1H NMR-based serum metabolomics revealed minor differences between standard formula-fed and B. lactis-supplemented formula-fed rhesus infants. 1H NMR-based serum metabolomics revealed minor differences between standard formula-fed and B. lactis-supplemented formula-fed rhesus infants. Serum hypoxanthine, acetate, and threonine levels were significantly different (P = 7E−05, P = 0.03, and P = 0.001, respectively), as were isoleucine, valine, and allantoin levels (P = 0.04, P = 0.03, and P = 0.02, respectively). Dimethylglycine, leucine, urea, and insulin levels were not significantly different (P = 0.1, P = 0.1, P = 0.1, and P = 0.5, respectively). Data are presented as means ± SEM, and overall P values were determined using rmANCOVA without multiple-comparison correction. Differences at specific time points were determined using independent-sample t tests and are indicated as * (P < 0.05 after FDR adjustment) and ○ (P < 0.05 before FDR adjustment). Data are presented as means ± SEM. Xuan He et al. mSystems 2016; doi:10.1128/mSystems.00128-16