Abstract
We investigated the ability of sweeteners to reduce stress using two psychophysiological indices: skin conductance level (SCL) and heart rate (HR). Ten undergraduate students participated in this study. After the exposure to stress by performing the Uchida-Kraepelin Performance Test for 5 min and a mental calculation for 3 min, the participants consumed various sweeteners containing starch paste only (control group), sugar (sugar group), erythritol (erythritol group), and saccharin (saccharin group) additives for 1 min. Then, they were asked to relax by sitting still in a chair with open eyes for 10 min followed by closed eyes for an additional 3 min. Based on the Russell and Lanius model of the affective quality, only sugar among the three sweeteners exhibited high stress-reducing activity. These results indicate that sweet tastes do not have stress-reducing activity; however, sugar may have the specific function to reduce the stress. The exact mechanism of sugar's stress-reducing activity is unclear; however, a possible explanation is that glucose derived from sugar stimulates the transportation of tryptophan into the brain, which is a raw material of serotonin with a stress-reducing activity. In addition, sugar stimulates the reward system in the brain, which secretes endorphins with stress-reducing activity.
