Authors: Shinsuke Hidese, Shintaro Ogawa, Miho Ota, Ikki Ishida, Zenta Yasukawa, Makoto Ozeki, Hiroshi Kunugi
Institutions: National Center of Neurology and Psychiatry; Taiyo Kagaku Co. Ltd.
Source: Nutrients, October 3 2019; Volume 11, Issue 10, Article 2362
Objective: This trial tested whether taking 200 mg of L-theanine daily for four weeks could ease stress symptoms and boost thinking skills in healthy adults.
Methods: Thirty volunteers (nine men, 21 women; average age 48) with no major psychiatric issues received either L-theanine or a placebo in a randomized, double-blind crossover design. After each four-week period, participants completed questionnaires on depression, anxiety, and sleep quality, and took tests of verbal fluency and executive function.
Results: L-theanine reduced depression and anxiety symptoms. It improved sleep by helping people fall asleep faster and stay asleep longer. The supplement also boosted verbal fluency and executive function. The biggest gains in word tasks appeared in those with lower starting tests scores.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
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