Sunday, 26 February 2012

Rosemary - A Helpful Herb For Improving Cognition and Memory

Rosemary, or Rosmarinus officinalis, is an aromatic and attractive plant. It’s known as a herb but actually grows as a woody, perennial shrub with needle-like leaves and blue, purple, pink or white flowers. The fresh and dried leaves are used to flavor a wide variety of foods. Rosemary is native to the Mediterranean region and is an important part of Mediterranean cuisine, but the plant is grown in many other parts of the world as well for its culinary uses, its ornamental value and its health benefits. Rosemary doesn’t require much water and is an easy plant to grow, either in a garden or in a pot.

Rosemary: Photo by THOR at Wikimedia Commons, CC BY 2.0 License
Rosemary has long been used as a memory aid, and now modern science is providing evidence that even smelling rosemary can boost a person's cognition and memory. Recently completed research by Mark Moss and Lorraine Oliver at the University of Northumbria in the United Kingdom showed that when people were exposed to the scent of rosemary their cognitive function improved. In addition, the researchers discovered that simply smelling rosemary caused a chemical called 1,8-cineole to appear in the bloodstream of the research subjects. This chemical is present in rosemary oil and is known to be volatile - it evaporates easily and quickly at room temperature. Once the chemical was released by the rosemary it entered the noses and mouths of the research subjects and was absorbed into the blood through the linings of the nose and lungs. Individuals with high levels of 1,8-cineole in their blood had better performance in the speed and accuracy experiments that were used to test cognition. The researchers plan to investigate whether 1,8-cineole can be absorbed intact from the digestive tract when rosemary is eaten.

Interestingly, the higher the level of 1,8-cineole in the blood, the lower the "contentment level", or the worse the mood, of the subjects. The researchers suspect that the chemical affects cognition and mood by different mechanisms. In addition, the research subjects didn't seem to be more alert after inhaling rosemary vapors.

1,8-cineole belongs to a class of chemicals known as terpenes. Terpenes are fat soluble and can cross the blood-brain barrier, entering the brain. Previous research has suggested that 1,8-cineole inhibits an enzyme called acetylcholinesterase. This enzyme breaks down a neurotransmitter known as acetylcholine. Neurotransmitters are chemicals that transmit a nerve impulse from one neuron (nerve cell) to another. 1,8-cineole may affect human behavior by allowing acetylcholine to continue to function.

It's possible that other volatile chemicals from rosemary, such as rosmarinic acid, were involved in the cognition and memory boost. Rosmarinic acid is another very interesting chemical in the rosemary plant. It appears to be antimicrobial, anti-inflammatory and an antioxidant.

Herbs have had a long use in folk medicine. It's very interesting to see how today's scientists are gradually finding evidence to support some of the traditional uses of certain herbs. Many useful but as yet undiscovered medicines may be hiding in the plant kingdom, and substances in familiar plants may be shown to have medicinal benefits in the future.