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Randomized Controlled Trial
. 2010 Dec;13(6):283-90.
doi: 10.1179/147683010X12611460764840.

The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness

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Randomized Controlled Trial

The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness

T Giesbrecht et al. Nutr Neurosci. 2010 Dec.

Abstract

The non-proteinic amino acid L-theanine and caffeine, a methylxanthine derivative, are naturally occurring ingredients in tea. The present study investigated the effect of a combination of 97 mg L-theanine and 40 mg caffeine as compared to placebo treatment on cognitive performance, alertness, blood pressure, and heart rate in a sample of young adults (n = 44). Cognitive performance, self-reported mood, blood pressure, and heart rate were measured before L-theanine and caffeine administration (i.e. at baseline) and 20 min and 70 min thereafter. The combination of moderate levels of L-theanine and caffeine significantly improved accuracy during task switching and self-reported alertness (both P < 0.01) and reduced self-reported tiredness (P < 0.05). There were no significant effects on other cognitive tasks, such as visual search, choice reaction times, or mental rotation. The present results suggest that 97 mg of L-theanine in combination with 40 mg of caffeine helps to focus attention during a demanding cognitive task.

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