Dietary prebiotic oligosaccharides are detectable in the faeces of formula‐fed infants

Abstract
Human milk oligosaccharides are not digested during intestinal passage and can be detected in stools. In this study it was investigated whether a prebiotic mixture of low-molecular-weight galacto-oligosaccharides (GOS) and high-molecular-weight fructo-oligosaccharides (FOS) can be detected in stool samples of formula-fed infants. The test formula was supplemented with 0.8 g/dl oligosaccharides (GOS+FOS). In the control formula, maltodextrins were used as placebo. Fecal flora was assessed at the beginning (day 1) and at the end of a 28-d feeding period (day 2). At day 2 the content of galacto- and fructo-oligosaccharides in the stool samples were measured. On study day 1, the number of bifidobacteria was not different among the groups (supplemented group: 7.7 (6.2) CFU/g; placebo group: 8.0 (6.0) CFU/g). At the end of the 28-d feeding period, the number of bifidobacteria was significantly higher in the group fed the supplemented formula when compared to placebo (supplemented group: 9.8 (0.7) CFU/g stool; placebo group: 7.1 (4.7) CFU/g stool; p<0.001). In all infants fed the supplemented formula, GOS and FOS could be identified in the stool samples. That was not the case in infants fed the non-supplemented formula. The present data confirm the bifidogenicity of oligosaccharides and indicate that dietary galacto-oligosaccharides and long chain fructo-oligosaccharides remain during the whole passage in the lumen of the gastrointestinal tract, similarly to human milk oligosaccharides.