A whey-predominant formula induces fecal microbiota similar to that found in breast-fed infants

To compare the effects of a whey-predominant infant formula and breast milk on the gut microbiota, growth, and tolerance of infants, we conducted an open, prospective, parallel-group study in healthy newborn infants. A total of 60 infants were enrolled, and 55 completed the study. Of the 55 infants, 21 were breast-fed and 34 were fed a whey-predominant study formula that had low phosphate concentration (31 mg/100 kcal), was reduced in protein (1.8 g/100 kcal or 0.43 g/kJ), had lactose as the sole carbohydrate source, and had an amino acid profile and buffering capacity similar to that of human milk. At 30 and 60 days of age, fecal bacterial counts were determined using fluorescence in situ hybridization and culture plating, and growth and digestive tolerance were evaluated. There were no differences in fecal bacterial counts between formula-fed and breast-fed infants at either 30 or 60 days. Fecal counts of bifidobacteria, lactobacilli, clostridia, enterococci, and Enterobacteriacea were similar in the 2 groups using both bacterial enumeration methods. Growth and digestive tolerance were also similar in the 2 groups. Thus, this whey-predominant infant formula is safe and well tolerated, and it affects infants' microbiota in a similar manner as observed with breast milk.