Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study.
- 2021-04
- Journal of medicinal food 24(4)
- Yoshitake Baba
- Shun Inagaki
- Sae Nakagawa
- Toshiyuki Kaneko
- Makoto Kobayashi
- Takanobu Takihara
- PubMed: 33751906
- DOI: 10.1089/jmf.2020.4803
Study Design
- Type
- Randomized Controlled Trial (RCT)
- Population
- Japanese men and women aged 50-69 years
- Methods
- double-blind, randomized, placebo-controlled study; Cognitrax test battery; evaluations before intervention, after a single dose, and after 12 weeks of regular intake
- Blinding
- Double-blind
- Duration
- 12 weeks
- Funding
- Unclear
l-theanine (γ-glutamylethylamide), an amino acid in green tea, has been shown to affect brain functions by relieving stress disorders, improving mood, and maintaining normal sleep. However, the cognitive functions for which theanine is effective are unclear. This study aimed to clarify which cognitive functions are positively affected by intake of l-theanine. A double-blind, randomized, placebo-controlled study was conducted. The subjects were Japanese men and women aged 50-69 years. Mini Mental State Examination-Japanese version score was 24 or higher. Cognitrax was used as a test battery for cognitive function. Evaluations were performed before the intervention, after a single dose of l-theanine, and after 12 weeks of regular intake. The single dose of l-theanine reduced the reaction time to attention tasks (Stroop test, Part 1), and it increased the number of correct answers and decreased the number of omission errors in working memory tasks (4-Part continuous performance test, Part 4). In conclusion, our study indicated that l-theanine may contribute to improving attention, thus enhancing working memory and executive functions. Clinical Trial No.: UMIN000033812.
Research Insights
The single dose of l-theanine reduced the reaction time to attention tasks (Stroop test, Part 1)
- Effect
- Beneficial
- Effect size
- Small
- Dose
- single dose
it increased the number of correct answers and decreased the number of omission errors in working memory tasks (4-Part continuous performance test, Part 4)
- Effect
- Beneficial
- Effect size
- Small
- Dose
- single dose
it increased the number of correct answers ... in working memory tasks (4-Part continuous performance test, Part 4)
- Effect
- Beneficial
- Effect size
- Small
- Dose
- single dose (exact dose not specified)
it increased the number of correct answers and decreased the number of omission errors in working memory tasks (4-Part continuous performance test, Part 4)
- Effect
- Beneficial
- Effect size
- Small
- Dose
- single dose (exact dose not specified)
The single dose of l-theanine reduced the reaction time to attention tasks (Stroop test, Part 1)
- Effect
- Beneficial
- Effect size
- Small
- Dose
- single dose (exact dose not specified)