Other names for L-theanine

Theanine, 5-N-Ethyl-Glutamine, gamma-glutamylethylamide

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Background Information

Theanine is an amino acid and a glutamic acid analog that was discovered as a constituent of green tea in 1949. In 1964 theanine was approved in Japan for use in foods such as chocolates, herbal teas, and soft drinks, but not infant food. Theanine was successfully separated from gyokuro tea leaf in 1950 which has high theanine content. Since it’s discovery, theanine has been extensively studied as a psychoactive substance that has anxiolytic and cognitive enhancing effects.

Important Information

Dosage Advice

Sleep Purposes : A dose of 200mg taken 45 minutes prior to sleep would seen reasonable.

Stacking Theanine with Caffeine: We have a number of articles discussing theanine and caffeine. In general, a 1:1 or 1;2 ratio of caffeine:theanine seems optional.

Anxiolytic / Daytime Use: A dose of 100-200mg would seem effective for 4-6 hours. Onset would be 45 minutes.

Relevant Articles

  1. Good Starting Stacks For Newcomers
  2. Are Caffeine and Theanine Synergistic?
  3. Designing Your Own Stack 3 Important Guidelines

Theanine’s Method of Action

Potential Glutamate Inhibition

There’s some evidence to suggest that theanine could exert it’s effects from blocking glutamate receptors thus lowering ANS activity and reducing the stress response. (8). Research found theanine is able to bind to glutamate receptors, but at has a significantly lower affinity than glutamic acid (9).


Theanine appears to possess some GABAeric activity. In rats, an injection of theanine was found to increase cerebral GABA contcentrations by 19.8%. (10). Theanine does not appear to be a direct GABA analogue.

Alpha Wave Promotion

One of the most researched aspects of thenaine it’s ability to increase alpha brain waves. A study of 18 healthy volunteers showed 200mg of theanine was able to to enhance alpha bands, decrease heart rate and improve reaction time in the “high stress” self assessed participants (11), low stress participants remained unaffected compared to placebo. A similar study with 20 healthy male volunteers found high anxiety subjects had increased alpha waves relative to placebo, but no change was found in the low anxiety participants (12).

Alpha waves are typically associated with sedation, relaxation, attention and a calm state of mind (13). Theanine in particular appears to effect the A1 subset of alpha bands (8-10hz) (14).

L-Theanine Benefits


Theanine is known for its properties that calm the mind and help focus the brain, as well as its positive effects on anxiety. Theanine has the ability to increase relaxation without sedation, and reduce positive and psychopathology anxiety symptoms of schizophrenia with high doses [1]. In people with hyperactivity during sleep, theanine has been noted to improve sleep quality, although sleep latency and duration are not reported to be affected [2]. Theanine (5-10mM/kg injections) administered to participants of studies were able to increase hexobarbital induced sleep time by 11-21%, but not in a manner that was dose dependent [3]. Supplemental doses of theanine to promote relaxation reportedly have no sedative side effects.


Increased alpha waves, which are associated with selective attention mechanisms and mental alertness is another benefit of theanine. The altered wave functions are reported to be evidence that theanine has both attention promoting and relaxation properties. A study conducted with a supplement called LGNC-08 (60mg theanine and 360mg of green tea extract; three times daily dosing over a 16 week period) in a person with mild cognitive impairment which was based on their MMSE scores, was concluded to be associated with improved delayed recognition and immediate recall scores with no effect on visuospatial memory via the Rey-Kim test [4].

Cardiovascular Health

Theanine appears to promote nitric oxide production in endothelial cells, and is associated with the phosphorylation of eNOS Ser 1177 [5][6]. Increased nitric oxide production was found to be associated with vasodilation in the chorioallantoic membrane, which demonstrated that l-theanine administration in vitro activated eNOS, resulting in enhanced nitric oxide production and vasodilation in the artery [6].


The oral ingestion of 99% theanine did not produce toxicity in rats at 6,500 mg/kg for 2 weeks or 2,000 mg/kg over a 28 day time frame according to reports. Having 5% of a diet as theanine for 78 weeks also did not produce toxic effects. In a 13 week toxicity test in rats, a No Observable Adverse Effect Limit (NOAEL) of 4,000 mg/kg bodyweight was established, which was the highest dose tested [7].


  1. http://www.sciencedirect.com/science/article/pii/S0924224499000448
  2. http://www.ncbi.nlm.nih.gov/pubmed/22214254
  3. http://www.ncbi.nlm.nih.gov/pubmed/4397636
  4. http://www.ncbi.nlm.nih.gov/pubmed/21303262
  5. http://www.ncbi.nlm.nih.gov/pubmed/19101751
  6. http://www.ncbi.nlm.nih.gov/pubmed/22819553
  7. http://www.ncbi.nlm.nih.gov/pubmed/16759779
  8. http://www.ncbi.nlm.nih.gov/pubmed/16930802
  9. http://www.ncbi.nlm.nih.gov/pubmed/12596867
  10. http://www.ncbi.nlm.nih.gov/pubmed/4397636
  11. http://www.sciencedirect.com/science/article/pii/S1756464611000351
  12. http://www.koreamed.org/SearchBasic.php?RID=0124KJN/2003.36.9.918&DT=1
  13. http://www.ncbi.nlm.nih.gov/pubmed/1376667
  14. http://www.ncbi.nlm.nih.gov/pubmed/18296328
  15. https://www.nootropedia.com/l-theanine