Growth, Gastrointestinal Tolerance and Stool Characteristics of Healthy Term Infants Fed an Infant Formula Containing Hydrolyzed Whey Protein (63%) and Intact Casein (37%): A Randomized Clinical Trial

To investigate whether healthy term infants, fed an infant formula containing hydrolyzed whey protein (HWP-F, hydrolyzed whey/intact casein =63/37), differ in growth, gastrointestinal tolerance and stool characteristics from those fed an infant formula containing intact whey protein (IWP-F, intact whey/intact casein =61/39) or breast milk. Healthy term infants, born within 14 days of the study's commencement, were randomly assigned to be fed IWP-F or HWP-F until 13 weeks of age, and breast-fed (BF) infants were enrolled as a reference group. Anthropometric measurements, gastrointestinal tolerance indexes and stool characteristics were assessed at baseline, and 7 and 13 weeks of age. There were no significant differences in any growth measurements and the occurrence of crying, spit-up and difficult defecation among the three feeding groups during the study period. However, daily feeding frequency was consistently lower in the formula-fed infants than in the BF group throughout the study (p < 0.05), and infants in the HWP-F group consumed more formula than those in the IWP-F group at 7 and 13 weeks of age (p ≤ 0.002). The HWP-F-fed infants had more similar stool characteristics to the breast-fed infants than infants in the IWP-F group at 13 weeks of age, regardless of frequency, volume, color or consistency of stool. This study demonstrates that the HWP-F could support the normal growth of healthy term infants, to a comparable extent to that of breast-fed infants during the first three months of life. Moreover, stool characteristics of HWP-F-fed infants are much closer to breast-fed infants than IWP-F-fed infants, but no significant gastrointestinal tolerance improvement was observed in HWP-F group.