Aromatherapy is both art and science. The science and chemistry of essential oils has led to an understanding of how they work on us both emotionally and physically. The study of the sense of smell tells us a bigger story, much deeper than emotions and mood, about how essential oils work for health and healing. Essential oils and their chemistry interact on the whole body in a complex action that can’t be understood by the chemistry alone. There is a creative piece to using essential oils. The more you use the oils and the more you learn about them, the more creative, effective, and efficient you will be at extracting their powerful healing benefits.
As you have already discovered in The Background chapter, there’s a difference between the aromatic plants used centuries ago and the essential oils used today. Ancient civilizations used different extraction methods (tinctures, macerations, unguents, or incense) to receive the benefits from the plants. An essential oil, by definition, is the highly concentrated plant’s lipid (oil) essence released through the art and skill of distillation or cold pressed from the fruit peel. Plant-based therapy has evolved from the use of the whole aromatic plant to the therapeutic benefits we have today using the very concentrated plant essence in essential oils, as well as more modern extractions, like supercritical CO2.
Plants hold their essential oils in little sacs, or vessels. Where you find those sacs and how you extract the oil depends on the plant. Methods include:
• Distillation. When the oil is called an essential oil, it means it was derived from the roots, flowers, leaves, or other parts of the plant by steam, water-steam, or water distillation.
• Expression. Also called cold pressing, this method is used for citrus rinds. It involves pressing the rind to break the sacs and separating the oil from the watery juice. These extractions are also called essential oil.
• Absolute, solvent extraction. This method is mostly used on delicate flowers that would be damaged by the heat of steam distillation. The process uses a solvent (usually hexane) to separate the essence from the plant material, resulting in the fragrant oil, or absolute. These are not called essential oils.
An Oil’s Fingerprint
Each plant is known to produce an oil with preset benefits and a typical aroma. For example, all peppermint essential oil will have a familiar mint fragrance. Nature is creative though, giving each batch of oil its own particular fingerprint, resulting from the plant’s growing location, altitude, seasonal weather, and the farming methods used. That fingerprint can result in ever-so-slight to extreme differences in the aroma and chemical structure of the oil. Overall fragrance and chemical structure of each oil are also determined by the skill and style of the distiller.
• Supercritical CO2 extraction. With this method, pressurized CO2 diffuses through the plant and extracts its essence. The aroma is much closer to the whole plant and contains therapeutic compounds that are missing from the distilled oil. The extracts may be called supercriticals or CO2 extracts and, similar to absolutes, are not called essential oils.
An oil’s benefits are determined by its complex chemical structure. We can understand some of an oil’s benefits through the chemical compounds it contains. Linalool in lavender and clary sage can ease anxiety, the limonene in citrus oils can support the liver, the eucalyptol in rosemary can clear lung congestion, and the eugenol in clove can fight infection. The action of these chemicals on cell receptors or as a trigger to the release of our own transmitter molecules through the limbic part of the brain and other complex actions has helped us to understand how essential oils work. Essential-oil interaction with human chemistry is complex and there is still a lot to learn.
Every one of the growing list of essential oils has multiple therapeutic benefits. Lavender, for example, has the potential to relax, relieve pain, and heal wounds. Bergamot can help with sleep, aid digestion, reduce anxiety, and fend off pests.
Scientific studies have shown that essential oils have pharmaceutical-like properties, making them very effective for natural homecare treatments. How essential oils work can be understood from these studies. For example, lemongrass and cinnamon kill bacteria by disrupting the cellular function in a way that makes it difficult for the bacteria to become resistant. The way helichrysum, clove, and cedarwood work to reduce inflammation and pain is by regulating the body’s inflammatory response and diminishing pain transmitters. These actions are understood in a similar way to the functions of pharmaceutical and over-the-counter medicines. The chemical synergy makes it more difficult to study essential oils in the same way as pharmaceuticals. Even if we don’t know how they work, science still supports the benefits of essential oils for holistic home use.
The Importance of Synergy
There are hundreds of chemical compounds in each oil, with a composition that may contain a dominant chemical compound or a wide mixture. For simplicity, you can understand the chemical structure of an oil as having three categories: major, minor, and trace. What’s important to understand is that the compounds work together to create the therapeutic benefits of the oil. This is called “synergy.” While scientists can study specific compounds, these individual chemicals do not tell the whole therapeutic story or demonstrate the effectiveness contained in the whole complex structure of the complete oil. Synergy and complexity are why you should always look for authentic, complete, and skillfully distilled oils.