Human milk oligosaccharides, representing the third largest fraction of human milk, have been assigned important protective functions for newborns acting as bifidogenic substrates or as inhibitory agents towards pathogens. Using high-pH anion-exchange chromatography and an enzyme test kit, twenty oligosaccharides and lactose were determined in milk samples of German women from days 3 to 90 postpartum. Twenty-two secretor mothers with Lewis blood group Le(a - b+) synthesised all twenty oligosaccharides, and could be assigned to milk group 1. Five non-secretor mothers (Le(a+b - )) produced all oligosaccharides with the exception of α1,2-fucosylated compounds (milk group 2), whereas three secretor mothers with blood type Le(a - b - ) lacked α1,4-fucosyloligosaccharides, corresponding to milk group 3. Secretor women of milk groups 1 and 3 synthesised significantly higher amounts of total neutral oligosaccharides and of several total core structures (e.g. lacto-N-tetraose) than non-secretor women. Generally, these oligosaccharides significantly decrease during the first 3 months postpartum. By comparing fucosyloligosaccharides within and among the three milk groups, insight into their biosynthesis could be gained. Six acidic oligosaccharides without fucose residues were detected in milk samples of all mothers. Regression analysis confirmed that total acidic oligosaccharides declined threefold during the study period. Milk samples corresponding to the three milk groups exhibited significant qualitative and quantitative differences during the first 3 months of lactation. It can be assumed that particularly milk of non-secretor women (milk group 2) exerts a modified biological protection in the babies in comparison with milks of secretors (groups 1 and 3).

Background: Oligosaccharides may alter postnatal immune development by influencing the constitution of gastrointestinal bacterial flora. Aims: To investigate the effect of a prebiotic mixture of galacto-and long chain fructo-oligosaccharides on the incidence of atopic dermatitis (AD) during the first six months of life in formula fed infants at high risk of atopy. Methods: Prospective, double-blind, randomised, placebo controlled trial; 259 infants at risk for atopy were enrolled. A total of 102 infants in the prebiotic group and 104 infants in the placebo group completed the study. If bottle feeding was started, the infant was randomly assigned to one of two hydrolysed protein formula groups (0.8 g/100 ml prebiotics or maltodextrine as placebo). All infants were examined for clinical evidence of atopic dermatitis. In a subgroup of 98 infants, faecal flora was analysed. Results: Ten infants (9.8%; 95 CI 5.4-17.1%) in the intervention group and 24 infants (23.1%; 95 CI 16.0-32.1%) in the control group developed AD. The severity of the dermatitis was not affected by diet. Prebiotic supplements were associated with a significantly higher number of faecal bifidobacteria compared with controls but there was no significant difference in lactobacilli counts. Conclusion: Results show for the first time a beneficial effect of prebiotics on the development of atopic dermatitis in a high risk population of infants. Although the mechanism of this effect requires further investigation, it appears likely that oligosaccharides modulate postnatal immune development by altering bowel flora and have a potential role in primary allergy prevention during infancy.

A mixture of neutral short-chain galactooligosaccharides (scGOS) and long-chain fructooligosaccharides (lcFOS) has been shown to reduce the incidence of atopic dermatitis (AD) and infectious episodes during the first 6 mo of life. This dual protection occurred through the intervention period. The present study evaluated if these protective effects were lasting beyond the intervention period. In a prospective, randomized, double-blind, placebo-controlled design, healthy term infants with a parental history of atopy were fed either a prebiotic-supplemented (8 g/L scGOS/lcFOS) or placebo-supplemented (8 g/L maltodextrin) hypoallergenic formula during the first 6 mo of life. Following this intervention period, blind follow-up continued until 2 y of life. Primary endpoints were cumulative incidence of allergic manifestations. Secondary endpoints were number of infectious episodes and growth. Of 152 participants, 134 infants (68 in placebo, 66 in intervention group) completed the follow-up. During this period, infants in the scGOS/lcFOS group had significantly lower incidence of allergic manifestations. Cumulative incidences for AD, recurrent wheezing, and allergic urticaria were higher in the placebo group, (27.9, 20.6, and 10.3%, respectively) than in the intervention group (13.6, 7.6, and 1.5%) (P < 0.05). Infants in the scGOS/lcFOS group had fewer episodes of physician-diagnosed overall and upper respiratory tract infections (P < 0.01), fever episodes (P < 0.00001), and fewer antibiotic prescriptions (P < 0.05). Growth was normal and similar in both groups. Early dietary intervention with oligosaccharide prebiotics has a protective effect against both allergic manifestations and infections. The observed dual protection lasting beyond the intervention period suggests that an immune modulating effect through the intestinal flora modification may be the principal mechanism of action.

