Affiliations: Department of Research and Development, Pharma Foods
International Co. Ltd., Kyoto, Japan | Department of Food and Nutrition, Kyoto Women's
University, Kyoto, Japan | Food and Nutritional Sciences Department, University
of Shizuoka, Shizuoka 422-8526, Japan
Note: [] Address for correspondence: Adham M. Abdou, Department of
Research and Development, Pharma Foods International Co. Ltd., Kyoto 601-8357,
Japan. Tel.: +81 75 693 8607; Fax: +81 75 693 8608; E-mail:
[email protected]
Abstract: The effect of orally administrated γ-Aminobutyric acid (GABA)
on relaxation and immunity during stress has been investigated in humans. Two
studies were conducted. The first evaluated the effect of GABA intake by 13
subjects on their brain waves. Electroencephalograms (EEG) were obtained after
3 tests on each volunteer as follows: intake only water, GABA, or L-theanine.
After 60 minutes of administration, GABA significantly increases alpha waves
and decreases beta waves compared to water or L-theanine. These findings denote
that GABA not only induces relaxation but also reduces anxiety. The second
study was conducted to see the role of relaxant and anxiolytic effects of GABA
intake on immunity in stressed volunteers. Eight acrophobic subjects were
divided into 2 groups (placebo and GABA). All subjects were crossing a
suspended bridge as a stressful stimulus. Immunoglobulin A (IgA) levels in
their saliva were monitored during bridge crossing. Placebo group showed marked
decrease of their IgA levels, while GABA group showed significantly higher
levels. In conclusion, GABA could work effectively as a natural relaxant and
its effects could be seen within 1 hour of its administration to induce
relaxation and diminish anxiety. Moreover, GABA administration could enhance
immunity under stress conditions.
Keywords: γ-Aminobutyric acid, brain waves, relaxation, stress, immunity, IgA
Journal: BioFactors, vol. 26, no. 3, pp. 201-208, 2006
