What is Tea Tree Oil?
Tea tree oil is an essential oil that is distilled from the bark of the tea tree. There are several species of tea tree, but most essential oil is made from the bark of the Narrow-Leaved Paperbark Tree (Melaleuca alternifolia), a plant that is native to Australia. Preparations of the bark of this tree have been an important part of Aboriginal medicine for thousands of years. The bark of the tree peels away in paper like sheets that can be used for bandages and sleeping mats. In addition, the bark contains is rich in volatile molcules, which are both pungent and antimicrobial. Numerous studies have shown that these compounds, which are also present in the essential oil, are toxic to a wide range of bacteria and fungi. These antibacterial and antifungal compounds originally evolved to protect the Tea Tree from infection and disease, which they do quite effectively. Narrow Leaved Paperbark Trees grow in moist and swampy regions in the northern part of Australia, an area where there are a lot of bacterial and fungal plant pathogens. To succeed in a hostile environment like this, the Narrow Leaved Paperbark Tree has developed the arsenal of natural compounds that we now harvest and use in the form of tea tree essential oil.
The Composition of Tea Tree Essential Oil
Standard tea tree oil is a blend of almost 100 different molecules, although most of these are only present in very small quantities. Most of the compounds in tea tree oil are derivatives of terpene, a molecule that is produced by many plants. The major components of tea tree oil are terpinen-4-ol, gamma-terpinene and alpha-terpinene. Terpinen-4-ol is the most well studied of these molecules, and research has shown that it has potent antibacterial properties. Other secondary compounds in tea tree oil are suspected to act synergistically with terpinen-4-0l, to kill bacteria. Interestingly, some research has shown that some of the components in tea tree oil may interfere with the antibacterial activity of terpinen-4-0l. The researchers hypothesized that the presence of certain components made the terpinen-4-0l less soluble, causing less of it to reach the bacteria. Not all tea tree oil is the same because of differences in the source and how it is processed. However, tea tree oil is one of the most popular essential and there are international standards for the types of mixtures that can be marketed and sold as tea tree oil. The table at right indicates the range of differences that are generally required for a product to be called tea tree oil.
Medicinal Properties of Tea Tree Oil
The succesful use of tea tree extracts in indigenous medicine has inspired chemists, biologists and doctors to investigate the efficacy of this compound in the treatment of a wide range of diseases. Several studies have shown that tea tree oil is toxic to many types of bacteria, including Propionibacterium acnes. The same is true for several types of fungal pathogens. Tea tree oil is commonly used in soaps, lotions and wound dressings in both naturopathic and modern medical settings. Of particular interest has been the antibacterial activity of tea tree oil against Methicillin Resistant Staphyloccocus Aureus (MRSA). Because MRSA is very resistant to many commonly used antibiotics, researchers and doctors are interested in identifying new compounds to treat MRSA infections. Research into the use of MRSA and other diseases has been promising, but not necessarily conclusive. Most of the testing (which is similar to antibiotic susceptibility testing) is done in the lab, and the results do not necessarily translate to human use. Additionally, there is some danger that tea tree oil may be irritating to the skin. Several people have reported allergic reactions to tea tree oil (which is true for most other topicals too). However, a study of over 700 people showed that less than 1% of people had irritation from use of a 5% tea tree oil solution. Higher concentrations of tea tree oil are known to cause more frequent side effects. Most naturopathic practitioners recommend diluting tea tree oil to 25% or less, before use.
Tea Tree Oil and Acne
There are only a few real studies into the efficacy of tea tree oil in improving acne symptoms. One study found that a topical 5% tea tree oil aolution was approximately as effective as benzoyl peroxide. Basically, the tea tree oil was mildly helpful but did not significantly improve acne symptoms for most patients. On the plus side, tea tree oil had fewer side effects (dry skin, itching, redness, etc) than benzoyl peroxide. The major limitation of topical tea tree oil is the same as for most other topical antibiotic treatments; the antibacterial compounds do not effectively penetrate to the site of infection. In many cases of moderate to severe acne, an overgrowth of P. acnes bacteria occurs deep within the follicle and sebaceous gland. This location is not accessible to many of the antibacterial molecules found in topical acne treatments. This limitation means that tea tree oil, and most other topical treatments, are largely innefective against moderate and severe forms of acne.
Related Pages at The Science of Acne
Additional Online Resources
Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes.
Raman, et al. 2008. For article abstract, click here.
The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: A randomized, double-blind placebo-controlled study.
Enshaieh, et al. 2007. For article abstract, click here.
A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne.
Bassett, et al. 1990. For article abstract, click here.
Therapeutic agents and herbs in topical application for acne treatment.
Kanlayavattanakul, et al. 2010. For article abstract, click here.
The mode of antimicrobial action of the essential oil of Melaleuca alternifolia (tea tree oil).
Cox, et al. 2000. For article abstract, click here.
Safety, efficacy and provenance of tea tree (Melaleuca alternifolia) oil.
Carson, et al. 2001. For article abstract, click here.
Melaleuca alternifolia (Tea Tree) Oil: a Review of Antimicrobial and Other Medicinal Properties.
Carson, et al. 2006. For article abstract, click here.
Is tea tree oil an important contact allergen?
Veien, et al. 2004. For article abstract, click here.
Composition of Australian Tea Tree Oil (Melaleuca alternifolia).
Swords, et al. 1978. For article abstract, click here.
Antibacterial Activity of Essential Oils from Australian Native Plants.
Wilkinson, et al. 2005. For article abstract, click here.
A review of the toxicity of Melaleuca alternifolia (tea tree) oil.
Hammer, et al. 2006. For article abstract, click here.