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Pharmacol Res. 2019 Sep;147:104395. doi: 10.1016/j.phrs.2019.104395. Epub 2019 Aug 11.

Psychotropic effects of L-theanine and its clinical properties: From the management of anxiety and stress to a potential use in schizophrenia.

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University of Western São Paulo, Presidente Prudente, São Paulo, Brazil.
College of Health, Life and Environmental Sciences, University of Worcester, United Kingdom.
School of Medicine, Federal University of Uberlândia (UFU), Uberlandia, Minas Gerais, Brazil. Electronic address:


Anxiety disorders are highly prevalent in modern societies, and are ranked the sixth most important contributor of non-fatal negative health outcomes. L-theanine is an amino acid naturally found in green tea (Camellia sinensis) and some other plant extracts, and recent clinical studies have proposed promising adjuvant effects of L-theanine for the negative impact of anxiety and psychological stress on health. In this integrative narrative review, we aimed to appraise and further discuss the effects of L-theanine administration on anxiety disorders and psychological stress. Published data suggests that L-theanine administered at daily doses ranging from 200 to 400 mg for up to 8 weeks are safe and induce anxiolytic and anti-stress effects in acute and chronic conditions. L-theanine at doses lower and higher than these may also show promising therapeutic potential; however, a more thorough investigation through randomized double-blind placebo-controlled crossover clinical trials are necessary to elucidate its effects for longer periods, providing further insights for meta-analyses and the development of recommendation guidelines. Additionally, animal studies investigating a higher dosage, its combination with other pharmacological compounds and associated metabolic comorbidities are recommended, as cases of hepatotoxicity associated with the consumption of green tea extract have been reported.


(L)-theanine; Anxiety; Camellia sinensis; Green tea; Psychological stress; Schizophrenia


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