Effects of the odor of milk that was fermented with lactic acid bacteria and yeast on autonomic nerve activity and mood status were investigated. The odor of fermented milk increases gastric vagal nerve activity and decreases adrenal sympathetic nerve activity in rats. Furthermore, it has been reported that the odor of fermented milk had an anxiolytic effect based on the results of an elevated plus-maze task in mice. We investigated the effects of the odor of fermented milk on humans using physiological parameters (pupillary light reaction, heart rate variability) and a questionnaire (Mood Check List-Short form 1; MCL-S.1). Results indicated that the odor of fermented milk increased parasympathetic nerve activity and decreased anxiety in humans. These results suggest that the odor of milk fermented with lactic acid bacteria and yeast has an anxiolytic effect due to the modulation of autonomic nerve activity.
