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Tea tree oil
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Tea tree oil or melaleuca oil is a clear to very pale golden color essential oil with a fresh camphoraceous odor. It is taken from the leaves of the Melaleuca alternifolia which is native to the northeast coast of New South Wales, Australia. The oil has beneficial medical properties (including antiseptic and antifungal action), and is also believed to have beneficial cosmetic properties. Tea tree oil is usually used diluted, as reactions are common with pure tea tree oil.
Tea tree oil should not be confused with tea oil, the sweet seasoning and cooking oil from pressed seeds of the tea plant (drinking tea) Camellia sinensis or the tea oil plant Camellia oleifera.
indigenous Bundjalung people of eastern Australia use “tea trees” as a traditional medicine by inhaling the oils from the crushed leaves to treat coughs and colds.
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Tea tree oil or melaleuca oil is a clear to very pale golden color essential oil with a fresh camphoraceous odor. It is taken from the leaves of the Melaleuca alternifolia which is native to the northeast coast of New South Wales, Australia. The oil has beneficial medical properties (including antiseptic and antifungal action), and is also believed to have beneficial cosmetic properties. Tea tree oil is usually used diluted, as reactions are common with pure tea tree oil.
Tea tree oil should not be confused with tea oil, the sweet seasoning and cooking oil from pressed seeds of the tea plant (drinking tea) Camellia sinensis or the tea oil plant Camellia oleifera.
History and extraction
The indigenous Bundjalung people of eastern Australia use “tea trees” as a traditional medicine by inhaling the oils from the crushed leaves to treat coughs and colds. They also sprinkle leaves on wounds, after which a poultice is applied. In addition, tea tree leaves are soaked to make an infusion to treat sore throats or skin ailments.
Use of the oil itself, as opposed to the unextracted plant material, did not become common practice until researcher Arthur Penfold published the first reports of its antimicrobial activity in a series of papers in the 1920s and 1930s. In evaluating the antimicrobial activity of M. alternifolia, tea tree oil was rated as 11 times more active than phenol.
The commercial tea tree oil industry was born after the medicinal properties of the oil were first reported by Penfold in the 1920s. It was produced from natural bush stands of M. alternifolia that produced oil with the appropriate chemotype. The plant material was hand cut and often distilled on the spot in makeshift, mobile, wood-fired bush stills.
Production ebbed after World War II as demand for the oil declined, presumably due to the development of effective antibiotics and the waning image of natural products. Interest in the oil was rekindled in the 1970s as part of the general renaissance of interest in natural products. Commercial plantations were established in the 1970s and 1980s, which lead to mechanization and large-scale production of a consistent essential oil product.
Among over 98 compounds contained in the oil, terpinen-4-ol is responsible for most of the antimicrobial actions.citation needed
Although tea tree oil is normally extracted from Melaleuca alternifolia commercially, it can also be extracted from Melaleuca dissitiflora and Melaleuca linariifolia. Tea tree oil is defined by international standard ISO 4730 (2004) ("Oil of Melaleuca, Terpinen-4-ol type"), which specifies levels of 15 components which are needed to define the oil as "tea tree oil."
Composition
| Compound
| Tea tree oil ISO 4730 (2004) Concentration [%] |
|---|
| terpinen-4-ol | 30-48 | | ?-terpinene | 10–28 | | a-terpinene | 5–13 | | 1,8-Cineole | 0–15 | | a-terpinolene | 1.5–5 | | a-terpineol | 1.5–8 | | a-pinene | 1–6 | | p-cymene | 0.5–8 |
Medicinal use
Tea tree oil has been recognized as a potent antiseptic in Australia anecdotally for much longer than there has been scientific evidence. However, recent studies support a role for tea tree oil in skin care and treatment of various ailments.
Tea tree oil is a known antifungal agent, effective in vitro against multiple dermatophytes found on the skin. In vivo, shampoo with 5% tea tree oil has been shown to be an effective treatment for dandruff due to its ability to treat Malassezia furfur, the most common cause of the condition.
Effectiveness of topical tea tree oil preparations for Candidiasis is supported by their ability to kill Candida in vitro.
In the treatment of moderate acne, topical application of 5% tea tree oil has shown an effect comparable to 5% benzoyl peroxide, albeit with slower onset of action. In another study in 2007 5% strength gel was compared against a placebo, with statistically significant results.
There is some limited research that has shown that tea tree oil may have topical anti-viral activity, especially with the Herpes virus (cold sores, chicken pox and shingles blisters, etc.)
One study has shown a 5% tea tree oil solution to be more effective than commercial medications against the scabies mite in an in vitro situation.
Flea control
Tea tree oil has long been used as a method of all natural effective flea control by adding the oil directly to dogs, horses and sheep fur or their bathing water. Use on cats has been known to make them sick and in some cases kill them, this is due to cats licking their fur and consuming the oil.
According to National Animal Poison Control Center, the use of tea tree oil in dogs has been associated with hypothermia, muscle weakness, ataxia, tremors, altered behavior, paralysis. A case report has been published in which three cats had clinical signs and one cat died after being treated with the oil.
Safety
According to the American Cancer Society: "Tea tree oil is toxic when swallowed. It has been reported to cause drowsiness, confusion, hallucinations, coma, unsteadiness, weakness, vomiting, diarrhea, stomach upset, blood cell abnormalities, and severe rashes. It should be kept away from pets and children."
A small number of people experience allergic contact dermatitis as a reaction to dermal contact with tea tree oil. In an Italian study of 725 consecutive patients, patients were patch tested with undiluted, 1% and 0.1% Tea Tree Oil. For undiluted tea tree oil, nearly 6% of the patients observed positive reactions of skin irritation. Only 1 of 725 patients observed a positive reaction of skin irritation with the 1% dilution. None of the 725 patients observed adverse reactions with the 0.1% dilution. Allergic reactions may be due to the various oxidation products that are formed by exposure of the oil to light and/or air.
External application of undiluted tea tree oil and/or at inappropriate high doses has been associated with toxicity, including death, in cats and other animals.
A disputed case study reported in The New England Journal of Medicine concluded that "repeated topical exposure to lavender and tea tree oils probably caused prepubertal gynecomastia" (abnormal breast development) in three young boys. The study involved just three individuals and found lavender to be the only common ingredient used by the boys in the study. While all three cases involved the use of products containing lavender oil as an ingredient, only one boy also used products containing tea tree oil. In all cases, the prepubertal gynecomastia reversed after several months.
Use of the products containing lavender and tea tree oils were also discontinued during this time. In the same paper, results from cell culture assays indicated that both essential oils exhibit weak estrogenic and antiandrogenic properties in vitro, but no tests were conducted in vivo. Researchers also indicated that other components in these products may also have contributed to the gynecomastia, or that genetics might play a role. Researchers also noted that estrogenic or antiandrogenic activities have also been reported for some other commonly used essential oils as well as some foods such as almonds and peanuts, but cited no associated cases of prepubertal gynecomastia.
If used in concentrations below 4% or particularly below 1%, tea tree oil may fail to kill bacteria and create an evolutionary pressure which may result in them becoming less sensitive to tea tree oil and even some antibiotics in vitro.
Tea tree oil may cause hearing loss when used in the ears.
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