Prolonged aromatherapy may be harmful to your heart: study

In the study, 100 spa workers in Taipei sat in a room and breathed in the vapours of bergamot oil - a concentrated, citrusy extract - for two hours, while researchers measured their blood pressure and heart rate, as well as the level of volatile organic compounds (VOCs) in the air, website MyHealthNewsDaily reported.

VOCs are substances, including essential oils, which easily evaporate at room temperature.

During the first hour, the workers' blood pressure and heart rates went down. After 45 minutes, the average systolic blood pressure measurement had dropped by 2.10 mmHg, and the heart rate by 2.21 beats per minute.

This finding agrees with some previous research showing essential oils relieve stress.

However, after 120 minutes, researchers saw the opposite effect. Systolic blood pressure not only returned to the baseline level, it had risen by about 2.19 mmHg, and the heart rate was 1.70 beats per minute higher than at baseline.

"These findings suggest that overexposure to essential oil might be harmful to cardiovascular health," the researchers wrote in the European Journal of Preventive Cardiology.

Previous studies have linked VOCs with an increased risk of asthma, as well as death from cardiovascular disease.

Breathing these compounds may increase inflammation in the body, and alter nervous system functioning, which could then affect heart health, the researchers said.

However, further studies are needed to confirm the new results. While elevated blood pressure and heart rate are markers for cardiovascular disease, it's not clear whether small, short-term fluctuations in these measures could lead to heart problems, the researchers were quoted as saying by the website.

In addition, because the researchers measured total VOC levels, other compounds in the air besides those from the oil vapour itself could have influenced the results.

"The finding brings to light that more isn't better all the time," said Dr Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City, who was not involved in the study.

While the findings are preliminary, it would be concerning if the elevated heart rate and blood pressure seen in the study were chronic, Steinbaum said.