PREBIOTIC OLIGOSACCHARIDES IN INFANT NUTRITION: ADDITION OF ONLY GALACTOOLIGOSACCHARIDES DOES NOT INDUCE FAECAL ACIDIC PH AND SCFA-SPECTRUM TYPICAL FOR BREAST FED INFANTS

Abstract

Introduction: Recently, the ESPGHAN Committee on Nutrition summarised available information on the effects of adding prebiotic oligosaccharides to infant formulae. The Committee commented that only the combination of galactooligosaccharides (GOS) and fructooligosaccharides (FOS) was tested in controlled infant feeding studies and that future trials should define optimal quantity and quality of oligosaccharides with prebiotic function. We present data on a study with an infant formula supplemented with only GOS. These data can be compared with those from a previous study where a formula with a mixture (90% GOS and 10% FOS) is investigated using an identical protocol, formula matrix and analytical methods. Methods: Before birth, infants from mothers intending to formula feed were at random and double blindly allocated to one of two formula groups. From birth until 16 weeks of age, the GOS formula group (n = 17) received formula supplemented with 0.6 g/100 ml GOS. The standard group (n = 17) received the infant formula without supplementation. Faecal samples were taken from the diapers at postnatal days 5, 10, and weeks 4, 8, 12 and 16. Percentage of bifidobacteria from total number of bacteria (analysed by fluorescence in situ hybridisation), total and relative amounts of short-chain fatty acids (SCFA), lactate concentration and pH were measured in faeces. Parallel to the two formula groups a breast-feeding group was followed using the same protocol. Results: Both formula groups revealed a highly similar development of faecal bifidobacterial flora. Faecal pH (6.5-7.0), SCFA total concentration (75-90 mmol/kg wet faeces) and -profile (acetate: 70-80%) were also very similar between both formula groups, but distinct from the breast feeding group (pH: 5.5-5.7; SCFA: 50-60 mmol/kg faeces; acetate: >85%). Under highly similar conditions nearly identical results were found earlier for a group fed standard formula (n = 19) and a parallel breast-fed group. However, the prebiotic group (n = 19) fed formula supplemented with 0.6 g/100ml GOS/FOS mixture clearly showed different faecal characteristics (pH 5.5-6.0; SCFA: 65-75 mmol/kg faeces; acetate: >80%), close to the ones for breast fed infants. Conclusions: In contrast to infant formula supplemented with a GOS/FOS mixture, infant formula supplemented with short chain GOS only, does not induce faecal acidic pH and SCFA-spectrum typical for breast-fed babies. This result supports the hypothesis that the long chain FOS components of the prebiotic mixture are fermented rather slowly, similar to polymeric human milk oligosaccharides, leading to a typical acidic pH and acetate-dominating SCFA spectrum in the distal part of the colon and the faeces.