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.