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A whiff of rosemary gives your brain a boost

By Andrew Winner

Could the smell of rosemary enhance your time on a crossword puzzle? It's possible, according to a new study.

Researchers noted the surprising appearance of a component of rosemary oil in the bloodstream, leading to new ideas about how rosemary aroma can be used therapeutically. The results will be published in Therapeutic Advances in Psychopharmacology, a journal published by SAGE Publications.

Rosemary has a long history as a traditional remedy with such widespread uses as a hair rinse and a cat repellent. When steamed, some say it can treat bronchitis and other forms of congestion, while the link between rosemary and improved cognitive function has long been established.

Dr. Mark Moss, who devised and wrote the study, was interested in rosemary’s fragrant aroma, which has long been cherished by chefs and bakers. Could the 1,8-cineole, a constituent part of rosemary oil, be detected in the bloodstream after exposure to just the aroma?

“We were not surprised by the improvement in cognitive performance following exposure to rosemary aroma as this has been demonstrated previously,” Moss wrote in an e-mail. “What excited us was the demonstration that performance was linked to plasma levels of 1,8-cineole following exposure.” 

In the study, a cohort of 20 subjects were exposed to varying levels of the aroma, then given a battery of cognitive tests and mood assessments. Not surprisingly, the cognitive performance of the subjects increased, with a corresponding mood increase of lesser magnitude. However, the real surprise came when the blood tests were processed.

The results showed absorption of 1,8-coneole into the bloodstream, meaning the natural compound was absorbed through the nose and into the blood plasma. For Moss, this means there is a more traditional biochemical explanation for the increased cognitive performances previously demonstrated.

“This compound is present in rosemary but has not previously been demonstrated to be absorbed into blood plasma in humans,” Moss added. “It is our view that the aroma therefore acts like a therapeutic drug, rather than any effects being a result of the more sensory properties of the aroma.”

Moss reminds that it’s easy to forget how many of our therapeutic drugs are the result of plant science. His team will continue to investigate the therapeutic benefits of several common plants, including peppermint and lavender. An upcoming study with rosemary will aim to determine whether 1,8-cineole, when ingested orally, can survive the rigors of the gastrointestinal system to be similarly absorbed into the bloodstream. 

The potential benefits of the research are extremely wide-ranging.

“Plants are very complex organisms and contain many different active compounds and these vary in concentration from plant to plant and even within the same plant over the course of a day,” Moss notes.  “The accumulation of knowledge regarding possible impacts of plant aromas and extracts could potentially lead to an identification of the best combination to promote specific effects.” 

“At its grandest conclusion might be the development of plant-based drugs that might extend mental capacity into old age through pharmacological challenge to decline,” Moss concludes.