Welcome to Robert Tisserand's space. This month Robert discusses 'Does aromatherapy work?'

Does aromatherapy work?
"There are many problems with the research on aromatherapy. The biggest one is that it does not exist. There is a definite lack in the "aroma" side of aromatherapy." (Tom Hildebrandt, Psychology Department, Vanderbilt University, Nashville, Tennessee.) This comment, which I found on a website, was probably written at least 10 years ago, as the most recent article reference given on the site is for 1996, and none of the hyperlinks work.

There was in fact some pertinent research that had been published ten years ago on the "aroma" side, and much more has appeared since, much of it vindicating claims that aromatherapists have been making for years.

In an article published in the International Journal of Cardiology, the flow of blood to the heart muscle was found to significantly improve after lavender oil inhalation, and blood cortisol levels were reduced. Both of these indicate a calming effect. In a report published in Psychiatry Research, inhaling lavender oil reduced levels of salivary cortisol. Other researchers noted an average 30% reduction in adrenaline concentration after inhalation of rose oil, and patchouli oil inhalation was also notably calming. Orange or lavender oil, diffused in a dental waiting room, reduced anxiety levels and improved mood in female patients, and lavender oil reduced anxiety in patients undergoing dialysis. These are studies published in reputable journals, and often carried out at universities.

In one recent study, the researchers were not looking at stress or anxiety levels, they were looking at immune function, and the difference observed from adding essential oils was highly significant and positive.

A team at the department of psychiatry in Ohio State University found that inhaled lemon oil reliably enhanced wellbeing ("positive mood") and that this was not due to any placebo or expectation effect. A team at another department of psychiatry, in Mie, Japan, demonstrated a reduction of depressive state and an improvement in immune function after inhalation of a mixture of citrus oils.

Stimulating, anti-fatigue effects have been recorded after inhalation of pepper, peppermint or grapefruit oils. In a handful of studies, a correlation has been seen between peppermint oil or rosemary oil and increased alertness, and there are many reports of a relaxing or mild sleep-enhancing effect for lavender oil. The latter effect is quite well researched now, and we have a reasonable idea of how it operates in relation to the nervous system.

There are other effects that go beyond calming, increasing alertness, or improving mood. The aroma of peppermint oil has been found to enhance memory, and the strong associations between odour and memory, and between odour and emotion, we now know, can be used to consciously "anchor" pleasant memories and feelings (even facts) for future retrieval.

All of this research has been published in the last 10 years, in fact most of it since 2000, so this is very much an emerging field. Some reports still find no effect, and we are in the process of finding out what works and what doesn't. However, things have very much moved beyond the point of "aromatherapy is baseless", "it's all placebo", or "there's no research to back up claims" and that's without addressing issues such as medicinal effects or dermal absorption. Even for the "aroma" part of aromatherapy, the evidence for genuine effects on the human psyche is starting to accumulate.