Caffeine

Summary

What is it? Caffeine is a stimulant found in coffee, tea and energy drinks, and sold as capsules and powders. Its FDA substance code (UNII) is 3G6A5W338E.

Why would I need it? People use it to feel more alert and to react faster. So far this page covers one question: do supplements, mostly caffeine, help esports players? The page will grow as more papers are added.

Is it useful? Possibly, for reaction speed and thinking tasks in esports players, but the evidence is low certainty. A 2026 meta-analysis of 13 trials found a pooled effect of g = 0.92, and a bias-adjusted estimate of 0.49 ^{[1]Effects of nutritional interventions on competitive performance and dose‒response relationships among esports players of different skill levels: a systematic review and three-level meta-analysis. Yao J, He J, Hu E. J Int Soc Sports Nutr, 2026}. For safety, the European Food Safety Authority says single doses up to 200 mg and intakes up to 400 mg a day do not raise concerns for healthy adults ^{[2]Caffeine: safety of caffeine. European Food Safety Authority (EFSA)}.

FAQ

Does caffeine help esports players? Possibly. Nine of the 13 trials in a 2026 meta-analysis used a product that contained caffeine, and the pooled result was positive, but the certainty was low for most outcomes. ^{[1]Effects of nutritional interventions on competitive performance and dose‒response relationships among esports players of different skill levels: a systematic review and three-level meta-analysis. Yao J, He J, Hu E. J Int Soc Sports Nutr, 2026}

How much caffeine is safe? EFSA says a single dose of up to 200 mg, about 3 mg/kg of body weight, from all sources does not raise safety concerns for healthy adults. It gives 400 mg a day as the limit for adults who are not pregnant. A dose of 100 mg close to bedtime may disturb sleep in some adults ^{[2]Caffeine: safety of caffeine. European Food Safety Authority (EFSA)}.

Which doses did esports trials use? Mostly 2 to 3 mg/kg, or a fixed 200 mg, in one dose before testing ^{[1]Effects of nutritional interventions on competitive performance and dose‒response relationships among esports players of different skill levels: a systematic review and three-level meta-analysis. Yao J, He J, Hu E. J Int Soc Sports Nutr, 2026}.

Article

What it is

Caffeine is a plant compound that stimulates the nervous system. Its FDA registry entry gives the substance name CAFFEINE and the code 3G6A5W338E ^{[3]CAFFEINE (UNII 3G6A5W338E). FDA Global Substance Registration System}.

What the evidence says

A 2026 systematic review and meta-analysis pooled 13 randomised trials with 743 esports players. Supplements improved reaction speed (g = 1.18) and executive function, meaning flexible thinking and decision-making (g = 1.06). Attention did not improve significantly. The certainty of the evidence was low for four of five outcome groups, and a test for publication bias suggested the effect was overstated ^{[1]Effects of nutritional interventions on competitive performance and dose‒response relationships among esports players of different skill levels: a systematic review and three-level meta-analysis. Yao J, He J, Hu E. J Int Soc Sports Nutr, 2026}. A 2021 meta-analysis in sport found that caffeine improved attention, accuracy and speed ^{[4]Caffeine and Cognitive Functions in Sports: A Systematic Review and Meta-Analysis. Lorenzo Calvo J, Fei X, Domínguez R, et al. Nutrients, 2021}.

Safety

EFSA gives 200 mg as a single dose and 400 mg a day as limits that do not raise concerns for healthy adults. It excludes pregnant women from the daily limit ^{[2]Caffeine: safety of caffeine. European Food Safety Authority (EFSA)}.

Talk to a doctor before you start a supplement, especially if you take medicines or are pregnant.

Verification

Checked on 2026-11-10.