Report by National Chung Hsing University Reveals the Secrets of Phytoncides

March 12, 2009

Many people know that it is good for your health to walk in a forest and be exposed to the phytoncides they give off. However, most people have no knowledge of the constituents of these phytoncides. Associate Professor David Wang of the Department of Forestry and Associate Professor Jiunn-wang Liao of the Graduate Institute of Veterinary Pathology, National Chung Hsing University, have published Taiwan's first report on the constituents of phytoncides. The research confirms that the limonene phytoncide promotes sleep, and helps fight anxiety and ease pain.

Due to the absence of an adequate collection technique, there has been no academic report on phytoncides in Taiwan and few research projects have been conducted overseas. Under the auspices of the Forestry Bureau, Prof. Wang spent four years shuttling between the university's Black Forest and the Hui-Sun Forest Station, Aowanda's Sweet Gum Forest, and Hsitou's Cryptomeria japonica Forest, collecting air samples using solid-phase microextraction, synthetic resin and portable pumps. After phytoncides are extracted from the air samples, they are isolated and analyzed using a gas chromatography-mass spectrophotometer (GC-MS). The researchers found that the constituents of phytoncides are similar to those of distilled Cryptomeria japonica essential oil.

"Phyton" means "plant" in Latin, and "cide" is the natural substance (collectively referred to as a compound) that a plant gives off to kill microorganisms. In fact, phytoncides do not only exist in forests. They can be found in vegetables and fruit as well. After the constituents of phytoncides were identified, experiments were conducted on animals using Cryptomeria japonica essential oil.

After being given Cryptomeria japonica essential oil, the rats were put to sleep through pharmaceutical means and it was found that Cryptomeria japonica essential oil improved their sleep quality. In addition, the researchers used an elevated plus maze to measure the impact phytoncide had on the rats. They discovered that a higher percentage of rats entered the open area and those that did stayed there for longer periods of time. Moreover, phytoncide was found to have a pain amelioration effect. Scientific data were utilized to prove that the Cryptomeria japonica essential oil in the phytoncides contains limonene, a key terpene constituent, that influences the central nervous system to a large extent, improves sleep quality, and helps fight anxiety and ease pain. The experiments also reveal that even given extremely high doses of Cryptomeria japonica essential oil, the rats demonstrated no toxic reaction, indicating that Cryptomeria japonica essential oil is safe to use.

Prof. Wang notes that the phytoncide concentration in a Cryptomeria japonica forest varies as the temperature changes. The concentration peaks at a temperature of around 30 degrees Celsius, and it is higher in the summer than in the winter. Since Cryptomeria japonica essential oil and phytoncides share similar constituents, people who rarely visit Cryptomeria japonica forests may use Cryptomeria japonica essential oil in their bathrooms in place of phytoncides.