A randomized crossover study was conducted to compare the effects of caffeine, caffeine + Dynamine + TeaCrine, and placebo on cognition, mood, and biomarkers of arousal among 50 young male egamers. The study also measured electroencephalogram power during cognitive tasks and tested whether individual differences in xenobiotic metabolism would affect study outcome measures. The results of the study could help identify safe nutritional supplements to improve egamer performance.