Health benefits of non-digestible oligosaccharides.

Non-digestible oligosaccharides are complex carbohydrates of the non-a-glucan type which, because of the configuration of their osidic bonds, resist hydrolysis by salivary and intestinal digestive enzymes. In the colon they are fermented by anaerobic bacteria. Among the non-digestible oligosaccharides, the chicory fructooligosaccharides occupy a key position and, in most european countries, they are recognised as natural food ingredients. The other major products are the short chain fructooligosaccharides and galactooligosaccharides obtained by enzymatic synthesis using sucrose and lactose as substrates respectively, the soybean oligosaccharides, the xylooligosaccharides produced by partial hydrolysis of xylans and polydextrose or pyrodextrins prepared by a chemical treatment of carbohydrates. The most well known effect of most non-digestible oligosaccharides, and in particular of the fructooligosaccharides, is the selective stimulation of the growth of Bifidobacteria thus modifying significantly the composition of the colonic microbiota. Such a modification, which has clearly been demonstrated in human volunteers, is meant to be benificial in part because it is accompanied by a significant reduction in the number of bacteria reported to have pathogenic potential. Within the framework of research and development of "functional foods", such an effect justifies a "functional claim" for fructooligosaccharides namely "bifidogenesis". They are also typical "prebiotics". Besides their bifidogenic effect, the chicory fructooligosaccharides have additional nutritional properties on digestive physiological parameters like colonic pH and stool bulking which justify their classification as dietary fibers. Moreover, in experimental models, it has also been reported that they improve the bioavailability of essentiel minerals and that they reduce serum triglyceridemia by lowering hepatic lipogenesis. Such effects demonstrate interactions between the chicory fructooligosaccharides and key functions in the body but their significance for humans still need to be proven before being used to justify additional claims.