ABSTRACT
Dietary ber is dened as “the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine” (AACC 2001). e primary source of dietary ber is the plant cell wall, which forms a continuous extracellular matrix extending through the whole structure of the
plant. Cellulose microbrils form the basic structural framework into which diverse matrix polysaccharides are deposited, and are common to all classes of plant, ~30% of wall polymers. Key matrix components include NSPs, oligosaccharides, lignin (a cross-linked complex polymer of phenylpropane subunits), and associated plant substances (Asp 1987, Ha et al. 2000, Anderson et al. 2009). NSPs include cellulose, hemicelluloses, pectins, and arabinoxylans (Blackwood et al. 2000). e denition of dietary ber was expanded in the mid-1970s by Trowel and colleagues to include nondigestible polysaccharides, such as mucilages and gums (Anderson et al. 2009). Although these nondigestible polysaccharides have been found to have physiological actions attributed to dietary ber, their origins within the cell wall remain elusive (Buttriss and Stokes 2008, DeVries 2003).
