THE EFFECTS OF INFANT FORMULAS CONTAINING EITHER PREBIOTICS OR PROBIOTICS ON THE FAECAL LACTOBACILLUS POPULATION

Abstract

Aim: The intestinal microbiota of breast-fed infants is generally dominated by the genera Bifidobacterium and Lactobacillus. The intestinal microbiota composition is regarded as an important factor for the infants' health and well being, and several Lactobacillus species have been reported to inhibit pathogens or to stimulate the immune system. In this study the effects of infant formulas containing either prebiotics or probiotics on the percentage of faecal lactobacilli were studied. Methods: At birth, infants of whom the mother had decided not to breast- feed, were at random and double blindly allocated to one of the four formula groups. In total 36 infants received standard infant formula; 19 received a prebiotic formula containing a specific mixture of 0.6 g/100 ml GOS/FOS (ratio 9:1), 17 received a prebiotic formula containing 0.6 g/100 ml GOS and 19 received a probiotic formula containing 6.0 × 109 viable cells/100ml Bifidobacterium animalis Bb12 (ProF). A group of 101 breast-fed infants was included as a reference group. Faecal samples taken on age d5 and w12 were analysed, using a newly developed duplex 5′nuclease PCR assay to determine the percentage of lactobacilli. Results: In the breast-fed group, the percentages of lactobacilli increased significantly between d5 and w12 from 1.1 ± 0.4% to 6.4 ± 1.2% (mean ± SEM; p = 0.001). The GOS/FOS group also showed an increase of lactobacilli resulting in a significantly higher percentage of lactobacilli than in the standard formula group (6.1 ± 2.6% vs. 0.9 ± 0.4%; p = 0.007) at w12. No significant differences were found between GOS (1.1 ± 0.4%) or ProF (2.4 ± 1.7%) versus the standard formula group at w12. Conclusion: Addition of GOS/FOS to the standard infant formula stimulates the percentage of faecal lactobacilli similar to that found in breast-fed infants. In contrast no stimulation of lactobacilli was shown with standard infant formula or after the addition of 0.6g/100 ml GOS or viable Bifidobacterium animalis Bb12 to the standard formula.