Background: Green tea is traditionally known to induce mental clarity, cognitive function, physical
activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the
world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher
intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine,
L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance.
These effects were observed when these phytochemicals were consumed separately and in combination.
Methods: A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive
effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance.
Conclusion: Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and
self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine
alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined
were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser
extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the
amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and
caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover,
L-theanine was found to lead to relaxation by reducing caffeine induced arousal.