Essential oil inhalation is a holistic and economic treatment for the alleviation of anxiety. Whether this effect is of a psychological or physiological basis has been in dispute since the beginnings of ‘modern’ medicine. Many would argue that any effects felt are simply psychological, a ‘placebo’ effect, as if the individual believes the treatment will aid them it does.

Essential oils are volatile liquids composed mainly of terpenes, derived from aromatic plant material by steam distillation or mechanical expression¹. Commonly used in medicine up until the 20th century, post- 20th century they became confined to usage as preservatives and flavour enhancers. However, a group of researchers in China² has identified evidence that there may indeed be a physiological effect from the inhalation of essential oils. The scientists identified a global change in the metabolic profile of rats exposed to a prepared mixture of Lavandula angustifolia (lavender), Salvia sclarea (clary sage), Santalum album(sandlewood) and Citrus sinensis (orange fruit). The treated rats were exposed for a period of ten days to the aroma and then the behavioural effects tested by the elevated plus maze (EPM) test. The EPM test is well-documented in the testing of drugs designed for the treatment of stress-related disorders.

The metabolite profile of the rats was measured by analysing the global levels of compounds within brain tissue and urine samples, comparing the metabolic profiles of treated and untreated rats. Gas chromatography coupled to time–of–flight mass spectroscopy (GC–TOF-MS) was used to identify compound levels differentially expressed following exposure to the prepared aromas. The rats exposed to the aroma experienced weight gain and experienced a greater level of calm compared with control rats when tested. It was found that there were 50 metabolites differentially expressed in the brain tissue compared with 17 metabolites in the urine samples. There were also lower levels of neurotransmitter and carbohydrates within the brain tissue following aroma exposure compared to controls. This indicated a change in the levels of metabolites in the brain, coconcurrent with an increased level of calm. It is hoped that in the future, that this research will highlight new targets for the development of drugs aimed at the treatment of anxiety‑related disorders and that the mechanistic understanding may be further elucidated. However, further study is required to validate the findings in humans.

1. National Cancer Institute (USA), (www.cancer.gov).

2. Guoxian Xie et al, PLOS ONE, 7(9), (2012).

This story originally appeared in The Column. Click here to view that issue.