Even though aromatherapy has become very popular in recent years there is little research to support many of the claims.
The small study by scientists at Ohio State University set out to examine the psychological, autonomic, endocrine, and immune effect of one ‘relaxant’ odour (lavender), one ‘stimulant’ odour (lemon), and a no-odour control (water).
During three separate visits, 56 healthy men and women were exposed to each of the odours and in order to assess the effects of expectancies the participants were given no information about the odours they would smell and what changes to expect.
Participants were monitored for blood pressure and heart rate during the experiments, and the researchers took regular blood samples from each volunteer.
The researchers taped cotton balls soaked in either lemon oil, lavender oil or distilled water below the volunteers’ noses for the duration of the tests.
The researchers tested the volunteers’ ability to heal by using a standard test where tape is applied and removed repeatedly on a specific skin site and they tested the volunteers’ reaction to pain by immersing their feet in ice cold water (32 degrees Fahrenheit/0 degrees Celsius).
The researchers found that while aromatherapy has a positive effect on mood it has no other health benefits and lemon and lavender did nothing to improve the immune status or mitigate either pain or stress.
The researchers concluded that while lemon oil reliably enhances positive mood, aromatherapy has no influence on the immune system, blood pressure, wound healing or pain control.
(Source: Psychoneuroendocrinology: the National Center for Complementary and Alternative Medicine at the National Institutes of Health: March 2008)