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L-Theanine is an amino acid that influences brain nerve impulses and the production of neurotransmitters, such as GABA. It is recognized as a natural anxiolytic because it can have a soothing, tranquil impact on the body and mind without causing drowsiness which is why it is frequently used to treat anxiety, hyperactivity, and sleep-related issues. L-theanine and glutamine are structurally similar, but their effects and advantages are distinct. Both are beneficial to mental health and energy levels, although theanine is more effective as a natural stress reliever.

 Many scientific research studies support the use of L-Theanine and indicate it may have some of the following benefits:

1. Improve mental health (1)
2. Reduce effect of anxiety (
3. Improve cognitive performance (
4. Neuroprotection (
5. Improve memory (

Scientific Studies Cited

1. Improvement in mental health

“Results: Our findings suggest that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments.”

Shinsuke Hidese, Shintaro Ogawa, Miho Ota, Ikki Ishida, Zenta Yasukawa, Makoto Ozeki, Hiroshi Kunugi (2019) Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial, Nutrients, 2019 Oct 3;11(10):2362, DOI: 10.3390/nu1110236


2. Improvements in anxiety

“Results: The results after the mental tasks showed that L-theanine significantly inhibited the blood-pressure increases in a high-response group, which consisted of participants whose blood pressure increased more than average by a performance of a mental task after placebo intake. Caffeine tended to have a similar but smaller inhibition of the blood-pressure increases caused by the mental tasks. The result of the Profile of Mood States after the mental tasks also showed that L-theanine reduced the Tension-Anxiety scores as compared with placebo intake.”

Ai Yoto, Mao Motoki, Sato Murao, and Hidehiko Yokogoshi (2012) Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses, Journal of Physiological Anthropology, 2012; 31(1): 28., DOI: 10.1186/1880-6805-31-28


3. Improvements in cognitive performance and alertness

“Results: The combination of moderate levels of L-theanine and caffeine significantly improved accuracy during task switching and self-reported alertness (both P < 0.01) and reduced self-reported tiredness (P < 0.05). There were no significant effects on other cognitive tasks, such as visual search, choice reaction times, or mental rotation. The present results suggest that 97 mg of L-theanine in combination with 40 mg of caffeine helps to focus attention during a demanding cognitive task.”

T Giesbrecht, J A Rycroft, M J Rowson, E A De Bruin (2010) The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness, Nutritional Neuroscience, 2010 Dec;13(6):283-90., DOI: 10.1179/147683010X12611460764840


4. Improvements in cognitive performance

“Results: The L-theanine and caffeine combination improved both speed and accuracy of performance of the attention-switching task at 60 min, and reduced susceptibility to distracting information in the memory task at both 60 min and 90 min. These results replicate previous evidence which suggests that L-theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks.”

Gail N Owen, Holly Parnell, Eveline A De Bruin, Jane A Rycroft (2008) The combined effects of L-theanine and caffeine on cognitive performance and mood, Nutritional Neuroscience, 2008 Aug;11(4):193-8., DOI: 10.1179/147683008X301513


5. Improvements in neuroprotection and memory

“Results: l-Theanine also significantly reduced oxidative protein and lipid damage and the elevation of glutathione levels in the brain. These data suggest that the positive effects of l-theanine on memory may be mediated by suppression of ERK/p38 and NF-kappaB as well as the reduction of macromolecular oxidative damage. Thus, l-theanine may be useful in the prevention and treatment of AD.”

Tae Il Kim, Yong Kyung Lee, Sang Gi Park, Im Seop Choi, Jung Ok Ban, Hyoung Kook Park, Sang-Yoon Nam, Young Won Yun, Sang Bae Han, Ki Wan Oh, Jin Tae Hong (2009) l-Theanine, an amino acid in green tea, attenuates beta-amyloid-induced cognitive dysfunction and neurotoxicity: reduction in oxidative damage and inactivation of ERK/p38 kinase and NF-kappaB pathways, Free Radical Biology & Medicine, 2009 Dec 1;47(11):1601-10., DOI: 10.1016/j.freeradbiomed.2009.09.008