Like caffeine, L-theanine is a naturally occuring, physicologically active compound in tea. In fact, because this non-protein amino acid is found almost exclusively in tea, L-theanine is one more positive aspect of tea drinking. L-theanine has been shown to reduce mental and physical stress by stimulating the brain area related to increased relaxation and inhibiting activity in the part of the brain that has to do with anxiety. Prelimiary research suggests that L-theanine may also:

- strengthen the immune system's ability to fight bacteria and viruses

- improve cognitive performance and enhance concentration

- mitigate the effects of large doses of caffeine

- soothe nervousness

- lower blood pressure

*information about L-theanine taken from Specialty Tea Institute Level 3 Professional Certification Program, 2012