Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial
Hidese S, Ogawa S, Ota M, Ishida I, Yasukawa Z, Ozeki M, Kunugi H
Published in Nutrients
Abstract
Clinical study on L-theanine effects on anxiety and cognitive performance
Methodology
Randomised, placebo-controlled, four-week crossover trial of L-theanine 200 mg/day in healthy adults without major psychiatric illness; outcomes included the Self-Rating Depression Scale, State-Trait Anxiety Inventory, Pittsburgh Sleep Quality Index and a cognitive battery.
Key Findings
Stress-related symptom scores (depression, anxiety-trait and sleep disturbance measures) decreased significantly after L-theanine compared with placebo. Verbal fluency and executive function scores improved, with the executive function gains driven largely by participants who had lower baseline performance. No adverse effects were reported.
Conclusions
Four weeks of 200 mg/day L-theanine reduced stress-related symptoms and modestly improved verbal fluency and executive function in healthy adults.
Limitations
Very small single-centre sample (n=30) of healthy Japanese adults; short four-week arms; multiple cognitive and mood outcomes tested without strict correction for multiple comparisons; the study received support from a manufacturer of the test material.
Supplements Studied
L-theanine shows benefits for anxiety and cognitive performance in controlled settings.
Outcomes Measured
L-theanine supports anxiety reduction and cognitive performance.
Stress-related symptom scores (depression, anxiety-trait and sleep disturbance measures) decreased significantly after L-theanine compared with placebo. Verbal fluency and executive function scores improved, with the executive function gains driven largely by participants who had lower baseline performance. No adverse effects were reported.
Stress-related symptom scores (depression, anxiety-trait and sleep disturbance measures) decreased significantly after L-theanine compared with placebo. Verbal fluency and executive function scores improved, with the executive function gains driven largely by participants who had lower baseline performance. No adverse effects were reported.
Related Health Concerns
Study Details
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Disclosures
Funding
Supported by Taiyo Kagaku Co., Ltd. (supplier of the L-theanine test material); two co-authors were company employees
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