Theanine is found in every part of the tea except for the fruit and contributes the major part of amino acids in tea.
Theanine is present in highest concentration in the roots of tea plants, but is absent from tea seeds in which the principal amino acid is pipecolic acid.
Theanine naturally occurs in tea nearly exclusively as L-theanine. The other one is D-theanine but present in lower concentration in tea leaves.
There are many published studies measuring these psycho-stimulant effects of caffeine, and a clear result is that caffeine compared with placebo increases alertness, reduce fatigue and sleepiness and improves performance especially ion vigilance and psychomotor.
It has been a common view that drinking green tea imparts a sense do well being and relaxation.
This may be related to the fact that after administration of L-theanine, the intracerebral gamma-amino butyric acid level, which has antioxidant activity, significantly increases in as little as 30 min.
Theanine in tea
