Background Bovine milk-derived oligosaccharides (MOS) containing primarily galacto-oligosaccharides with inherent levels of sialylated oligosaccharides can be added to infant formula to enhance the oligosaccharide profile. Objective To investigate the effects of a MOS-supplemented infant formula on gut microbiota and intestinal immunity. Methods In a double-blind, randomized, controlled trial, healthy-term formula-fed infants aged 21–26 days either received an intact protein cow's milk-based formula (control group, CG, n = 112) or the same formula containing 7.2 g MOS/L (experimental group, EG, n = 114) until age 6 months. Exclusively human milk-fed infants (HFI, n = 70) from an observational study served as reference. Fecal samples collected at baseline, 2.5 and 4 months of age were assessed for microbiota (16S ribosomal ribonucleic acid—based approaches), metabolites and biomarkers of gut health and immune response. Results At age 2.5 and 4 months, redundancy analysis (P = 0.002) and average phylogenetic distance (P < 0.05) showed that the overall microbiota composition in EG was different from CG and closer to that of HFI. Similarly, EG caesarean-born infants were different from CG caesarean- or vaginally-born infants and approaching HFI vaginally-born infants. Relative bifidobacteria abundance was higher in EG vs. CG (P < 0.05) approaching HFI. At age 4 months, counts of Clostridioides difficile and Clostridium perfringens were ∼90% (P < 0.001) and ∼65% (P < 0.01) lower in EG vs. CG, respectively. Mean (95%CI) fecal secretory immunoglobulin A (IgA) in EG was twice that of CG [70 (57,85) vs. 34 (28,42) mg/g, P < 0.001] and closer to HFI. Fecal oral polio vaccine-specific IgA was ∼50% higher in EG vs. CG (P = 0.065). Compared to CG, EG and HFI had lower fecal calcium excretion (by ∼30%) and fecal pH (P < 0.001), and higher lactate concentration (P < 0.001). Conclusions Infant formula with MOS shifts the gut microbiota and metabolic signature closer to that of HFI, has a strong bifidogenic effect, reduces fecal pathogens, and improves intestinal immune response.

Background Adding bovine milk-derived oligosaccharides (MOS) enhances the oligosaccharide profile of infant formula. This study aimed to evaluate the safety and efficacy of a MOS-supplemented infant formula. Methods In this double-blind randomized controlled trial, healthy infants 21–26 days old were either assigned to bovine milk-based, alpha-lactalbumin, and sn-2 palmitate enriched infant formula (control, n = 115) or the same formula with 7.2 g MOS/L (test, n = 115) until aged 6 months. Co-primary endpoints were weight gain through 4 months and stool consistency (validated scale: 1 = watery to 5 = hard). Secondary endpoints included parent-reported GI tolerance, health-related quality of life (HRQoL), and adverse events (AEs). Results Weight gain was similar (p = 0.695); the difference between test and control (mean; 95% CI: 0.29; −1.15, 1.73 g/day) was above the non-inferiority margin (−3 g/day). Test had softer stools than control (mean difference in stool consistency score: −0.31; 95% CI: −0.42, −0.21; P < 0.0001); fewer parental reports of harder stools (OR = 0.32, 95% CI: 0.20, 0.49; P < 0.0001) and less difficulties in passing stool (OR = 0.25, 95% CI: 0.09, 0.65; P = 0.005). Parent-reported GI tolerance and HRQoL were similar between groups as were the overall low AEs. Conclusions MOS-supplemented infant formula is safe and well-tolerated while supporting normal infant growth and promotes softer stooling pattern without increasing parent-reported and physician-confirmed adverse health concerns. Impact This is the first study investigating the addition of bovine milk-derived oligosaccharides to an infant formula enriched with alpha-lactalbumin and elevated levels of sn-2 palmitate, providing safety and efficacy data for such a formula. Term infant formula supplemented with 7.2 g bovine milk-derived oligosaccharides per liter supported normal infant growth, was well-tolerated and safe. Addition of bovine milk-derived oligosaccharides to term infant formula promoted softer stooling pattern and reduced difficulties in passing stool. The study shows that bovine milk-derived oligosaccharide supplemented infant formula is a safe and effective option for healthy term infants who are formula-fed.