Evaluating the effect of aromatherapy on a stress marker in healthy subjects

Chemotherapy is important for cancer treatment, but patients' physical and mental stress may lead to unfavorable pain control, an increase in the risk of relapse, and a reduction in the quality of life (QOL). Recently, aromatherapy has been performed in addition to palliative care in many countries, such as Japan and the United States, but scientific evidence remains insufficient. To investigate the usefulness of aromatherapy as complementary and alternative medicine, we evaluated its influence on the immune and autonomic nervous systems.

We instructed healthy volunteers to inhale aroma oil at bedtime for 6 weeks, and measured changes in the salivary level of secretory immunoglobulin A (s-IgA). Furthermore, blood was collected in addition to saliva in some healthy volunteers, and the blood level of noradrenaline (NA) was measured to examine its relationship to changes in the salivary s-IgA level.

Aromatherapy with lavender and grapefruit oils significantly increased the salivary s-IgA level: lavender oil increased 3.5-fold (p = 0.03), and grapefruit oil increased 2.55-fold (p = 0.04). On lavender oil inhalation, there was a weak, positive correlation between changes in the salivary s-IgA level and those in the blood NA level (R² = 0.24).

The results showed that aromatherapy with lavender and grapefruit oils reduced stress by acting on the immune and autonomic nervous systems in healthy volunteers. In the future, its clinical usefulness must be investigated through similar examination in patients in whom the stress level may be high.