Washington: A new study has revealed that the essential oils which form the basis of aromatherapy for stress relief also have a beneficial effect on heart rate and blood pressure following short-term exposure - and may therefore reduce the risk of cardiovascular disease.
However, those beneficial effects were reversed when exposure to essential oils lasted more than an hour, it said.
The study was performed in men and women working in various spa centres in the city of Taipei in Taiwan, where the traditions of ancient Chinese civilisations are maintained in religious ceremonies and healing therapies. Aromatherapy, as practised today, is still presented as natural healing with essential oils extracted by infusion from aromatic plants.
One hundred young, healthy non-smoking spa workers taking part in the study visited the study centre on three occasions (about once a week), when each volunteer was exposed to vapours of essential oils released from an ultrasonic ioniser for two hours.
During this time and on each visit three repeated measurements – resting heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) – were taken from each spa worker in the study room, a small space measuring 4 metres in height by 3.5 m in length and 3.2 m in width. Before each participant entered the study room, 100 percent pure bergamot essential oil was vaporised for 1 hour.
Essential oils are volatile organic compounds (VOCs) composed of hundreds of aromatic chemicals, and VOC levels in the room were also measured throughout the study period.
Results showed (after adjusting for age, sex, BMI, day of the week, and visit order) that the room`s VOC level was significantly associated with reduced blood pressure and heart rate for between 15 and 60 minutes after the start of exposure. These associations were statistically significant. For example, after 45 minutes exposure 15-minute SBP had reduced by a mean of 2.10 mmHg and heart rate by 2.21 beats per minute.
However, after exposure for more than 1 hour - from 75 to 120 minutes after the start of exposure - VOC levels became associated with an increased 15-minute mean blood pressure and heart rate. After 120 minutes, for example, mean SBP had risen from baseline by 2.19 mmHg, and heart rate by 1.70 beats per minutes.
Thus, the researchers said that, “prolonged exposure for longer than 1 hour to essential oils may be harmful to cardiovascular health in young, healthy subjects”.
“Our results suggest that exposure to essential oil for 1 hour would be effective in reducing heart rate and blood pressure. However, the most interesting finding of our study is that exposure to essential oil for over an hour was associated with elevated blood pressure and heart rate,” said investigator Dr Kai-Jen Chuang from Taipei Medical University in Taiwan.
The results were published in the European Journal of Preventive Cardiology.