L-Theanine in cancer prevention and treatment Asians have a lower incidence of cardiovascular disease and cancer despite high rates of cigarette smoking. The reason for this protection may be a high consumption of tea, particularly green tea. The average of 1.2 liters of green tea consumed daily by many people in Asia offers the anti-oxidant protection from the polyphenolic compounds in green tea. A review of more than 100 experimental and clinical studies on green tea has confirmed the anticancer property of this famous drink. L-theanine is a unique free form amino acid found only in the tea plant and in the mushrooms Xerocomus badius and certain species of genus Camellia, C. japonica and C. sasanqua. Initial interest in theanine arose due to the seemingly paradoxical calming effect of the caffeine-containing drink. Theanine is a naturally occurring amino acid present at significant levels in tea leaves and is the component responsible for this relaxing effect. Theanine has been found to alter glutamate transport and increase GABA levels. L-theanine enhanced the antitumor activities of doxorubicin, anthracyclines, cisplatin and irinotecan. Consequently, the modulating effect of theanine on the efficacy of antitumor agents is expected to be applicable in clinical cancer chemotherapy. L-theanine may be used as an effective chemopreventive agent for cancer.

[Fifth AACR International Conference on Frontiers in Cancer Prevention Research, Nov 12-15, 2006]