Open AccessEffects of l -Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study
Author(s) -
Yoshitake Baba,
Shun Inagaki,
Sae Nakagawa,
Toshiyuki Kobayashi,
Makoto Kobayashi,
Takanobu Takihara
Publication year - 2021
Publication title -
journal of medicinal food
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 80
eISSN - 1557-7600
pISSN - 1096-620X
DOI - 10.1089/jmf.2020.4803
Subject(s) - theanine , placebo , stroop effect , cognition , mood , affect (linguistics) , randomized controlled trial , working memory , effects of sleep deprivation on cognitive performance , medicine , executive functions , audiology , clinical psychology , psychology , psychiatry , food science , green tea , pathology , biology , alternative medicine , communication
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.