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

Nutr Neurosci. 2010 Dec;13(6):283-90. doi: 10.1179/147683010X12611460764840.

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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Affect / drug effects
  • Attention / drug effects*
  • Blood Pressure / drug effects
  • Caffeine / administration & dosage*
  • Cognition / drug effects*
  • Double-Blind Method
  • Fatigue
  • Female
  • Glutamates / administration & dosage*
  • Heart Rate / drug effects
  • Humans
  • Male
  • Placebos
  • Reaction Time
  • Tea / chemistry

Substances

  • Glutamates
  • Placebos
  • Tea
  • Caffeine
  • theanine