot be digested and absorbed. The term is sometimes used to distinguish fibre in the diet from crude fibre, a chemical analytical form of fibre. See also fibre.