L-テアニンのヒトの脳波に及ぼす影響  [in Japanese] Effects of L-Theanine on the Release of α-Brain Waves in Human Volunteers  [in Japanese]

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L-テアニンは緑茶の葉中および抽出液中に含まれているアミノ酸の一種で,カフェインによる興奮を抑制することが知られている.また,ラットへのL-テアニンの経口投与により,脳内のセロトニンが減少し,カテコールアミンの増加ずることが知られている. L-テアニンは動物実験で安全なことがすでに確認されている.<br> 筆者らはL-テアニン服用による脳波への影響について検討した結果,リラックスをもたらすことを確認した. L-テアニンの影響を不安程度の異なる精神状態で調べるため, MAS法に従って段階I(高不安域群)の4名と段階V(低不安域群)の4名の計8名の女子学生を被験者に選定した.<br> その結果, L-テアニン200mgを含む水100ml服用によって後頭部・頭頂部にα波の出現が認められた.α波出現は服用後40分後に観測され,少なくとも2時間は持続すると考えられる.α波の出現によるリラックス作用は,段階Vの低不安域群より段階Iの高不安域群の方が優れていた. L-テアニン服用後,被験者は眠気を感じず,十分なリラックスを感じた.また,指先が暖かくなったとの体感を感じた被験者もいた.<br> 今回の研究により, L-テアニンは新しいタイプの添加物として食品や飲料に応用される可能性が示唆された.今後はさまざまなL-テアニン含有食品についての効果を検討するつもりである.

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


  • Nippon Nōgeikagaku Kaishi

    Nippon Nōgeikagaku Kaishi 72(2), 153-157, 1998-02-01

    Japan Society for Bioscience, Biotechnology, and Agrochemistry

References:  24

Cited by:  5


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