EFFECTS OF L-THEANINE ON THE RELEASE OF A LPHA-BRAIN WAVES IN HUMAN VOLUNTEERS

L-Theanine is an amino acid found in green tea leaf and in its infusio n, and is known to control excitement caused by caffeine. It is also k nown that the oral administration of L-theanine to rats results in a d ecrease of serotonin and increase of catecholamines in their brain. L- Theanine has been confirmed to be safe in animal experiments. We found recently that oral intake of L-theanine caused a feeling of relaxatio n among the human volunteers examined. These observations led us to do experiments on the effects of administration of L-theanine on the bra in electric waves. Eight female university students were selected as v olunteers. Four of them were ranked to be Grade I(the highest anxiety) and the remaining four, Grade V (the lowest anxiety) in an investigat ion done by the manifest anxiety scale method. A dose of oral administ ration of 200 mg of L-theanine dissolved in 100 ml of water resulted i n the generation of a-electric waves in the occipital and parietal reg ions of the brains of the subjects. The emission intensity of a-brain waves (integrated as a function of investigation times and area) was s ignificantly greater in the group of Grade I than that of Grade V. The se results indicate the possibility for L-theanine to be applied to fo ods and beverages as a new type of functional food ingredient for its relaxation effect.