Korean J Nutr.  2003 Nov;36(9):918-923.

Effects of Theanine on the Release of Brain Alpha Wave in Adult Males

Affiliations
  • 1Department of Family Medicine, St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
  • 2Obesity Clinic, St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.

Abstract

L-theanine Is an amino acid in green tea and has been known to decrease serotonin and increase norepinephrine in rat brains, and also reported to produce mental relaxation, lower blood pressure and improve learning ability in human beings. But, few studies on these effects for human beings have been conducted so far. This study was conducted to evaluate the effect of L-theanine on the release of brain alpha waves known to be related with mental relaxation and concentration. Twenty healthy male volunteers aged 18 to 30 years without any Physical and Psychological diseases were recruited through written advertisement. Alpha power values of EEG as a surrogate marker of mental relaxation and concentration were measured in frontal and occipital regions for 40 minutes after administration of four placebo or test tablets and 20 minute resting period. The same procedure crossed over at 7-day intervals. We analyzed average alpha power values in frontal and occipital regions at 10 minute intervals. Repeated ANOVA revealed that there were significant differences of occipital alpha power values between placebo and test groups with high anxiety (p<0.05). The mean values at 20,30,40,50 and 60 minute intervals were 0.23, 024, 0.28, 0.25 and 0.34 in placebo, respectively and 0.23, 0.29, 0.40, 0.34, and 0.45 in test, respectively. But there were no significant differences of frontal and occipital alpha power values between placebo and test groups with low anxiety (p>0.05) . The results of this study suggest that L-theanine containing tablets promote the release of alpha waves related to mental relaxation and concentration in young adult males.

Keyword

theanine; green tea; alpha wave; mental relaxation

MeSH Terms

Adult*
Animals
Anxiety
Biomarkers
Blood Pressure
Brain*
Electroencephalography
Humans
Learning
Male*
Norepinephrine
Rats
Relaxation
Serotonin
Tablets
Tea
Volunteers
Young Adult
Norepinephrine
Serotonin
Tablets
Tea
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