L-Theanine is a very popular amino acid that is found naturally in tea, many types of mushrooms, and in a number of other foods. It was first discovered in tea in 1949 and has been extensively researched ever since. L-Theanine is sold as a dietary supplement in the United States. The Food and Drug Administration (FDA) has given L-Theanine the classification GRAS (generally regarded as safe).
This supplement is widely used for its ability to reduce anxiety without producing much sedation. In fact, L-Theanine has been reported to be mildly stimulating. Taking L-Theanine with caffeine has been shown in several clinical studies to increase its effects.
What are some of the benefits of L-Theanine?
- ⇒ Reduced Stress
- ⇒ Improved Mood
- ⇒ Decreased Anxiety
- ⇒ Improvement in Cognitive Performance
- ⇒ Increased Focus
Unlike the racetams, L-Theanine has very little influence on the ionotropic glutamate receptors. It’s psychotropic effects are caused in part to its ability to increase dopamine levels in the brain. Dopamine is the “feel good” neurotransmitter in the brain that plays a large role in pleasure, motivation, goal-oriented behavior, mood, and other important functions. L-Theanine may also affect serotonin levels in the brain, but more research is necessary to confirm this.
L-Theanine is widely considered to be safe. It is found naturally in many different types of teas, mushrooms, and other foods. The FDA has classified L-Theanine as generally regarded as safe (GRAS). However, as with all supplements, you should always consult a physician before starting anything new.
The recommended dosage of L-Theanine is 150-250mg. As with all supplements, you should always start at the low end to asses tolerance and work your way up as necessary. Many people find that L-Theanine works much better when it is consumed with 100-200mg of caffeine.
 “FDA confirms GRAS status of Suntheanine”. NutraIngredients-USA.com. March 22, 2007.
 Giesbrecht, T.; Rycroft, J.A.; Rowson, M.J.; De Bruin, E.A. (2010). “The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness”. Nutritional Neuroscience 13 (6): 283–90.
 Owen, Gail N.; Parnell, Holly; De Bruin, Eveline A.; Rycroft, Jane A. (2008). “The combined effects of L-theanine and caffeine on cognitive performance and mood”.Nutritional Neuroscience 11 (4): 193–8
 Nathan, Pradeep; Lu, Kristy; Gray, M.; Oliver, C. (2006). “The Neuropharmacology of L-Theanine(N-Ethyl-L-Glutamine)”. Journal of Herbal Pharmacotherapy 6 (2): 21–30.
 Yokogoshi, Hidehiko; Mochizuki, Mikiko; Saitoh, Kotomi (1998). “Theanine-induced Reduction of Brain Serotonin Concentration in Rats”. Bioscience, Biotechnology, and Biochemistry 62 (4): 816–7