science essential oils

The Science of Essential Oils by Dr R.Fawcett MD

Plants have provided us with our only form of medicine for the majority of human history. We evolved with plants, and our physiology depends on the same organic molecules. Aromatic plants including herbs, trees, and spices have helped humanity to heal for thousands of years. These medicinal plants remain a mainstay of treatment in traditional medicine around the world, and there is a rapidly growing interest in the uses of essential oils in mainstream wellness practices.

Essential oils are the “essence”, or extract, of a plant’s aroma and flavour. The extraction process is unique to each plant; peppermint essential oil is steam distilled from the leaves, while lemon essential oil is cold-pressed from the peel. The quality of the essential oil depends on the environment in which the plant is grown – including the soil conditions, climate, and altitude – as well as the integrity of the extraction process. In addition to their traditional uses as plant medicines, high quality essential oils are used in food and beverages as natural flavouring.

In recent years, essential oils have increasingly attracted the interest of biomedical scientists, and a growing body of research is providing modern confirmation of the physiologic effects of aromatic plants. Each essential oil has a unique and complex natural chemistry that provides a variety of benefits for the plant: protection against environmental threats and diseases, attracting pollinators, and even plant-to-plant communication. These compounds also have a wide range of biological benefits to humans.


How Do Essential Oils Work?


A single drop of essential oil contains up to 300 different volatile compounds. When we inhale an essential oil, the aromatic molecules interact with the olfactory (smell) receptors in our nose, which then link directly to the limbic system of the brain and can have a profound effect on our emotions. Recent research has shown that we also have olfactory receptors in our skin, so we are also activating those receptors when essential oils are applied topically to the skin. Furthermore, the small molecular size of essential oil compounds and their lipid solubility allows them to freely cross cell membranes and affect the biochemistry of our cells, including antioxidant activity and inflammatory responses.

Lavender essential oil provides an example of the diversity of physiologic effects. In addition to its calming scent, studies have shown that when lavender essential oil is taken internally, it can modulate the brain’s serotonin system through its binding to NMDA receptors and serotonin transporters. Experimental research suggests that lavender may also possess antioxidant properties and support the immune function of our cells.


Essential Oils and Antibiotic Resistance


Essential oils achieve these diverse effects as a result of their molecular chemistry. The variety of essential oil compounds – known as constituents – is astonishing. They are classified by their functional groups and include esters, monoterpenes, alcohols, sesquiterpenes, and many more. Some of the compounds have yet to be identified, and only a fraction of plant species have been investigated for their potential benefits. Each drop of essential oil provides a delicate balance of constituents that act synergistically to provide an effect that is more than the sum of its parts. It is precisely this synergy that is of significant interest to medical researchers concerned with the growing crisis of antibiotic resistance.

We have acquired thousands of years of human wisdom in using aromatic plants to benefit our health; essential oils have quite rightly been described as “Medicines out of the Earth” and “Nature’s Pharmacy.” Scientific research is now deepening our understanding of the rich chemistry of essential oils and how we can most effectively harness their benefits to improve our health.

Robin Fawcett MD

To access published articles related to essential oil research, visit

Guest contributor, Dr. Robin Fawcett MD, is a General Practitioner, family physician and TEDx speaker who uses functional and lifestyle medicine, including the science of essential oils, alongside her conventional modern medicine practices. She gives us the facts and research on essential oils, how they’re extracted, their medicinal properties and how they can help us harness the powers of plants for better health.

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