Effects of l-theanine on attention and reaction time response

Previous human studies revealed that l-theanine influences brain function. The current study was designed to evaluate the affect of l-theanine (Suntheanine®) on attention and reaction time response in 18 normal healthy University student volunteers. In accordance with preliminary analysis of the manifest anxiety scale (MAS), the subjects were divided into two groups referred to as high anxiety propensity group and the minimal anxiety propensity group. Both groups received l-theanine (200 mg/100 ml water) and placebo (100 ml water) in a double blind repeated measurement design protocol. Assessments were performed for 15–60 min after consumption under a relaxed condition upon exerting an experimentally induced visual attentional task as well as audio response tests. Self-reports of anxiety as State-Trait Anxiety Inventory (STAI) was characterized at post experiments. Alpha bands electroencephalographic activity and heart rate were recorded throughout the trial. The results demonstrate the significant enhanced activity of alpha bands, descending heart rate, elevated visual attentional performance, and improved reaction time response among high anxiety propensity subjects compared to a placebo. However, no significant differences were noticed among subjects with a minimal anxiety propensity. Results evidently demonstrated that l-theanine clearly has a pronounced effect on attention performance and reaction time response in normal healthy subjects prone to have high anxiety.

► This work is a joint contribution of the University of Shiga prefecture and Taiyo Kagaku Co. Ltd.
► The work highlights the l-theanine influences on attention and reaction time response.
► Normal healthy volunteers with high anxiety and with minimal anxiety propensity were employed.
► 200 mg of l-theanine intake was found effective for healthy people with high anxiety propensity.