L-Theanine : Stress Reduction and Improved Memory


L-Theanine is a harmless and one of the most beneficial nootropics available. Most beginning nootropic users start their nootropic experience with the theanine and caffeine stack. The nootropic benefits of taking theanine with our without caffeine are many, from reduced anxiety, to increased focus and relaxation to improved learning and memory.

L-Theanine is a naturally occurring amino acid that has been shown in some studies to improve energy levels and reduces stress. Derived from tea leaves, it was first discovered as a constituent of green tea in 1949. It was approved for sale in Japan in 1964 as an additive for unlimited use in all foods, including chocolates, soft drinks, and herb teas.

Theanine is not an essential amino acide and it is not commonly found in diet. It has a structural similarity to Glutamine and both neurotransmitters that are produced from it , which are GABA and Glutamate.

Benefits and Uses of L-Theanine

L-theanine is known to promote relaxation without sedation, reduce anxiety, improve sleep quality and overall well being. All of the benefits from theanine can be arrived at via standard dosages.

Besides its anti-anxiety and stress benefits l-theanine may also have beneficial effects on the cardiovascular system and may also prevent cancer;  however, limited clinical information is available to support these claims.

The Theanine and  Caffeine Nootropic Stack

The Theanine and Caffeine nootropic stack is one of the most popular stacks among the nootropic community. It is the safest, and one of the most effective, with most who try it experiencing immediate and noticeable benefits. This combination exists naturally in nature in green tea. The two should be combined in a 2 to 1 ratio (200 mg of theanine to 100 mg of caffeine).  This combination is noted to be synergistic in promoting cognition and attention.[6]

What is Suntheanine?

Suntheanine is the trade name for Taiyo’s patented pure form of L-theanine. Suntheanine is not an extract of green tea, but rather it is produced via a patented fermentation process that mimics the natural process in green tea leaves, resulting in a 100% pure L-isomer-theanine. Suntheanine has been consumed in beverages, foods and supplements since 1994 with no indication of adverse reactions or contraindications. The GRAS Affirmation (Generally Recognized as Safe) of Suntheanine received confirmation from the US FDA in 2007 for its use in a number of food and beverage categories (GRN 000209).

You may require a lower dosage when using Suntheanine (100 mg vs 200 mg) versus regular theanine dietary supplements. [1]

How L-Theanine Works

Theanine is structurally similar to the glutamate neurotransmitter, which is responsible for sending signals between nerve cells, and under normal conditions it plays an important role in learning and memory. Theanine increases serotonin, dopamine, GABA, and glycine levels in various areas of the brain, as well as BDNF and NGF levels in certain brain areas.

Theanine is quickly crosses the brain blood barrier, and its effects are usually felt within one hour of ingestion. Once in the bloodstream, it starts off by targeting a number of different neurotransmitters. These neurotransmitters targeted are Serotonin, Dopamine, GABA, and Norepinephrine. These are all powerful brain chemicals which have a number of effects upon cognitive processes (including learning and memory), sleep and relaxation cycles, and even pleasure and the brain’s reward system. [2]

The Benefits of L-Theanine

Theanine has been studied for its potential ability to reduce mental and physical stress, improve cognition, and boost mood and cognitive performance in a synergistic manner with caffeine.[3]

Theanine has a number of different benefits for mood, cognitive function and general health. The main effects are a general feeling of relaxation and peacefulness. An overall sentiment of well-being and optimism is often the result.

Additionally, this dietary supplement increases alpha brain waves, which are associated with a relaxed but alert state of mind. Many users report feeling calm but being very aware with high levels of mental alertness and enhanced clarity and focus.[4]

Benefits include:

  • Relaxation without Sedative Effects
  • Stress reduction
  • Reduces feelings of jitteriness due to caffeine consumption
  • Increases Attention and Focus
  • Synergistic Effects on Cognition when Stacked with Caffeine
  • Shown neuroprotective effects.
  • Improves Sleep Quality

L-Theanine Side Effects

Few adverse reactions have been reported. Adverse reactions recorded in human studies using tea extracts include headache, dizziness, and GI symptoms.


Studies on test rats have shown even repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects.[5]

Theanine is sold in the United States as a dietary supplement and has been granted GRAS (generally recognized as safe) status by the Food and Drug Administration.

L-Theanine Dosage

  • L-Theanine tends to be taken in the dosage of 100-200mg usually alongside Caffeine.
  • The recommended ratio in the Theanine and Caffeine nootropic stack is two parts theanine for one part caffeine.


[1] What is Suntheanine? 

[2] L-theanine, a natural constituent in tea, and its effect on mental state. http://www.ncbi.nlm.nih.gov/pubmed/18296328

[3] Borzelleca, J.F.; Peters, D.; Hall, W. (2006). “A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats”. Food and Chemical Toxicology 44 (7): 1158–66. doi:10.1016/j.fct.2006.03.014. PMID 16759779.

[4] Jump up   Egashira, Nobuaki; Ishigami, Noriko; Pu, Fengling; Mishima, Kenichi; Iwasaki, Katsunori; Orito, Kensuke; Oishi, Ryozo; Fujiwara, Michihiro (2008). “Theanine prevents memory impairment induced by repeated cerebral ischemia in rats”. Phytotherapy Research 22 (1): 65–8. doi:10.1002/ptr.2261. PMID 17705146.

[5] Park, Sang-Ki; Jung, In-Chul; Lee, Won Kyung; Lee, Young Sun; Park, Hyoung Kook; Go, Hyo Jin; Kim, Kiseong; Lim, Nam Kyoo; et al. (2011). “A Combination of Green Tea Extract andl-Theanine Improves Memory and Attention in Subjects with Mild Cognitive Impairment: A Double-Blind Placebo-Controlled Study”. Journal of Medicinal Food 14 (4): 334–43. doi:10.1089/jmf.2009.1374. PMID 21303262.

[6] Haskell, Crystal F.; Kennedy, David O.; Milne, Anthea L.; Wesnes, Keith A.; Scholey, Andrew B. (2008). “The effects of l-theanine, caffeine and their combination on cognition and mood”. Biological Psychology 77 (2): 113–22. doi:10.1016/j.biopsycho.2007.09.008. PMID 18006208.

L-theanine. Review of Natural Products. Facts &Comparisons Online. April 2010.


    • nootropicdaily says

      I love it as well. It has definitely improved my quality of life since I started taking it. I feel more relaxed and focused with when I take it.

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