Prebiotics and probiotics in infant nutrition

IntroductionIn general breast-fed infants suffer less from infection, which could be partly explained by the specificcompostionand metabolic activity of their intestinalmicroflora. During the last two decades, many attempts have been made to mimic the intestinal flora of breast fed infants in formula fed infants. Bothprebioticsandprobioticsbased concepts have been developed to beneficially change the intestinalmicrofloraand thus induce positive health effects. We conducted two infant nutrition studies with the objective to compare the effects of infant formulas containing eitherprebioticsorprobioticsin infants on the composition (%bifidobacteriaand lactobacilli) and metabolic activity (short chain fatty acid profile, lactate concentration and pH) of the intestinalmicrofloraand on Indicators of development of thesecretoryimmune response (faecalSlgAconcentration).Study designIn both studies, infants were enrolled within 3 days after delivery and followed during the first 32 weeks of life. Except for the intervention, the design of both studies was identical. Infants of whom the mothers decided not to breast-feed, were at random and double blindly allocated to one of the formula groups. A group of breast-fed infants was included as a reference. The first study, included 63 infants that were breast fed, 19 fedaregular, non-supplemented infant formula, 19 received infant formula containing a mixture of 0.6 g/100ml GOS (90%) and FOS (10%), 19 received standard formula containing 6.0x109 /100ml viableBifidobacteriumanimalis strain Bb-12. The second study included 38 infants on breast milk, 17 on standard,unsupplementedformula and 17 on formula containing 0.6 g/100ml GOS. During intervention, parents were asked to take faeces samples from the diaper of their infants on postnatal day 5, 10, 28 and once every 4 weeksthereafter.ResultsThe GOS/FOS-, GOS-, Bb-12 formula aUinduced an intestinalmicrofloradominated bybifidobacteria(59.2%7.7%, 76.5:1:2.6% and 69.7:1:2.7%mean:l:SEMresp. at 16w) and no significant differences were found compared to the standard formula group (56:1:6.4%). In contrast, we did show a significant effect of GOS/FOS on the percentage of lactobacilli (6:1:2.6% at 12w, p=0.OO7) compared to the standard formula group (1:1:0.4%), whereas no significant effect was found for the GOS- and Bb-12 formula (1:1:0.4% and 2.4:1:1.7%resp. at 12w).Infants fed on GOS/FOS formula showed a metabolic activity of the flora comparable to that of breast fed infants. GOS/FOS formula induced a faecal SCFA profile (acetate/propionate/ butyrate/others) comparable to that found in breast fed infants (82/14/2/2% vs. 90/6/2/2% at 16w), whilethat of GOS- and Bb-12 fed infants is more like that in standard formula fed infants (78/16/3/2 and 70/22/6/3 vs. 73/20/5/3 at age 16w). We also demonstrated that the faecal lactate concentration of the GOS/FOS group was comparable to breast fed infants (40.9:1:10.7 vs. 45.2%9.0mmollactate/kg faeces), whereas that of GOS- and Bb-12 fed infants was more like standard formula fed infants (12.2:1:5.1 and 6.1 :1:4.2 vs. 0.8:1:0.7). Also the faecal pH of the GOS/FOS group was highly comparable to that in breast-fed infants (5.6:1:0.2 vs. 5.7:1:0.3), whereas that of GOS- and Bb-12 fed infants was more comparable to that of standard formula fed infants (pH 6.5:1:0.3 and 6.6:1:0.2 vs. 7.1:1:0.2).Finally we showed that the GOS/FOS formula group showed a marked trend towards higher faecalSigAlevels compared to the standard formula group (0.84 (0.6-1.8) vs. 0.39 (0.1-0.9), median (P25-P75), p=0.015 at age 16w), which could not be demonstrated in the GOS and Bb-12 infant formula groups.CondusionAlthough, more research is needed to elucidate the effects of GOS/FOS formula on hard clinical endpoints, based on our findings it can bereasonably assumed that infants fed onGOS/FOSwill have a healthbenefit compared to infants fed on standard infant