Essential oils are aromatic compounds found in many plants. In chemistry jargon, they’re considered “volatile organic compounds.” Volatility, in this case, meaning that they readily convert from a liquid to a vapor form at room temperature. In other words, what we’re smelling are tiny molecules of vaporized oil that are lighter than air, which allows them to drift into our nose and lodge in our olfactory receptors.
It’s been found that the smell of different essential oils can alter brain chemistry in ways that impacts our emotional and mental state, hence their therapeutic potential. Essential oils are also readily absorbed into the bloodstream through the skin or stomach, creating a physiological effect with potential medical applications.
NOTE: It is generally unsafe to ingest pure essential oils or apply them directly to the skin. They must first be highly diluted. Never use pure essential oils in any way other than that which is indicated on the product label. If you have any questions or concerns, it’s best to discuss with your doctor prior to use.
What is the purpose of an essential oil in nature?
Plants produce essential oils for a variety of reason: to attract pollinators, make themselves unpalatable to insects and animals, ward off disease, or even make the soil around them toxic to other plants with which they would compete for sunlight, moisture, and nutrients. Depending on their biological purpose, essential oils may be concentrated in flowers, leaves, roots, or bark.
How are essential oils extracted from plants?
There are several methods. One of the oldest, and still the most common, is steam distillation. In this method, hot steam is forced through the plant material and then collected in a condensation device that causes the vapor to return to a liquid. In ancient times, a technique called enfleurage was also used, particularly for delicate floral oils like rose: the petals were covered in animal fat, which absorbed the essential oil; alcohol was then used to as a solvent to extract the essential oils from the fat. In modern times, essential oils are often extracted in a high-pressure system using liquid carbon dioxide, or with chemical solvents, such as hexane and acetone.
Where are they produced?
The United States, India, China, France, and Brazil are the world’s top five essential oil producers. However, there are some individual oils that are typically produced in only a handful of countries, depending on where the species grows best and other factors, such as local labor costs.
For example, frankincense and myrrh oil, which both come from the bark of desert trees, are produced in the Middle Eastern and North African countries where the trees grow wild. Ylang ylang comes from the flowers of a tropical tree found in the islands of the South Pacific. Southern France traditionally produced much of the world’s rose oil, but the high cost of land and labor in this region has shifted the majority of rose oil production to Turkey and Bulgaria. Essential oils produced on a commercial scale in the United States include peppermint (Pacific Northwest), cedar (Texas), and various citrus oils (Florida).
Should I consider growing crops for essential oil production?
Probably not, unless you’re willing to do it on an industrial scale or live in a country with cheap labor – it takes enormous quantities of plant material, often picked by hand, to make a small quantity of oil, and profit margins are notoriously thin. One exception is if you are going to produce value-added products using essential oils, such as soaps and beauty products. In that case, only small quantities of oil are needed, requiring perhaps just a few acres of land. A number of lavender farms in North America have found success with this model.
Can I make my own essential oils at home?
Yes, but you will need an essential oil “still” for distillation – similar, but not quite the same, as a still for alcohol – which are not widely available. A few manufacturers offer them online, starting at about $400, or you should try watching eBay for a deal. Many of the essential oils found in stores come from common garden plants, including lavender, oregano, peppermint, basil, clary sage, lemon balm, geranium, lemongrass, rosemary, thyme, yarrow, and chamomile. Depending on the species, you may need anywhere from a single plant to a quarter-acre planting in order to produce a small vial of oil. Plant material for some oils may also be foraged from nearby forests, including Eucalyptus, spruce, cedar, cypress, fir, and pine.
As a consumer, how do I identify good quality essential oils?
Unfortunately, quality claims on essential oil products are not well-regulated, and should be treated largely as marketing material. If a pleasant fragrance is all you are after, simply use your own nose as a guide. Therapeutic grade essential oils, however (those used by aromatherapists), are virtually impossible to assess without special training and scientific equipment.
Why is it so complicated? The same species grown in different soils, at different altitudes, harvested in different ways, and extracted with different methods will produce oils with significantly different chemical compositions, some of which are much more desirable than others for therapeutic use. Reputable essential oil purveyors only sell oils that have been analyzed for optimum chemistry. Many of these companies are listed on the National Association for Holistic Aromatherapy website.
Testing also assures that the product is not contaminated with pesticide residue or other adulterants, whether from chemical solvents used in the extraction process or low-grade oil that has been used to “cut” an expensive oil to make it cheaper. For example, 10 milliliters of steam-distilled rose oil should cost about $500 – because of the enormous number of rose petals required to produce it – but 10 milliliters of rose-scented geranium oil, produced in copious quantities from the leaves of an easily grown plant, retails for around $25. Both smell nice, but have very different aromatherapy applications.