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Green Tea Amino Acid Reduces Stress Responses
Background: Everybody knows that too much
stress is bad for the heart, but did you know that you can ease stress and
increase relaxation by drinking green tea?
Theanine, the amino acid found in
green tea leaves that gives the tea its mellow taste, has a calming, restorative
effect on the brain. Used in Japan to ease the effects of stress and modulate
the mood, theanine works by releasing GABA (gamma amino butyric acid) in the
brain. GABA inhibits over-excitation of the brain, thus easing anxiety and
promoting relaxation.
Participants: Twelve volunteers
Where: Japan
Type of study: Double-blind
Study Methods: The volunteers underwent
four separate trials: in one, they took L-theanine at the start of the
procedure; in one, they took it midway through the procedure, and in two they
took either a placebo or nothing. Each procedure involved taking mental
arithmetic tasks, which served as acute stressors.
What happened: L-theanine intake resulted
in a reduction in the heart rate and salivary immunoglobulin (an indication of
physiological and psychological stress).
Researchers' conclusion: "... oral intake
of L-Theanine could cause anti-stress effects via the inhibition of cortical
neuron excitation."
Citation: Kimura K, Ozeki M, Juneja LR,
Ohira H. L-Theanine reduces psychological and physiological stress responses.
Biol Psychol 2007;74(1):39-45.(Click
here to read PubMed study abstract.)
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Nadine Taylor, M.S., R.D. presents
GreenTeaLibrary.com,
the most comprehensive collection of scientific information
describing the health benefits of green tea.
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