L-Theanine Information | Theanine

Green Tea Plant

Green Tea Plant

L-Theanine is a non-essential amino acid and glutamic acid analog and becoming an increasingly popular supplement due to some of its unique and almost amazing properties. L-Theanine can cross the blood brain barrier and hence has psychoactive properties and is found in carmellia sinesis, the tea plant. Green tea is felt to have the greatest concentration of L-Theanine.

L-Theanine can improve mood, reduce stress and help focus and particularly when working with caffeine. Moreover, individuals taking Theanine also showed improved alpha wave activity, the activity present when you are alert but not stressed and for most people the most desirable awake state. Unlike many supplements where research is still in its infancy there is a large base of clinical trials done by the Japanese to indicate that Theanine is not only effective but also safe. Japan approved Theanine as a universally safe supplement as early as 1964 and permitted unrestricted amounts in all foods except those for infants.

While Theanine is widely touted as a mind relaxant, and for good reason, it also has some other very attractive properties. Theanine has been found to increase dopamine in humans. Dopamine is the naturally occurring chemical in the brain, which is released during pleasant activities such as eating, sex and for some…chocolate. Dopamine produces a sense of well being.

Additional research indicates even more L-Theanine benefits including that it plays a role in helping reduce cholesterol and that Theanine also may improve the efficacy of cancer treatments by decreasing the amount of cancer drug in healthy cells while focusing the drug on cancerous cells. The calming benefits of L-Theanine were also stressed in this study. Rats fed a high Theanine diet also showed a significantly lower body weight, blood plasma fat and overall body fat accumulation.
There appear to be many L-Theanine benefits and not many negative L-Theanine side effects.  However, as with any supplement there are some interactions with medications that might be significant to note. Theanine is known to reduce blood pressure and if taking Theanine supplements with blood pressure medication the potential exists to reduce blood pressure too far. Medically prescribed stimulants may interact with L-Theanine and reduce the effectiveness of the prescription. Although no case studies have been done specifically nor is there any indication it may prove harmful, it is worth noting when considering L-Theanine supplements.

The exact safe or “recommended dosage for an L-Theanine supplement is perhaps the most difficult to effectively guess. The scientific community has been unable to come up with any indication that there is an “unsafe” level of Theanine. As with any supplement, it is always best to check with a medical professional before using the supplement in the case of children, pregnant women or individuals with severe health issues.
Many studies had individuals consuming as much as 200 mg of L-Theanine a day although some limited the amounts to 50 – 100 mg per day. It is wisest to follow label directions and consult with a physician if unsure of the appropriate dosage for a specific individual. L-Theanine supplement can be obtained in capsule or tablet form.


  1. Murakami, S. Biosci Biotechnol Biochem. April 23.; 73(4):817-21. 2009
  2. Sadzuka Y, et al. Toxicol Lett. 2000 Apr 3;114(1-3):155-62
  3. Desai MJ, Gill MS, Hsu WH, Armstrong DW. Chirality 17:154-162, March 2005
  4. Timmcke, J. The FASEB journal. 2008
  5. Ueda T. et al. Journal of JSPOG Vol. 6, No. 2, pp 234-239, Dec 2001