Prebiotic Effect of Nonmilk Oligosaccharides

Because there is a broad consensus that the intestinal microbiota plays an important physiological role for the host, many attempts have been made to influence the intestinal microbiota by dietary interventions. 

More recently, the latter prebiotic concept was revised. The authors come to the definition that prebiotics have to be resistant until they are fermented by the intestinal (i.e., not only colonic) flora. The balanced stimulation of growth and/or activity of the health-promoting bacteria in the gastrointestinal tract have to be demonstrated finally by performing studies in the target group to produce sound scientific data (36). 

More recently, products combining both principles as synbiotics are under discussion (37). 

The most extensively studied prebiotic oligosaccharides are GOS and FOS, and together with the disaccharide lactulose, they are the only nonmilk oligosaccharides with an approved prebiotic status (36). 

The low digestibility—an essential prerequisite to act as a prebiotic— has been demonstrated for GOS and IcFOS (58). A mixture of these two oligosaccharides has been introduced in the market in 2001. The bifidogenic effect of this mixture was shown in several studies in formula-fed preterm (Table 3) and term (Table 2) infants. As in the animal experiment, the effect depends on the dosage (46). At a concentration of 0.8 g/dl (this corresponds to the concentration of neutral oligosaccharides in human milk), the number of bifidobacteria was tantamount to that found in feces of breastfed infants. The bifidogenic effect was associated with a reduction of the stool pH (46,48) as well as a reduction of pathogenic bacteria (48,59). 

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