ContextOligosaccharides are the third largest solid component in human milk. These diverse compounds are thought to have numerous beneficial functions in infants, including protection against infectious diseases. The structures of more than 100 oligosaccharides in human milk have been elucidated so far.ObjectiveThe aim of this review was to identify the main factors that affect the concentrations of oligosaccharides in human milk and to determine whether it is possible to calculate representative and reliable mean concentrations.Data SourcesA comprehensive literature search on oligosaccharide concentrations in human milk was performed in 6 electronic databases: BIOSIS, Current Contents Search, Embase, Lancet Titles, MEDLINE and PubMed.Study SelectionThe initial search resulted in 1363 hits. After the elimination of duplicates, the literature was screened. The application of strict inclusion criteria resulted in 21 articles selected.Data ExtractionOligosaccharide concentrations, both mean values and single values, reported in the literature were sorted by gestational age, secretor status of mothers, and defined lactation periods.ResultsMean concentrations, including confidence limits, of 33 neutral and acidic oligosaccharides reported could be calculated. Concentrations of oligosaccharides in human milk show variations that are dependent on both the secretor type of the mother and the lactation period as examined by analyses of variance. In addition, large interlaboratory variations in the data were observed.ConclusionsWorldwide interlaboratory quantitative analyses of identical milk samples would be required to identify the most reliable methods of determining concentrations of oligosaccharides in human milk. The data presented here contribute to the current knowledge about the composition and quantities of oligosaccharides in human milk and may foster greater understanding of the biological functions of these compounds.

SCFAs (short-chain fatty acids), fermentation products of bacteria, influence epithelial-specific gene expression. We hypothesize that SCFAs affect goblet-cell-specific mucin MUC2 expression and thereby alter epithelial protection. In the present study, our aim was to investigate the mechanisms that regulate butyrate-mediated effects on MUC2 synthesis. Human goblet cell-like LS174T cells were treated with SCFAs, after which MUC2 mRNA levels and stability, and MUC2 protein expression were analysed. SCFA-responsive regions and cis-elements within the MUC2 promoter were identified by transfection and gel-shift assays. The effects of butyrate on histone H3/H4 status at the MUC2 promoter were established by chromatin immunoprecipitation. Butyrate (at 1 mM), as well as propionate, induced an increase in MUC2 mRNA levels. MUC2 mRNA levels returned to basal levels after incubation with 5-15 mM butyrate. Interestingly, this decrease was not due to loss of RNA stability. In contrast, at concentrations of 5-15 mM propionate, MUC2 mRNA levels remained increased. Promoter-regulation studies revealed an active butyrate-responsive region at -947/-371 within the MUC2 promoter. In this region we identified an active AP1 (c-Fos/c-Jun) cis-element at -818/-808 that mediates butyrate-induced activation of the promoter. Finally, MUC2 regulation by butyrate at 10-15 mM was associated with increased acetylation of histone H3 and H4 and methylation of H3 at the MUC2 promoter. In conclusion, 1 mM butyrate and 1-15 mM propionate increase MUC2 expression. The effects of butyrate on MUC2 mRNA are mediated via AP-1 and acetylation/methylation of histones at the MUC2 promoter.

