Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks

Abstract

γ-Aminobutyric acid (GABA) is a kind of amino acid contained in green tea leaves and other foods. Several reports have shown that GABA might affect brain protein synthesis, improvemany brain functions such asmemory and study capability, lower the blood pressure of spontaneously hypertensive rats, and may also have a relaxation effect in humans. However, the evidence for its mood-improving function is still not sufficient. In this study, we investigated how the oral intake of GABA influences human adults psychologically and physiologically under a condition of mental stress. Sixty-three adults (28 males, 35 females) participated in a randomized, single blind, placebo-controlled, crossoverdesigned study over two experiment days. Capsules containing 100 mg ofGABAor dextrin as a placebowere used as test samples. The results showed that EEG activities including alpha band and beta band brainwaves decreased depending on the mental stress task loads, and the condition of 30 min after GABA intake diminished this decrease compared with the placebo condition. That is to say, GABA might have alleviated the stress induced by the mental tasks. This effect also corresponded with the results of the POMS scores. © 2011 Springer-Verlag.