The effect of a prebiotic supplemented formula on growth and stool microbiology of term infants.

Background: The intestinal flora of breast-fed infants is generally dominated by bifidobacteria which have beneficial properties. Their presence is due to various compounds of breast milk including prebiotic substances.

Aim: This prospective, double blind, study compared the growth, acceptability and the proportion of bifidobacteria and clostridia in the stool flora of bottle-fed infants randomized to receive a formula with a specific mixture of 0.4 g/100 ml prebiotic galacto- and long-chain fructooligosaccharides or the same formula without added prebiotics.

Methods: Within 0-14 days after birth at term, healthy bottle-fed infants were enrolled to receive either a prebiotic formula or a standard formula. At recruitment anthropometric measurements were done. These were repeated at the age of 6 and 12 weeks. Stool samples were taken at inclusion and at the age of 6 weeks. The number of bifidobacteria and clostridia was determined by fluorescent in situ hybridization.

Results: There was good tolerance of the prebiotic formula. Somatic growth was similar in the two groups. Stool frequency was significantly higher in the prebiotic group (P=0.031). Infants in the prebiotic group had also softer stools as compared to the control group (P=0.026). Baseline values of microorganisms at study entry were similar. The percentage of faecal clostridia at the completion of the study was significantly lower in the prebiotic group (P=0.042), while the proportion of faecal bifidobacteria was higher in the prebiotic group as compared to the control group. However this difference did not reach statistical significance (P=0.262). The percentage of E. coli was lower in the prebiotic group but again this did not reach statistical significance (P=0.312).

Conclusion: An infant formula containing prebiotic oligosaccharides is well tolerated, leads to normal somatic growth and suppresses the numbers of clostridia in the faeces with a trend for higher percentage of stool bifidobacteria and lower percentage of E. coli.