Background: The establishment of a balanced intestinal microflora which may protect against infection is desirable for the preterm infant. Objective: To investigate the effect of a preterm formula milk supplement consisting of oligosaccharides in similar proportions to human milk on the faecal flora and stool characteristics of preterm infants. Study design: To resemble the effect of human milk, an oligosaccharide mixture consisting of 90% galacto-oligosaccharides and 10% fructo-oligosaccharides was used to supplement a standard preterm formula at a concentration of 10 g/l. This supplemented formula was studied in 15 preterm infants, and the results were compared with those found in 15 infants fed a formula supplemented with maltodextrin as placebo. A group fed fortified mother's milk was investigated as a reference group (n = 12). On four days during a 28 day feeding period (1, 7, 14, and 28), the faecal flora was investigated, and stool characteristics, growth, and possible side effects were recorded. Results: During the study period, the number of bifidobacteria in the group fed the oligosaccharide supplemented formula increased to the upper range of bifidobacteria counts in the reference group. The difference between the supplemented and non-supplemented groups was highly significant (p = 0.0008). The stool characteristics were also influenced by the supplement: the stool frequency after 28 days was significantly lower in the control group than in the oligosaccharide supplemented group (p = 0.0079) and the reference group (p < 0.0001). Over the study period, the stool consistency in the control group became harder, but remained fairly stable in the other two groups. There was no effect of the different diets on the incidence of side effects (crying, regurgitation, vomiting) or on weight gain or length gain. Conclusion: Supplementing preterm formula with a mixture of galacto-and fructo-oligosaccharides at a concentration of 10 g/l stimulates the growth of bifidobacteria in the intestine and results in stool characteristics similar to those found in preterm infants fed human milk. Therefore prebiotic mixtures such as the one studied may help to improve intestinal tolerance to enteral feeding in preterm infants.

The gastrointestinal tract of neonates becomes colonized immediately after birth with environmental microorganisms, mainly from the mother; strong evidence suggests that the early composition of the microbiota of neonates plays an important role for the postnatal development of the immune system. The present study was designed to evaluate by means of a molecular biology approach the relation between the intestinal ecosystem of the newborn and the mode of delivery. The intestinal bacterial composition on d 3 of life was investigated in 23 infants born by vaginal delivery and in 23 infants delivered by cesarean section. PCR-denaturing gradient gel electrophoresis and PCR-temperature gradient gel electrophoresis have been utilized, together with the specific amplifications for 10 Bifidobacterium species, 3 Ruminococcus species, and Bacteroides. The intestinal microbiota of neonates delivered by cesarean delivery appears to be less diverse, in terms of bacteria species, than the microbiota of vaginally delivered infants. The intestinal microbiota after cesarean delivery is characterized by an absence of Bifidobacteria species. Vaginally delivered neonates, even if they showed individual microbial profiles, were characterized by predominant groups such as B. longum and B. catenulatum. Our data demonstrate that the mode of delivery has a deep impact on the composition of the intestinal microbiota at the very beginning of human life. This study opens the path to further investigations to confirm the link between microbiota composition and immune system development and to identify tools for the modulation of the intestinal microbiota of cesarean-delivered neonates. Additionally, we underline the importance of adequate microbiological tools used to support clinically relevant trials, if intestinal microbiota is considered as a study outcome.

Feeding infants breast milk of healthy mothers is associated with a lower incidence of infectious and allergic diseases. Although this effect is of multifactorial origin, it is widely accepted that the entire intestinal flora of breast-fed infants provides antiinfective properties and is an important stimulating factor for the postnatal development of the immune system. The effect of human milk on the postnatal development of the intestinal flora cannot be attributed to a single ingredient. It is generally accepted, however, that human milk oligosaccharides play a key role in this matter. Apart from their prebiotic effects, there is also evidence that human milk oligosaccharides act as receptor analogs to inhibit the adhesion of pathogens on the epithelial surface and interact directly with immune cells. Because of their complexity, oligosaccharides with structures identical to human milk oligosaccharides are not yet available as dietary ingredients. In the current search for alternatives, non-milk-derived oligosaccharides have gained much attention. As 1 example, a mixture of neutral galacto-oligosaccharides and long chain fructo-oligosaccharides have been identified as effective prebiotic ingredients during infancy. Furthermore, another class of oligosaccharides with a potential physiological benefit could be those found in animal milks. Most of the oligosaccharides detected in domestic animal milks have some structural features in common with human milk oligosaccharides. One important fact is the occurrence of sialic acids such as N-acetylneuraminic acids. However, total amounts and individual structures are still different from those in human milk oligosaccharides. Although these structural similarities between animal milk and human milk oligosaccharides are promising, further studies are needed to prove the equivalence of their function.