Oils ain’t oils: the essentials

2 06 2009

ResearchBlogging.orgYou may have noticed my general feeling about so-called “alternative medicine” is that there is no “alternative” to medicine. One of my friends puts it another way:

Q. What do you call an alternative medicine that works?

A. Medicine.

There is no grand pharmaceutical conspiracy against natural remedies. Once a treatment demonstrates value to medical science, it will become accepted as medicine. That’s why, while you last month science bloggers descended upon a laughably flawed acupuncture study flouted as proof of effect and tore it to pieces, I doubt there’ll be a similar response at this a new international study currently in print that shows essential oils may have a role to play in combating infections caused by multi-resistant microbes.

It’s actually quite a well done study, with interesting results that provide an opportunity for the complementary medicine industry to clean up it’s act and get on board with whole evidence-based medicine paradigm, rather than remaining in the realm of snake oil and shamanism.

Because I want to conserve space I’ll let you do your own googling to find out what exactly “essential oils” are – in a nutshell they are generally oily, smelly plant extracts and have been used internationally as traditional medicines for what is known as “donkey’s ages”. The antimicrobial nature of several oils, such as tea tree and eucalyptus oils is well known.

The researchers measured the the inhibitory effect of 13 different individual oils had on plated microbial cultures. Quite a similar test to how antibiotic susceptibility or resistance. The researchers also used very effective controls. Not only did they use similar substances with no suspected antimicrobial activity – olive oil and industrial paraffin – they also used known antiseptic substances to compare the expected effect of the oils – ethanol, iodine, hydrogen peroxide, and chlorohexidine. The results are in the below figure.

Figure 1 - Warnke et al - inhibition zones of essential oils and controls

They also tested the oils against against four different microbes, all known to be risky infections in hospitals – Staphylococcus aureus (A), Staphylococcus epidermis (B), Streptococcus sp. (C) and Candida sp. (D). Candida is a fungus, while the other three are bacteria. The different colour bars represent different samples of microbes. The higher the bar the more microbe was inhibited by the substance. For those of you not keen on squinting the thirteen oils are on the left, followed by the two non-essential oils, and then ethanol and the other antispetics.

From this chart we can see all the oils exhibited some antimicrobial activity against all four microbes (okay, lie, Sandalwood was ineffective against Candida^). Not only that, but in most cases the inhibitory was quite similar to currently used antiseptics. What is impressive is the far superior antimicrobial power exhibited by the oils on the far left. Some of these oils had almost triple the potency of ethanol or hydrogen peroxide. Impressive.

One thing to note is that these super-oils are not those oils you hear about. Tea tree, eucalyptus and grapefruit oils are the weedly little bars just after the four massive towers of potency. The four most successful oils were Thyme white (Australia), Lemon (Nepal), Lemongrass (Australia) and Cinammon (India).

Unfortunately the vast amount of existing literature on essential oils has focused on popular treatments, particularly tea tree oil. I can’t help consider that it appears unfortunate that so much energy has been directed towards an oil that may only have activity similar to that of standard antiseptics, when a simple comparative study like this reveals there are much much much more potent targets to examine out there. Perhaps there are other factors at play, but my thoughts wonder if it is because tea tree and eucalyptus have such a tie to traditional Australian medicines?

Relying on anectdotes or tradition for guidance may well serve a good starting point, but without research it’s almost meaningless. Research in genuine controlled studies is the only way that mode of action can be verified. Not only that, research is the only way of identifying more successful treatments, whether by looking at natural cousins or synthetic derivatives. By not engaging in research we run the risk of stagnating, and using sub-optimal treatments.

Well designed and executed clinical research like this into complementary and traditional medicines should be encouraged. This is what an organisation like NCCAM should be supporting if it wishes to be taken seriously by the evidence-based medicine community. The complementary medicines industry needs utilise publications like this to distance itself from the Grand CAM Sham. While alternative medicines are based on a clear ignorance of basic physiology and science* – many complementary supplements have a clear physiological basis that can be defined and measured if they so chose to do so.

^1 out of 52 tests ain’t bad

*They damn well know this too, or they would not embrace the false dichotomy of alternatives to medicine.


Warnke PH, et al (2009). The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections Journal of Cranio-Maxillofacial Surgery DOI: 10.1016/j.jcms.2009.03.017
(Access to the pre-print in pdf available at 6minutes.com)

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One response

9 06 2009
fx15 lida yılan yağı karınca yumurtası xacc

Thank you very much for this information.
Good post thanks for sharing.
I like this site ;)

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