L-Theanine Promotes Relaxation and Attention

A recent study reports that L-theanine enhances attention, relaxation and reaction time. L-theanine is an amino acid found primarily in green tea. Previous research suggests that L-theanine crosses the blood-brain barrier and influences brain function.

Eighteen healthy university students were included in this double-blind placebo controlled study. The subjects were divided into two groups based on propensity towards high or low levels of unease and frustration. The subjects in both groups received 200 mg of L-theanine in 100 ml of water and a placebo of 100 ml of water alone on separate occasions. The subjects were evaluated 15-60 minutes after ingestion of the L-theanine or placebo using visual attention tasks and audio response tests. The subjects also completed a State-Trait Anxiety Inventory test to determine levels of unease and frustration. Heart rate and electrical activity in the brain using electroencephalography (EEG) was also measured.

The study found that in the subjects with the higher propensity for unease and frustration, L-theanine supplementation resulted in reduced heart rate and enhanced activity of alpha bands on the EEG, which are associated with relaxation. In addition, L-theanine supplementation resulted in enhanced performance on visual attention tasks and reaction time in the subjects with increased propensity towards unease and frustration. No change was noted in the group of subjects with low propensity towards unease and frustration.

The study authors stated that the results demonstrated that L-theanine clearly has a pronounced effect on attention performance and reaction time response in normal healthy subjects prone to have high levels of unease and frustration.

Reference:

Higashiyama A, Htay HH, Ozeki M, Juneja LR, Kapoor MP. Effects of L-theanine on attention and reaction time response. J Funct Foods. 2011 Apr 19. Published Online Ahead of Print.