Definition of Dietary Fiber

Definition of Dietary Fiber
Because dietary fiber is not a constant entity, no universally accepted definition for this food component has yet evolved. Probably the most widely accepted definition for dietary fiber is that: plant polysaccharides and lignin which are resistant to hydrolysis by the digestive enzymes of man.

Dissatisfaction with this definition exists because

• It fails to include all the indigestible residue from food that may reach the colon.

• It uses ability to be digested as the basis for identifying fiber. All undigested food reaching the colon does not necessarily lack the ability to be digested nor is necessarily unavailable to the body.

Starch in varying amounts reaches the colon in an unaltered state along with the truly indigestible polysaccharides (nonstarch polysaccharides). Starch and much of the nonstarch polysaccharides fermentation by colonic bacteria, thereby producing short-chain fatty acids that may be used for energy by the host.

Despite their presence in colonic residue, starch and lignin are not considered by some researcher as true components of dietary fiber, starch because it is a non-carbohydrates polymer. It is generally agreed that all of the nonstarch polysaccharides should be regarded as fiber components. Dietary fiber, in spite of the controversy about its exact composition, is derived from plant cells. The plant cell wall is all particular importance in providing the non starch polysaccharides, also plant cell wall is the source of lignin.
Definition of Dietary Fiber