What is L-theanine and is there a health benefit?
L-theanine, an amino acid found in tea plants, is responsible for the unique flavor of green tea. This compound is said to promote relaxation and modify the stimulating effects of the caffeine present in green tea. Some research has suggested that L-theanine has calming effects. In one study, young women were given either water, 50 mg of L-theanine or 200 mg of L-theanine once a week. Afterward, their brain waves were measured. Those who received the highest dose (200 mg) produced more alpha waves, an indication of increased relaxation, about 40 minutes after getting the L-theanine. Results of this study were published in the June 1999 issue of Trends in Food Science & Technology. However, more research will be needed to confirm the findings. Other studies, including animal studies, have suggested that L-theanine has an anticancer effect, may enhance learning in animals and lowers blood pressure in hypertensive rats. But none of these benefits has been demonstrated in humans, at least
