Human milk oligosaccharides (HMOs) are multifunctional carbohydrates naturally present in human milk that act as prebiotics, prevent pathogen binding and infections, modulate the immune system and may support brain development in infants. HMOs composition is very individualized and differences in HMOs concentrations may affect the infant’s health. HMOs variability can be partially explained by the activity of Secretor (Se) and Lewis (Le) genes in the mother, but non-genetic maternal factors may also be involved. In this cross-sectional, observational study, 78 single human milk samples ranging from 17 to 76 days postpartum (median: 32 days, IQR: 25–46 days) were collected from breastfeeding Brazilian women, analyzed for 16 representative HMOs by liquid chromatography coupled to mass spectrometry and associations between maternal and infant factors with HMOs concentrations were investigated. HMOs concentrations presented a high variability even in women with the same SeLe phenotype and associations with maternal allergic disease, time postpartum and with infant’s weight, weight gain and sex. Overall, we present unprecedented data on HMOs concentrations from breastfeeding Brazilian women and novel associations of maternal allergic disease and infant’s sex with HMOs concentrations. Differences in HMOs composition attributed to maternal SeLe phenotype do not impact infant growth, but higher concentrations of specific HMOs may protect against excessive weight gain.

Human milk oligosaccharides (HMOs) are free glycans naturally present in human milk that act as prebiotics, prevent pathogen binding, modulate the immune system and support brain development in infants. The HMOs composition and concentrations vary significantly among different women mainly because of the direct influence of the Secretor and Lewis phenotypes on HMOs biosynthesis. Analytical methods that can identify the differences in the HMOs composition and concentrations are a fundamental tool in HMOs research. This paper describes a simple HMOs extraction and analysis for the simultaneous and absolute quantification of neutral and acidic HMOs by graphitized carbon liquid chromatography-electrospray ionization-mass spectrometry. This method was validated and applied to analyze HMOs in the human milk obtained from 10 women. This method allows accurate and reliable quantification of HMOs and can be used to determine differences in HMOs concentrations throughout lactation and among women with different Secretor and Lewis phenotypes.

Background: Exclusive breastfeeding promotes beneficial modifications on the microbiota of cesarean born infants, but little is known about the role of specific breast milk components in this modulation. Women with an active FUT2 gene (calledsecretors) secrete α1–2 fucosylated human milk oligosaccharides (HMOs), which promoteBifidobacteriumin the infant’s gut and may modulate the microbiota of cesarean born infants.Objective: To compare the microbiota composition of cesarean and vaginally born infants breastfed by secretor mothers.Methods: Maternal secretor status was determined by the occurrence of 4 different α1–2 fucosylated HMOs in breast milk by LC-MS. The fecal microbiota composition from cesarean and vaginally born infants was analyzed by 16S rRNA gene sequencing and qPCR, stratified by the maternal secretor status, and compared.Results: Alpha and beta diversity were not significantly different in cesarean born, secretor-fed infants (CSe+) compared to vaginally born, secretor-fed infants (VSe+). There were no significant differences in the fecal relative abundance ofBifidobacteriumbetween CSe+ and VSe+ infants, but the prevalence of the speciesB.longumwas lower in CSe+. The fecal relative abundance ofBacteroideswas also lower, whileAkkermansiaandKluyverawere higher in CSe+ infants.Conclusion: Cesarean and vaginally born infants fed with breast milk containing the α1–2 fucosylated HMOs fraction present similar amounts ofBifidobacteriumin the feces, but differences are observed in other members of the microbiota.

An analytical method based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) was validated and applied for the analysis of aflatoxin M₁ (AFM₁), ochratoxin A (OTA) and deoxynivalenol (DON) in infant formula and milk-based products for young children commercialized in Brazil. A total of 38 samples were evaluated, including 12 infant formula, 14 follow-on formula and 12 samples of milk-based products. AFM₁ was detected in 12 (32%) samples, and seven (18%) samples contained AFM₁ levels above the method limit of quantification in a concentration range between 0.013 and 0.067 ng mL⁻¹ (0.026 ± 0.019). Two samples of milk-based products exceeded the maximum level (ML) fixed by the European Union for AFM₁ in baby foods, however, all samples were in agreement with the levels established by the Brazilian regulation. OTA and DON were not detected in any of the analyzed samples.

There is a lack of studies investigating the clinical benefits of prebiotic-supplemented infant formula. In this study, healthy infants that started, on medical recommendation, artificial feeding with one of 2 infant formulas containing 4 g/L of GOS/FOS (9:1) (IF4 group; n = 60) or 8 g/L of GOS/FOS (9:1) (IF8 group; n = 60) were followed for 30 days to the evaluation of growth and gastrointestinal symptoms. Exclusively breastfed infants (EBF; n = 60) were followed up as a reference. Both infant formulas supported adequate weight gain, however, IF4 formula promotes growth more similar to breastfed infants. There was no additional benefit of a dose higher than 4 g/L of GOS/FOS on gastrointestinal symptoms.

Breast milk is rich in bioactive components, especially human milk oligosaccharides (HMOs), which are crucial for establishing gut microbiota. The 2′-FL (2-Fucosyllactose), one of the most abundant oligosaccharides in breast milk, functions as a selective prebiotic. Objective: To examine the effect of adding 2′-FL (2-Fucosyllactose) to an infant formula containing prebiotic galacto-oligosaccharides (GOSs) and fructo-oligosaccharides (FOSs) on the gut microbiome of healthy formula-fed infants. Methods: This study enrolled infants from three groups: an HMO experimental group (n = 29), a GOS/FOS control group (n = 30), and an exclusively breastfed (breast milk [BM]) reference group (n = 28). Fecal samples from the three groups in the first and fourth months of life were analyzed. The V3 and V4 regions of the 16S rRNA gene were amplified and sequenced on the Illumina MiSeq. ANOVA, Kruskal–Wallis, richness indices (Chao1, Shannon), UniFrac distances, and the Adonis tests were used to perform statistical analyses on the relative abundance of phyla and genera, as well as the alpha and beta-diversity of the gut microbiota. Results: After intervention, Actinobacteriota emerged as the predominant phylum in both the HMO (60.4%) and BM (46.6%) groups. Bifidobacterium and Escherichia-Shigella were identified as the two most abundant bacterial genera in both groups. Nevertheless, the statistical analysis showed that the relative abundance of Bifidobacterium in the HMO formula-fed group after intervention was similar to that in the BM group (p > 0.05). Infants in the HMO and GOS/FOS groups showed higher relative abundance of [Ruminococcus]_gnavus_group bacteria compared to those in the BM group. Groups fed with infant formula demonstrated higher alpha-diversity of gut microbiota compared to breastfed infants (p < 0.05), at the time of admission as well as after the intervention. Beta-diversity was significantly different among the three groups, according to type of feeding. Infants fed a 2′-FL-supplemented infant formula exhibited growth comparable to that of breastfed infants throughout the intervention period, demonstrating that the formula was both safe and well tolerated. Conclusions: Adding 2′-FL to an infant formula containing 4 g/L of GOS + FOS resulted in a stronger bifidogenic effect compared to the formula without 2′-FL.