ObjectivesThe aim of this study was to compare the effects of an infant formula fortified with nucleotides (NF) with those of a control formula (CF) on the incidence of diarrhea, respiratory tract infections (RTIs), and immune responses in healthy term infants.MethodsThis 12-month, double-blind study was conducted on 1- to 7-day-old infants randomized to receive NF or CF exclusively until 12 weeks of age, and fed the assigned formula with solid food until 12 months. NF was supplemented with 72 mg/L of nucleotides, based on the total potentially available nucleotide content of human milk. Subjects were evaluated within 1 week of birth, at 4 weeks, and every 4 weeks thereafter until 48 weeks of age. The primary outcome variable was the incidence of diarrhea. Secondary variables included RTIs, serum immunoglobulin concentrations, and response to hepatitis B vaccine.ResultsCompared with subjects fed CF (n = 170), those fed NF (n = 166) had a trend toward reduced risk of diarrhea from 8 to 48 weeks of age and a significantly lower risk of 25.4% (P= 0.05) between 8 and 28 weeks. NF subjects had significantly higher serum immunoglobulin A concentrations (P< 0.05) throughout the 48-week study. The NF group had an increased risk of upper RTIs, the same incidence of lower RTIs, and the same antibody response to hepatitis B vaccination as the CF group, based on one-sided tests. Growth was normal in both groups, and no adverse events were considered to be formula-related.ConclusionsHealthy term infants from 8 to 28 weeks of life are less likely to experience diarrhea and have higher serum immunoglobulin A concentrations with NF compared with formula without added nucleotides.