L-theanine in the adjunctive treatment of anxiety disorder

Objective: To evaluate L-theanine as an adjunctive treatment for anxiety disorder in adults. In this controlled clinical study, participants with persistent anxiety symptoms received L-theanine or comparator treatment while symptom severity, sleep quality, and global functioning were monitored over time. The intervention group showed greater reduction in anxiety scores and improved subjective calmness, with some concurrent benefit in sleep-related complaints. Effects were modest but clinically plausible, especially in participants with elevated baseline tension rather than severe psychiatric instability. Treatment was well tolerated, with few discontinuations and minimal reports of adverse effects. The results are consistent with L-theanine's proposed influence on alpha-wave activity and excitatory-inhibitory balance in the central nervous system. However, sample size, treatment duration, and blinding limitations reduce certainty, and the study does not establish equivalence to standard anxiolytic therapy. The findings support further research on L-theanine as a low-risk adjunct rather than a standalone treatment.