A diffuser and a bottle of essential oil
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Aromatherapy uses plant materials and aromatic plant oils, including essential oils, and other aroma compounds, with claims for improving psychological or physical well-being. It is offered as a complementary therapy or as a form of alternative medicine, the first meaning alongside standard treatments, the second instead of conventional, evidence-based treatments.
Aromatherapists, people who specialize in the practice of aromatherapy, utilize blends of therapeutic essential oils that can be used as topical application, massage, inhalation or water immersion. There is no good medical evidence that aromatherapy can either prevent or cure any disease. Placebo-controlled trials are difficult to design, as the point of aromatherapy is the smell of the products. There is some evidence that it is effective in combating postoperative nausea and vomiting.
The use of essential oils for therapeutic, spiritual, hygienic and ritualistic purposes goes back to a number of ancient civilizations including the Chinese, Indians, Egyptians, Greeks, and Romans who used them in cosmetics, perfumes and drugs. Oils were used for aesthetic pleasure and in the beauty industry. It was a luxury item and a means of payment. It was believed the essential oils increased the shelf life of wine and improved the taste of food.
Oils are described by Dioscorides, along with beliefs of the time regarding their healing properties, in his De Materia Medica, written in the first century. Distilled essential oils have been employed as medicines since the eleventh century, when Avicenna isolated essential oils using steam distillation.
In the era of modern medicine, the naming of this treatment first appeared in print in 1937 in a French book on the subject: Aromathérapie: Les Huiles Essentielles, Hormones Végétales by René-Maurice Gattefossé, a chemist. An English version was published in 1993. In 1910, Gattefossé burned a hand very badly and later claimed he treated it effectively with lavender oil.
Modes of application
The modes of application of aromatherapy include:
- Aerial diffusion: for environmental fragrancing or aerial disinfection
- Direct inhalation: for respiratory disinfection, decongestant, expectoration as well as psychological effects
- Topical applications: for general massage, baths, compresses, therapeutic skin care
Some of the materials employed include:
- Absolutes: fragrant oils extracted primarily from flowers or delicate plant tissues through solvent or supercritical fluid extraction (e.g., rose absolute). The term is also used to describe oils extracted from fragrant butters, concretes, and enfleurage pommades using ethanol.
- Aroma lamps or diffusers: an electric or candle-fueled device which volatilizes essential oils, usually mixed with water.
- Carrier oils: typically oily plant base triacylglycerides that dilute essential oils for use on the skin (e.g., sweet almond oil).
- Essential oils: fragrant oils extracted from plants chiefly through steam distillation (e.g., eucalyptus oil) or expression (grapefruit oil). However, the term is also occasionally used to describe fragrant oils extracted from plant material by any solvent extraction. This material includes incense reed diffusers.
- Herbal distillates or hydrosols: the aqueous by-products of the distillation process (e.g., rosewater). Common herbal distillates are chamomile, rose, and lemon balm.
- Infusions: aqueous extracts of various plant material (e.g., infusion of chamomile).
- Phytoncides: various volatile organic compounds from plants that kill microbes. Many terpene-based fragrant oils and sulfuric compounds from plants in the genus "Allium" are phytoncides, though the latter are likely less commonly used in aromatherapy due to their disagreeable odors.
- Vaporizers: typically higher oil content plant based materials dried, crushed, and heated to extract and inhale the aromatic oil vapors in a direct inhalation modality.
Aromatherapy is the treatment or prevention of disease by use of essential oils. Other stated uses include pain and anxiety reduction, enhancement of energy and short-term memory, relaxation, hair loss prevention, and reduction of eczema-induced itching. Two basic mechanisms are offered to explain the purported effects. One is the influence of aroma on the brain, especially the limbic system through the olfactory system. The other is the direct pharmacological effects of the essential oils. Aromatherapy has been criticized as pseudoscientific fraud.
Choice and purchase
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Oils with standardized content of components (marked FCC, for Food Chemicals Codex) are required[by whom?] to contain a specified amount of certain aroma chemicals that normally occur in the oil. There is no law that the chemicals cannot be added in synthetic form to meet the criteria established by the FCC for that oil. For instance, lemongrass essential oil must contain 75% aldehyde to meet the FCC profile for that oil, but that aldehyde can come from a chemical refinery instead of from lemongrass. To say that FCC oils are "food grade" makes them seem natural when they are not necessarily so.
Undiluted essential oils suitable for aromatherapy are termed 'therapeutic grade', but there are no established and agreed standards for this category.
Analysis using gas liquid chromatography (GLC) and mass spectrometry (MS) establishes the quality of essential oils. These techniques are able to measure the levels of components to a few parts per billion. This does not make it possible to determine whether each component is natural or whether a poor oil has been 'improved' by the addition of synthetic aromachemicals, but the latter is often signaled by the minor impurities present. For example, linalool made in plants will be accompanied by a small amount of hydro-linalool, whilst synthetic linalool has traces of dihydro-linalool.
There is no good medical evidence that aromatherapy can prevent or cure any disease. In 2015, the Australian Government's Department of Health published the results of a review of alternative therapies that sought to determine if any were suitable for being covered by health insurance; aromatherapy was one of 17 therapies evaluated for which no clear evidence of effectiveness was found. Evidence for the efficacy of aromatherapy in treating medical conditions is poor, with a particular lack of studies employing rigorous methodology. A number of systematic reviews have studied the clinical effectiveness of aromatherapy in respect to pain management in labor, the treatment of post-operative nausea and vomiting, managing behaviors that challenge in dementia, and symptom relief in cancer. All of these reviews report a lack of evidence on the effectiveness of aromatherapy. Studies were found to be of low quality, meaning more well-designed, large scale randomized controlled trials are needed before clear conclusions can be drawn as to the effectiveness of aromatherapy.
Because essential oils are highly concentrated they can irritate the skin when used in undiluted form. Therefore, they are normally diluted with a carrier oil for topical application, such as jojoba oil, olive oil, or coconut oil. Phototoxic reactions may occur with citrus peel oils such as lemon or lime. Also, many essential oils have chemical components that are sensitisers (meaning that they will, after a number of uses, cause reactions on the skin, and more so in the rest of the body). Chemical composition of essential oils could be affected herbicides if the original plants are cultivated versus wild-harvested. Some oils can be toxic to some domestic animals, with cats being particularly prone.
A report of three cases documented gynecomastia in prepubertal boys who were exposed to topical lavender and tea tree oils. The Aromatherapy Trade Council of the UK issued a rebuttal. The Australian Tea Tree Association, a group that promotes the interests of Australian tea tree oil producers, exporters and manufacturers issued a letter that questioned the study and called on the New England Journal of Medicine for a retraction. Another article published by a different research group also documented three cases of gynecomastia in prepubertal boys who were exposed to topical lavender oil.
While some advocate the ingestion of essential oils for therapeutic purposes, licensed aromatherapy professionals do not recommend self-prescription due to the highly toxic nature of some essential oils. Some very common oils like eucalyptus are extremely toxic when taken internally. Doses as low as 2 mL have been reported to cause clinically significant symptoms and severe poisoning can occur after ingestion of as little as 4 mL. A few reported cases of toxic reactions like liver damage and seizures have occurred after ingestion of sage, hyssop, thuja and cedar oils. Accidental ingestion may happen when oils are not kept out of reach of children. As with any bioactive substance, an essential oil that may be safe for the general public could still pose hazards for pregnant and lactating women.
Oils both ingested and applied to the skin can potentially have negative interactions with conventional medicine. For example, the topical use of methyl salicylate-heavy oils like sweet birch and wintergreen may cause bleeding in users taking the anticoagulant warfarin.
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