Reprinted Articles

Chemistry?!? Are your eyes glazed over yet? It happens…yet if you’re interested at all in the therapeutic use of essential oils, a little primer on their chemistry can be very useful. Not only will you better understand how and why essential oils work, but the great importance of using natural, high-quality oils - oils that are pure, properly distilled, AND smell nice - will be made clear. It’s not just an aromatherapy sales pitch; essential oils with exceptional bouquets have different chemical make-ups than flat or otherwise uninteresting oils. The differences can significantly affect the healing potency of therapeutic applications for you, your family and/or your clients. Much of the time, you can discern the difference of therapeutic value between two oils just by their aroma - one needn’t always have the proof of fancy, expensive machines to make an educated choice.

So what is it that makes an essential oil different than every other oil we’re familiar with? They don’t feel the same, they don’t act the same, and they certainly don’t smell the same. Essential oils and the so-called ‘fixed’ oils (you may also know them as carrier or base oils - like Sweet Almond, Apricot Kernel, Evening Primrose, etc) are distinctly different in their molecular structure. While both essential and fixed oils share common basic atomic elements of Carbon and Hydrogen, that’s really where the similarity ends. Fixed oils are made of triglyceride structures - three long chains of carbon atoms, with hydrogens bonded at various places. The length of the chains and the position and number of hydrogens define the nature of the oil; if hydrogens are bonded to every available location, the oil is ’saturated’, for example. One missing hydrogen is ‘mono-unsaturated’, more than one is ‘poly-unsaturated’. The long chains and relative consistency of the molecular structures makes fixed oils ‘oily’, and does not allow them to evaporate quickly.

Essential oils are ‘volatile’ oils - oils that DO easily evaporate. Their chains of carbon atoms to which the hydrogens attach are not as long or heavy, and are much more complex. Many essential oil structures are not really chains, but ring, or multi-ringed shapes with diverse sub-units - called ‘functional groups’ - sticking out in various directions. Like their fixed oil counterparts, essential oils are lipophillic - meaning ‘fat liking’. The fat-liking nature of both fixed and essential oils makes them easily absorbed by our bodies. Because of their typically smaller structures however, essential oils are absorbed more rapidly than fixed oils, and can easily penetrate deep into the body. Despite their plant origins, this lipophillic nature of essential oils makes their profound healing action on the human body possible.

Most of the therapeutic activity of an essential oil can be attributed to the functional groups of the individual chemicals that make up the oil. There can be over a hundred identifiable molecules in one essential oil. Each of these molecules, as mentioned earlier, is a chain or ring (or multiple-ring) structure of carbon atoms linked together with hydrogen atoms bonded to them in various configurations. Every chain or ring has a functional group attached - a functional group is defined by Salvatore Battaglia in ‘The Complete Guide to Aromatherapy’ as: “a single atom or group of atoms that…has a profound influence upon the properties of the molecule as a whole. It is often referred to as the chemically active center of the molecule”.

As you can see, essential oils are really very complex in their chemical nature. There are nearly infinite possibilities of functional group and ring or chain combinations. And ONE essential oil alone can be made up of HUNDREDS of these different molecular arrangements. Don’t worry, though! While it sounds complex, one needn’t know all the precise chemical details to use essential oils therapeutically. When selecting between varieties of an essential oil, It IS helpful to know that any particularly oil is often composed of one or more primary molecular forms, with many minor or ‘trace’ constituents, and that ALL these molecules contribute to the oil’s aroma and therapeutic action.

Many factors in an essential oil’s production affect the total number and relative amounts of individual chemicals found in the final product. These include where the plant was grown, soil and climate conditions, time of harvest, distillation equipment, plus the time, temperature and pressure of distillation. This can give you an idea as to why two varieties of the same oil can smell so different: The full, beautiful bouquet of a fine essential oil will contain a myriad of notes, telling you that all natural components are present and in balanced amounts. Poorly distilled oils may lose some of the secondary constituents during production, and adulterated or synthetic oils may not have some of the trace components at all, detectable by your nose as a flat or uninteresting aroma.

To best understand this, we’ll examine Lavender essential oil; more than fifty individual molecules have been identified in pure lavender essential oil. The aromatherapist must remember that ALL of these chemicals found in pure and natural lavender oil work together to produce a therapeutic effect. For example, the linalool molecule is antiviral and antibacterial; the linalyl acetate is emotionally calming; other major components including cineol, limonene, pinene and others are all noted for specific biologic and aromatic activity. It is the combined, balanced, synergistic action of these chemicals that make pure, high-quality lavender such a great healer. No one chemical can be singled out and used to give the same profound results as the complete pure essential oil.

So how is this synergy reflected in Lavender’s aroma? Each of these chemicals has a unique smell; some are sweet, some are camphorous, some citrusy and some herbaceous. It is all these chemicals together, a precise amount of each, that gives each lavender variety its distinct aroma. And your nose knows this! One can tell the difference between a well-made, complex lavender oil with many notes within the aroma, and one that is flat or plain, which may be chemically imbalanced or missing some trace constituents. One can easily tell the difference, for example, between common Lavendula officinalis, and the finer Lavendula angustifolia, which contains a higher proportion of sweet-smelling linalyl acetate and less sharp-smelling camphor. Further, lower quality lavender plants may occasionally be sprayed with linalool before harvest to enhance the production of linalyl acetate by the flowers. While the end-product may smell sweeter, the process actually creates an imbalance in the overall healing synergy of the primary and trace molecules. All these oils will be labeled ‘Lavender’ on the store shelf, yet the finer, natural lavender will have a more beautiful, balanced aromatic bouquet, and is considered the most holistically healing variety by the world’s leading aromatherapy practitioners.

A balanced approach in aromatherapy, as in all of natural medicine, is best. The most effective practitioner will have a well-developed ‘internal pendulum’ combined with a solid education. Significant variations exist in the quality of essential oils; it is really cost effective to buy the higher grades of oil, as their synergy of expertly distilled chemicals will have the greater therapeutic action. Use your nose, knowledge and intuition to find a source you trust, that delivers consistently high-grade oils for a reasonable cost. Use these same faculties to skillfully select and apply the appropriate oil for each circumstance. Essential oils are complex by nature; at the same time, they have an exceptionally broad scope of therapeutic applications. Hopefully, this little bit of aromatherapy chemistry will enrich your ability to support your own health, and the health of those around you.

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