4. Discussion
mental disorder, Anxiety, daytime disturbance
This study was conducted to confirm the effect of the single intake and repeated intake of REP hydrolysate on the subjective mood. The single intake of REP hydrolysate significantly improved the POMS 2 subscale of Tension–Anxiety (The single intake of REP hydrolysate showed a significant improvement in the POMS 2 Tension–Anxiety subscale (As a subjective mood improvement was observed in Study 1, the salivary concentration of the CgA was analyzed. The salivary CgA was selected because it reportedly reduces its concentration by anxiolytic ingredients, reflects acute psychological stress, has a relatively small daytime disturbance, and is rarely influenced by physical movement [The reason why no significant positive intervention effect of REP hydrolysate after the 4-week intake was observed might be because the duration of intervention was insufficient. As mentioned above, the animal study showed that the vagotomy treatment partially inhibited the effect of REP hydrolysate on the tail suspension test. This implies that the REP hydrolysate achieved an antidepressant-like effect through the humoral pathway, in addition to the neural pathway. For example, it is known that blood pressure is dually regulated by neural regulation and humoral regulation. Furthermore, it is controlled with neural regulation for the short term, whereas it is controlled with humoral regulation for the long term [Previous research reported that not only stressors in the past but also anticipating upcoming stressors can negatively affect the current status [Despite this study’s limitations, including the modest sample size, the POMS 2 validation confirmed only with younger population, the lack of information that could affect subjective mood states (e.g., past history of mental disorder and marriage status), the number of participants that were excluded from the salivary analysis, and no experiment-wide false detection rate evaluated, this study obtained positive results under the best conditions that could be achieved.