Theanine is an amino acid commonly found in Green Tea. It is commonly taken as a supplement for its nootropic benefits.


  • Improves learning and memory [10][8][9][12]
  • Reduces mental and physical stress, improves mood [7]
  • Cognitive enhancer and neuroprotectant [10][12][8][9]
  • Reduces time to fall asleep and decreases number of nighttime awakenings [5]

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What Is Theanine?

Theanine is an amino acid found in some plants including the basidiomycete mushroom and green tea. This nootropic is known to be a stress reliever and relaxant that also carries a number of nootropic properties. In 1964 theanine was approved by the Japanese Ministry of Health and Welfare for universal consumption. It is currently available in the United States as a dietary supplement and is confirmed by the FDA for being “Generally recognized as safe” [4]

Certain beverage manufacturers have begun to manufacture drinks containing thiamine and are currently marketing them as focus and concentration aids. [18] Other manufacturers are marketing them for their ability to help people relax. [14]

Theanine Dosage Information

Even though there is no standard dose for thiamine, many sources indicate a dose of 200-300mg should be taken as needed. Other people have found that they must take as much as 500mg at a time to notice an effect. I recommend you start with a 200mg dose and work your way up as needed.  It will take 30-60 minutes for the dose to take effect and may last from 3-4 hours.

How Does Theanine Work?

Theanine is able to cross the blood-brain barrier. [3][6] Once it crosses this barrier it acts on the brain in a number of ways giving it many nootropic properties:

  • Acts as an analog to glutamine and glutamate [3]
  • Significantly increased levels of serotonin and dopamine in the brain [3][10]
  • Increases levels of the inhibitory transmitter GABA [10]
  • Promotes alpha wave production in the brain. [6] Alpha waves play an important role in coordination and communication within the brain. [1]

Safety and Side Effects of Theanine

Theanine is regarded as being “generally recognized as safe” by the FDA. In addition, there are no observed side effects associated with theanine since its widespread use starting in 1964. [4][2]

Taking theanine with medications for high blood pressure may cause your blood pressure to drop too low. Theanine may also decrease the effectiveness of certain stimulant medications. [2]

Theanine FAQ

Below are some of the most commonly asked questions about Theanine.

Should I Use Theanine?

Theanine is a proven nootropic that has many powerful effects when taken with caffeine. Not only that, but it has absolutely zero observed side effects over five decades of use. It improves a variety of cognitive functions, helps relieve stress, and acts as a neuroprotectant. Even if you don’t plan on starting an entire nootropic regimen you should consider purchasing theanine.

There is no downside to theanine in terms of safety or side effects but there is a huge potential upside.  Taking a single dose in the morning with a cup of coffee could be the key to starting off your work day relaxed, focused, and more productive.

Does Theanine Possess Synergy With Other Nootropics?

Theanine works in synergy with caffeine to improve cognition and mood. Studies have shown that taking caffeine and theanine lets to a faster numeric working memory, faster digit vigilance reaction time, improved information processing, less mental fatigue, faster reaction time, and improved verbal skills. Increased attentiveness was also observed for up to 3 hours.[8][9]

What Are Some Notable Theanine Studies?

A couple of studies have been conducted to observe the synergistic relationship between theanine and caffeine. One study subjected volunteers to difficult tests over the course of three days. Each day the volunteers were given either a placebo, 100 mg of theanine, 60 mg of caffeine, or both. Participants’ accuracy on the tests was slightly higher when they received either the theanine or caffeine over the placebo. However, the participants who received the theanine-caffeine combination had significantly higher accuracy and reported being much more attentive. The benefit from this combination lasted up to 3 hours. [9]

 Another study conducted in 2007 examined theanine’s effect on physiological and psychological stressors. The study gave participants either a theanine or placebo dose as the start of an examination or halfway through. The experiment used strict time constraints and mental arithmetic tasks as stressors. Subjects which received the theanine dose showed a reduction in heart rate and salivary immunoglubin when compared to the placebo group. [7]
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Cited Studies

1.  Palva, S. and Palva, J.M., New vistas for a-frequency band oscillations, Trends Neurosci. (2007), doi:10.1016/j.tins.2007.02.001


3.  Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T (1998). “Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats”. Neurochem Res 23 (5): 667–73. doi:10.1023/A:1022490806093. PMID 9566605.

4.  “FDA confirms GRAS status of Suntheanine”. March 22, 2007.


6. Gomez-Ramirez M; Higgins, BA; Rycroft, JA; Owen, GN; Mahoney, J; Shpaner, M; Foxe, JJ (2007). “The Deployment of Intersensory Selective Attention: A High-density Electrical Mapping Study of the Effects of Theanine”. Clin Neuropharmacol 30 (1): 25–38. doi:10.1097/01.WNF.0000240940.13876.17. PMID 17272967.

7.  Kimura K, Ozeki M, Juneja L, Ohira H (2007). “L-Theanine reduces psychological and physiological stress responses”. Biol Psychol 74 (1): 39–45. doi:10.1016/j.biopsycho.2006.06.006. PMID 16930802.

8. Haskell CF, Kennedy DO, Milne AL, Wesnes KA, Scholey AB (2008). “The effects of l-theanine, caffeine and their combination on cognition and mood”. Biol Psychol 77 (2): 113–22. doi:10.1016/j.biopsycho.2007.09.008. PMID 18006208.

9. ” John J. Foxe of the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, N.Y

10. Nathan P, Lu K, Gray M, Oliver C (2006). “The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent”. J Herb Pharmacother 6 (2): 21–30. doi:10.1300/J157v06n02_02. PMID 17182482.

12. Egashira N, Ishigami N, Pu F, et al. (2008). “Theanine prevents memory impairment induced by repeated cerebral ischemia in rats”. Phytother Res 22 (1): 65–8. doi:10.1002/ptr.2261. PMID 17705146.

13.  Roan, Shari (May 17, 2009). “L-theanine: New drinks promise focus, but more research attention needed”. Chicago Tribune.,0,2196283.story.

14.  Egashira N, Ishigami N, Pu F, et al., L-Theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8-week, randomized, double-blind, placebo-controlled, 2-center study, J Clin Psychiatry 2010;71:1-9., Stanley Research,