Physiological effects of non-digestible oligosaccharides

Abstract

Most dietary oligo/polysaccharides are quantitatively hydrolysed in the upper part of the gastrointestinal tract. But, either because of the configuration of their osidic bonds or because of, still not fully understood, peculiar physiochemical properties, some of the dietary oligo/polysaccharides do resist, more or less quantitatively, the digestive process. Once they have reached the caeco-colon, most (but not necessarily all) of the non-digestible oligo/polysaccharides are hydrolysed to small oligomers and monomers which are further metabolized by anaerobic bacteria. Such a metabolic process is known as fermentation. Even though they do not provide the body with monosaccharides, the non-digestible oligo/polysaccharides are, thus, indirect energy substrates and metabolic regulators. An important class of dietary non-digestible saccharides is that composed of short (up to 10 monomers) and medium (up to 50-60 units) chain-length homopolymers. These are the non-digestible oligosaccharides or NDO. This review aims at discussing the physiological effects of NDO by focusing more on the fructans, which have been so far the most studied compounds. The main points discussed are the biotransformation and physiological effect of NDO in the gastrointestinal tract and their systemic effects with special attention accorded to their influence on lipid metabolism and on bioavailability of macro- and micronutrients. © 1994 Academic Press.