Bifidogenic effects of solid weaning foods with added prebiotic oligosaccharides: a randomised controlled clinical trial.

Objectives: Breast-fed infants have relatively high proportions of faecal bifidobacteria. This bifidogenic microbiota is at least partly explained by the high levels of prebiotic oligosaccharides in human milk. The present study aimed at testing the effect of solid foods with added prebiotic galacto- and fructo-oligosaccharides (GOS/FOS) on the composition of the intestinal microbiota of fully formula-fed infants during the weaning period.

Methods: The study was a double-blind, randomised trial with an intervention period of 6 weeks. Infants aged 4 to 6 months who were about to start consuming solid foods were randomised to receive either weaning products with a mixture of GOS/FOS or control weaning products with maltodextrin. After an adjustment period, the presented daily dose of GOS/FOS was 4.5 g. Total numbers of bacteria and bifidobacteria in faecal samples were analysed with fluorescent in situ hybridization.

Results: Thirty-five infants were included in the study, and 20 infants were included in a per-protocol analysis. In the GOS/FOS group, the faecal percentage of bifidobacteria significantly increased from 43% to 57% (P = 0.031) from week 0 to week 6, but did not significantly change in the control group (36% and 32%, respectively; P = 0.387). The change in the percentage of bifidobacteria between week 0 and week 6 in the GOS/FOS was significantly different from this change in the control group (P = 0.026).

Conclusions: We conclude that addition of GOS/FOS to solid foods induces an increase in the faecal proportion of bifidobacteria in the intestinal microbiota of fully formula-fed infants with an established, mixed-type microbiota in the weaning period.