A human dietary supplement comprises theacrine and optionally other compounds that modulate the effects of theacrine. Uses for the theacrine-containing supplement include improvement of at least one of mood, energy, focus, concentration or sexual desire or a reduction of at least one of anxiety or fatigue. A synergistic composition comprises co-administration of theacrine and caffeine, wherein the co-administered caffeine reduces theacrine oral clearance (CL/F) and oral volume of distribution (Vd/F). In addition, the co-administered caffeine increases area under the plasma concentration time curve (AUC) of theacrine, and increases theacrine maximum plasma concentration (C
