Monks have been drinking tea for thousands of years to maintain a state of “mindful alertness” during long periods of meditation. But only in the last few years have studies shed light on why tea has this effect on the mind. The two elements responsible for this are caffeine and L-theanine, and it is the combination of the two that makes tea unique from any other drink.
Spare Me the Science: What L-theanine and Caffeine can do for the Mind
- Promote a mindful state of relaxation
- Increase our ability to multi-task, and multi-task well
- Increase speed of perception
- Increase performance under stress
- Improve learning ability and concentration
- Decrease anxiety
- Reduce task-induced fatigue
L-theanine is an amino acid responsible for increasing alpha brain wave activity, which promotes relaxation. In concert with the stimulant caffeine, this allows tea to induce a feeling of increased concentration over a longer period of time, compared to caffeine alone. Some tea merchants will tell you that tea “releases” its caffeine into the body more slowly than coffee, but in actuality, the effects of caffeine are being moderated by L-theanine.
Recent studies have shown that tea “. . . taken throughout the day can significantly benefit speed of perception and more consistent levels of simple task performance. L-theanine appears to antagonize the stimulatory effects of caffeine by decreasing seratonin levels that have been artifically elevated by caffeine” . As a result, the bod sustains a feeling of alertness that cannot be obtained by the caffeine in coffee or soda.
Studies have also shown that there are added benefits to tea, besides alertness. In a paper by Eschenauer and Sweet, it was concluded that “increased alpha activity in the brain induced by L-theanine has been associated with increased creativity, increased performance under stress, and improved learning and concentration as well as decreased anxiety.”  A 2001 study suggests that the combination of L-theanine and caffeine “improves the ability to multi-task and reduces task-induced fatigue,”  which is something we can all benefit from.
L-theanine is seldom found anywhere in nature other than tea, a single species of mushroom, and guayusa which is a holly species typically processed and drunk as a tisane. It is “synthesized in the roots and concentrates in the leaves, where sunlight converts [L-theanine] to polyphenols,”  In other words, shade-grown teas like Gyokuro, a Japanese green tea, have higher concentrations of L-theanine because the amino acid is not converted into polyphenols as much as tea leaves that are exposed to full sun.
Due to the unique combination of L-theanine and caffeine found in tea, there are many reasons as to why this can be another alternative to coffee and soda, especially when looking for a jump-start to the day, or a way to maintain concentration for hours of coding and/or studying. It is best to experiment with different teas and find out how each tea affects you. A good starting point to discover different and appealing teas is the “Hacker’s Guide to Tea.“
-  Bryan, Janet. "Psychological Effects of Dietary Components of Tea: Caffeine and L-theanine." Nutrition Reviews 66.2 (2008): 82-90. Web. ↩
-  Eschenauer G, Sweet BV. Pharmacology and Therapeutic Uses of Theanine. AM J Health-Sys Ph 2006; 63-26-30. ↩
-  Giesbrecht, T., J. A. Rycroft, M. J. Rowson, and E. A. De Bruin. "The Combination of L-theanine and Caffeine Improves Cognitive Per..." Nutritional Neuroscience 13.6 (2010): 283-90. Web. ↩
-  "L-Theanine." Alternative Medicine Review 10.2 (2005): 136-37. Print. ↩