An Essential Oil Chemistry Primer: Why Aroma Matters
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.
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 also 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.
This of course is not true of only lavender essential oil.
All essential oils are subject to similar variations in
production methods or the manipulation of their molecular
make-ups through the addition of synthetic chemicals. For
the most therapeutic benefit, it is always best to use
true, carefully-made essential oils. To do this, find a
source that is dedicated to supplying only the highest
grades of oils. Examine their product's aromatic quality
and business practices and so that you are comfortable with
their dedication to your health, not just their bottom
line. Listen to your intuition and your own nose; they
won't lie to you! With experience, your ability to discern
between subtly different grades of oils will become more
astute. With even more education and skill, you'll start to
recognize individual chemicals within an oils aroma, and
make the best decisions as to which oils will have the most
profound therapeutic affects for you, your family, or in
your professional practice.
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This discussion of essential oil chemistry was written by
Misty Rae Cech, a degreed naturopath, iridologist and
herbologist with a professional practice near Denver,
Colorado. She is a consultant to Ananda Aromatherapy, found
at http://www.anandaapothecary.com which offers an
extensive collection of therapeutic grade essential oils
and resources for aromatherapists and aromatherapy
enthusiasts.
