Effect of GABA Intake on Autonomic Nervous Activity After Mild Mental Stress: A Study of Heart Rate Variability Analysis using Wavelet Transform

Gamma-aminobutyric acid (GABA) is one of the functional foods that have good effects on human health. Although some studies reported the anti-stress effects of GABA by evaluating autonomic nervous activity via heart rate variability (HRV), no stress task was conducted during the experiments. Additionally, the HRV analysis methods used in these studies did not consider the non-stationarity and non-linearity in the HRV data. In this study, we investigated the effect of a single intake of GABA on autonomic nervous activity after mild mental stress by HRV analysis using the wavelet transform. HRV data were obtained from seven males by recording electrocardiograms before and 30, 45, and 60 min after GABA or placebo intake. As a stress task, a modified version of the Uchida- Kraepelin test was performed for 17 min starting 13 min after the intake. HRV indices were calculated using the wavelet transform. A significant decrease in the relative HF power (one of the HRV indices) was confirmed after stress in the placebo condition, but not in the GABA condition. This suggests that GABA intake may suppress the decrease in parasympathetic nervous activity that occurs after mild mental stress.