Acute effects of essential oil blend containing phlai oil on mood among healthy male volunteers: Randomized controlled trial.

Background Essential oil blend (ESOB) containing Zingiber montanum or Phlai and Zingiber tenuiscapus oils as the major components has high levels of terpenes such as sabinene, terpinene, terpinolene, and terpine-4-ol. Phlai is well known for its analgesic property, but its effects on mood remain unclear. This study aimed to investigate the acute effects of inhaling the ESOB containing phlai essential oils on mood and stress among healthy volunteers. Methods A prospective, randomized, double-blinded, controlled trial pilot study was conducted among 38 healthy male volunteers; 19 in the ESOB containing phlai oil group and 19 in the control group, which used olive oil. One single inhalation was provided continuously for 15 min via hot steam. Mood status was assessed pre- and post-intervention using the Visual Analog Scales for Mood, Anxiety, Stress and Alertness (MASA). Rorschach tests, in a modified analysis, were also employed. One-way ANCOVA was used to determine statistical differences of the mood test results between ESOB containing phlai oil and olive oil. Results Mean age of the participants was 22.11 (SD 2.1) years. Both ESOB containing phlai oil and olive oil increased the post-test scores of positive mood and reduced the scores of negative mood. However, no difference was observed regarding the mood test scores between groups, except concerning the Rorschach stress test (F (1,38)=6.486, p=0.015). The variance of change, explained by the model (R square), was 32.8%, while the adjusted R-squared was 0.290. Conclusions Single inhalation aromatherapy using ESOB containing phlai oil or olive oil showed an immediate improvement of mood states among healthy young male volunteers by easing the negative emotions and enhancing positive emotions, especially feelings of pleasure and contentment. Natural blend of phlai essential oils was more efficacious than olive oil in reducing emotional stress.