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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, why are essential oils called 'oils' anyway? They don't feel greasy, and
they tend to evaporate completely, unlike common 'fixed' oils (such as
olive, grapeseed, hazelnut and the like). Essential oils and fixed oils
share a similar chemical foundation: their structures are based on the
linking of carbon and hydrogen atoms in various configurations. But this is
really where the similarity ends. Fixed oils are made up of molecules
comprised of three long chains of carbon atoms bound together at one end,
called a triglyceride. Every fixed oil is made up of just a few different
triglyceride arrangements - olive oil, for example, is primarily made up of
oleic, linoleic and linolenic acids (the names of particular carbon-hydrogen
chains forming the triglycerides). Their long-chain shape holds them in a
liquid state which does not easily evaporate.
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.
The therapeutic action of an essential oil is primarily determined by the
functional groups found in the molecules that make up that oil (here, many
folks might be responding with "Say what?!?"). An essential oil is actually
made up of many liquid chemicals; sometimes more than one hundred distinct
chemicals are found in one pure essential oil. Each of these chemicals is
formed of a carbon-hydrogen structure with a functional group attached - it
is the combination of the base structure AND the attached functional group
that makes a single, unique molecule. And MANY of these unique molecules
combine to form ONE essential oil.
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.
The best natural, undiluted, properly distilled essential oils with all the
major and minor chemical constituents will have the finest aromas AND the
most potent 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.
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.
What does this mean to the lay-practitioner? That it's important to find a
nice smelling lavender oil! Each of the individual chemicals has a distinct
smell, talked about in terms of 'notes' within the overall lavender aroma.
Some of these are sweet, some citrusy, some are herbaceous, and some can be
camphorous. A precise amount of each will create a certain lavender aroma.
Some lavenders are more sweet (and therefore more relaxing), others are more
herbaceous (and more anti-microbial). Three important points should be noted
regarding selecting by aroma: First, there can be significantly different
aromas from the same species of plant, even when the essential oils are of
the highest quality. You can often use your intuition to select the best
variety for your needs (as between the sweeter more relaxing, or the
herbaceous more 'medicinal' lavenders). Sedond, some plants (e.g. Rosemary
and Thyme) have chemotypes - this specifies a predominant chemical in the
essential oil - ea!
ch being used for a certain therapeutic application. Know which chemotype is
best suited to your needs before making a selection. Finally, it is most
often the essential oil that smells the most 'true' to you that will be the
most beneficial. Your senses can naturally detect what is good for you and
what is not, if you're willing to listen to them impartially.
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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