Well sure he is just advertising his product. Though there is legitimate scientific evidence behind L-theanine inducing a relaxed and alert state of mind.  Juneja LR, Chu D, Okubo T, et al. L-theanine--a unique amino acid of green tea and its relaxation effect in humans. Food Sci Tech 1999; 10:199-204. Sakato Y. The chemical constituents of tea: III. A new amide theanine. Nippon Nogeikagaku Kaishi 1949;23:262-267. Unno T, Suzuki Y, Kakuda T, et al. Metabolism of theanine, a gamma-glutamylethylamide, in rats. J Agric Food Chem 1999;47:1593-1596. Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T. Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res 1998;23:667-673. Yokogoshi H, Mochizuki M, Saitoh K. Theanine-induced reduction of brain serotonin concentration in rats. Biosci Biotechnol Biochem 1998;62:816-817. Ito K, Nagato Y, Aoi N, et al. Effects of L-theanine on the release of alpha-brain waves in human volunteers. Nippon Nogeikagaku Kaishi 1998;72:153-157. Sadzuka Y, Sugiyama T, Suzuki T, Sonobe T. Enhancement of the activity of doxorubicin by inhibition of glutamate transporter.  Sugiyama T, Sadzuka Y. Theanine, a specific glutamate derivative in green tea, reduces the adverse reactions of doxorubicin by changing the glutathione level. Cancer Lett 2004;212:177-184. Yokozawa T, Dong E. Influence of green tea and its three major components upon low-density lipoprotein oxidation. Exp Toxicol Pathol 1997;49:329-335. Kakuda T, Nozawa A, Unno T, et al. Inhibiting effects of theanine on caffeine stimulation evaluated by EEG in the rat. Biosci Biotechnol Biochem 2000;64:287-293. Yokogoshi H, Kobayashi M. Hypotensive effect of gamma-glutamylmethylamide in spontaneously hypertensive rats. Life Sci 1998;62:1065-1068. Yokogoshi H, Kato Y, Sagesaka YM, et al. Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci Biotechnol Biochem 1995;59:615-618. So I mean, just drink more green tea and you're good.