L-Theanine is an interesting substance. It is an amino acid found in tea.

Green tea contains both caffeine and L-Theanine while coffee contains caffeine, but no L-Theanine. That’s why coffee and green tea don’t affect us exactly the same way, because L-Theanine makes us feel calm and relaxed and at the same time focused.

L-theanine has been researched for the effects on anxiety and psychological stress. Studies suggest that L-theanine at daily doses ranging from 200 to 400 mg per day for up to 8 weeks reduce anxiety and stress levels (Sakamoto FL, et al., 2019).


This study showed that L-Theanine intake resulted in a reduction of the heart rate and salivary immunoglobulin A (s-IgA) responses when exposed an acute stress task compared to the placebo control. Analyses of the heart rate variability indicated that these results were likely caused by changes in reaction of the sympathetic nervous system (Kimura K, et al., 2007).

Research has verified that enough good quality sleep is very important if we want to stay healthy.

200 mg of L-theanine before bed has been found to improve sleep quality because it causes relaxation and reduce anxiety (Rao TP, et al., 2015).

No adverse effects have been noticed for L-theanine even with a dose of 2000 mg per kg of body weight per day.


Kimura K, Ozeki M, Juneja LR, Ohira H.L-Theanine reduces psychological and physiological stress responses, Biol Psychol. 2007 Jan;74(1):39-45.

Lopes Sakamoto F, Metzker Pereira Ribeiro R, Amador Bueno A, Oliveira Santos H. Psychotropic effects of L-theanine and its clinical properties: From the management of anxiety and stress to a potential use in schizophrenia. Pharmacol Res. 2019 Sep;147:104395.

Rao TP, Ozeki M, Juneja LR. In Search of a Safe Natural Sleep Aid. J Am Coll Nutr. 2015;34(5):436-47.


  • L-Theanine is an amino acid found in tea and is one of the reasons for the beneficial effects of green tea.
  • Research has shown that daily doses ranging from 200 to 400 mg of L-Theanine produced anti-stress effects
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  • Category: News
  • Author: Didrik Sopler, Ph.D., L.Ac.
  • Published: 2020-09-11
  • Comments: 0
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