Henley’s Essential Oil Research Analysing The Arguments Against The Research Findings

 Connections, Autumn 2007

The Henley and Karach research that indicates that lavender and tea tree oils cause an imbalance in oestrogen and androgen pathway signalling, has certainly awoken the world of aromatherapy. A loud and
immediate ‘call to arms’ resulted in a huge number of retorts and criticisms being levelled at the study.
I decided to trawl the internet after receiving one or two emails about my article on the matter, printed in the
last Connections newsletter. Wow! I was amazed at the amount of criticism of the study that I found and
had to at once consider that I might have been hasty in my decision to take this study on face value. However, I worked my way through several of the articles and blogs that I found and soon felt assured that my decision to err on the side of caution with regard to essential oils should, and will, remain firm.

The majority of the criticism was directed at the case studies of the three boys who developed gynaecomastia. These opposing arguments I found were generally based around one of the following:The other components of these products that contained the oil/s were not considered – how do they know that it was particularly the essential oil that caused the gynaecomastia?  􀂾 How could they possibly know it was the essential oil/s – the boys could have ingested or absorbed soy or parabens, or one of the many other products that have proved to be endocrine disruptors?  How can three cases be representative of the
wider population?  As the case studies were all from the same area, shouldn’t consideration be given to
environmental factors?


Yes, soy and parabens etc are endocrine disruptors and potentially could have been ingested or absorbed by the three boys with gynaecomastia (though apparently Bloch interviewed the boys and their parents carefully
and these products were ruled out). Yes, there were only three case studies mentioned and all from the
same area in the USA. But, these arguments all miss the point; Henley and Karach’s research was not about
the three case studies per say. Bloch, the boys’ paediatric endocrinologist, passed the information on to
Henley and Karach at the National Institute of Environmental Health Sciences in Research (USA), who
both felt it worthy of investigation. The boys’ medical condition simply set off an alarm bell that acted as a
springboard activating the research itself – which ultimately took place in a laboratory.  The laboratory experiments that followed, indicated that when exposed to lavender and/or tea tree, human breast cells turned on oestrogen-regulated genes and inhibited an androgen-regulated gene. Once tested they clearly fell into the same bracket as soy, parabens, etc – i.e. they have the same potential as endocrine disruptors.

I am not an aromatherapist and would not try to dictate to someone who is that they should not be using
essential oils as a therapy. But the majority of the GICM members, in our capacity as infant massage teachers are not offering therapy. We are trying to encourage parents to massage their baby and growing child, if not daily, at least three or four times a week. The use of an essential oil as a treatment for a particular condition, such as relief for the itching that accompanies chicken pox is one thing, but for parents to regularly, over a sustained period of time, use a massage medium containing essential oils is another. Yes, it is a parent’s prerogative to use whatever massage medium they see fit to use; and I would never ‘tell’ them not to. However, where oils are concerned, we have the opportunity to advise and suggest without being dictatorial; and I will continue to let parents know what I now know, so they can at least make an informed decision about this.