Cognitive function is critical for successful prolonged performance in eSports. This double-blind placebo-controlled study examined the effect of an inositol-enhanced arginine silicate oral supplement on cognitive performance and energy in eSports athletes. Sixty healthy men and women who spent 5 or more hours a week playing video games were randomly assigned to take supplement or placebo for 7 days. On day 1 and 7, before and 15 min after dosing, subjects completed the Trail Making Test (TMT), Parts A and B; Stroop Test; and Profile of Mood States (POMS) questionnaire, and then played a video game for 60 min. Immediately after, cognitive tests were repeated. Self-reported energy levels increased, anger decreased, and TMT-B test errors decreased in the supplement group compared to placebo (