1) A study analyzed body fluids (saliva, semen, blood serum, and urine) from 21 healthy subjects using NMR spectroscopy. 2) Samples were collected and prepared for NMR analysis by centrifugation, drying, and reconstitution in deuterium oxide. 3) The NMR spectra identified characteristic metabolites for each body fluid, such as citrate in semen, lactate in saliva and serum, and creatinine in urine.