The Science Behind Essential Oils
Essential oils have been used for centuries to treat common ailments, soothe symptoms and even to heal wounds. The use of essential oils and herbs as medicines were often the domain of sages, magis and herbalists. In recent times, the popularity of essential oils for self treating or self help has grown exponentially. The uses of essential oils are commonly based on what the plant is used for traditionally by native communities.
The science behind the use of essential oils is still playing catch up. One of the difficulties in using evidence based scientific trials to assess a naturally occurring substance is the variability of the substance in nature. It would be much easier for example to compare studies done using an isolate of lavender or a chemical compound rather than a pure lavender essential oil as the chemical composition of lavender in nature varies.
It is also tricky to pin down the result of a study to one chemical constituent in the lavender essential oil as the therapeutic benefit of the oil is not down to one chemical component. However, despite the difficulties, there are numerous studies that have proven significant benefit through the use of essential oils to relieve stress, reduce inflammation, heal wounds and as antibacterials and antifungals.
Take Peppermint oil for example, which has been used for centuries to treat gastrointestinal problems. Reviews of studies have found that taking peppermint oil capsules may ease the symptoms of irritable bowel syndrome (1). A small pilot study also found that peppermint oil helped ease discomfort in these patients, likely because the compounds helped to relax smooth muscles in the lower oesophagus (2).
Another common essential oil, tea tree oil is purported to have anti-microbial and anti-inflammatory properties and is an effective treatment for mild to moderate acne (3). The indigenous Bundjalung people of eastern Australia are believed to have used tea trees as a traditional medicine for many years in a variety of ways including inhaling the oil from the crushed leaves to treat coughs and colds, applying the leaves on wounds as a poultice as well as brewing an infusion of the leaves to make a tea for treatment of sore throats or applying on the skin for minor wounds, abrasions and insect bites. Another study (4) found tea tree oil was better than placebos, and just as effective as benzoyl peroxide in treating pimples. Other studies (5) suggest tea tree oil may be helpful for fungus such as athletes foot and nail fungal growth.
So, how do essential oils work and how does the body utilise these oils? Essential oils are most commonly inhaled or used topically.
The proposed mechanism of action of inhalation begins with the absorption of these volatile molecules through the nasal mucosa. These scent molecules are then transformed into chemical signals, which travel to the olfactory bulb and then other parts of the limbic system of the brain and the cerebral cortex and the olfactory sensory centre at the base of the brain. They then interact with the neuropsychological framework to produce characteristic physiological and psychological effects on target tissues (6).
Gerhard Buchbauer, a professor of pharmaceutical chemistry at the University of Vienna in Austria, who has researched and written about the chemical compounds used in aromatherapy says that when inhaled, "the absorption of essential oils by the nose is as fast as an intravenous injection. In comparison, the absorption of essential oils through the skin is slower, because some of their chemical compounds need to pass through the fat layers under the skin and may even get stored there ".
Many studies have demonstrated the health benefits of essential both in animals and humans. These studies have consistently shown that essential oils can produce specific effects on human neuropsychological and autonomic function, suggesting that essential oils have therapeutic effects on human health. Whilst we wait for science to catch up, let’s not put aside these wonderful gifts of nature and instead use them respectfully and responsibly to aid us in our quest for wellness.
Article by: Dr. Carolyn Goh
Integrated Health Consultant,
BEng., MSc., PhD (DIC)., MBBS