Effect of Formula Composition on the Development of Infant Gut Microbiota

Objectives: Breast-feeding induces a gut microbiota rich in bifidobacteria, whereas formula-fed babies have a more diverse colonization. This ecosystem contributes to the development of the immune response and the lower incidence of diarrhea and allergy in breast-fed infants. This randomized double-blind controlled trial aimed to evaluate the bifidogenic effect of a mainly whey protein study formula low in phosphate and protein, allowing a composition closer to that of human milk. Patients and Methods: One hundred ninety healthy infants exclusively received study formula with or without Bifidobacterium longum (BL999), or a control formula for up to 4 months. Breast-fed infants served as a reference population. Stool samples collected at 2 months of age were analyzed for bacterial counts (log colony-forming unit [CFU]/g). Results: Bifidobacteria counts were significantly higher in infants receiving the study formula alone (10.0[0.8], P < 0.0001, median [interquartile range]) or with BL999 (9.8[1.4], P < 0.01) than control (9.2[3.5]), and were similar to breast-fed infants (10.1[0.4], P > 0.05). The difference between the 2 study groups was 0.16 log CFU/g (90% confidence interval [CI] [0-0.4]), within the predefined equivalence margin. Microbiota profile, as a percentage of total bacteria counts, showed about 50% Bifidobacteria, 8% Enterobacteria, and < 10% Clostridia in study formulae and breast-fed infants versus 22%, 13%, and 19% in controls, respectively. There were no significant differences in growth measurements, digestive tolerance, and adverse events between groups. Conclusions: This study showed that infant formula closer resembling human milk was more bifidogenic than the control formula and led to a microbiota profile similar to that for breast-fed infants.