Introduction to aromatherapy

CHAPTER 4 INTRODUCTION TO AROMATHERAPY


The term ‘aromatherapy’ refers to the use of essential oils and is an aspect of phytotherapy (botanical medicine). Essential oils are volatile liquid substances extracted from plant material by a variety of methods. However, ‘aromatherapy’ is frequently associated with cosmetic products that often do not contain any essential oils, even though the term ‘aromatherapy’ is included on the labels and advertising material of such products. There are several definitions of aromatherapy. Hirsch, for example, defines it as ‘the use of odorants as inhalants to treat underlying medical or psychiatric symptoms’ (Hirsch 2001), but this definition does not mention essential oils or differentiate between essential and fragrant (synthetic) oils, which are not usually recommended for use in healthcare. In addition, for the administration method Hirsch refers only to inhalation. Thus, Hirsch’s definition does not accurately define aromatherapy or describe the way it is practised. For the purposes of this chapter, aromatherapy is defined as follows:



In this context ‘controlled’ encompasses:


quality use of essential oils (QUEO) (Dunning 2005), which is based on the principles of the Quality Use of Medicines (Department of Health and Aged Care 1999)








HISTORICAL OVERVIEW


Use of essential oils is recorded in most ancient civilisations in healthcare, religion and cosmetics, and to enhance the environment. For example, the ancient Egyptians used them to embalm the dead as well as in healthcare. Almost all cultures used odorants, including plant oils, as preventative measures and to fumigate people and environments during illnesses, such as the plague. In the Middle East, Avicenna (AD 980–1037) is credited with developing the original steam distillation process for extracting essential oils. In the late 1800s, Chamerland undertook research into the antiseptic properties of essential oils and in the 20th century Cavel, who studied the antiseptic properties of 35 essential oils in sewerage cultures, extended Chamerland’s work.


A great deal of modern research concerns the relationship between odours and emotional states, cognitive performance (Jellinek 1998/99, Svoboda 2002, Van Toller & Dodd 1988) and stress management. It also focuses on the management of common health problems, such as upper respiratory tract infection (URTI) and acute and chronic pain, in a range of healthcare settings that include aged care, midwifery and acute care such as coronary care units. Often the research is conducted on isolated chemical components of the essential oil, which does not reflect usual aromatherapy practice.


René Gattéfosse is credited with coining the term ‘aromatherapy’. After burning his hand in a laboratory fire, he immersed it in a vat of lavender essential oil, which reduced the pain, and his hand subsequently healed without scarring or infection. Gattéfosse went on to use essential oils in military hospitals in World War I. Essential oils also played a major role in wound care during World War II, where Dr Jean Valnet used them in military hospitals in Europe and IndoChina. Marguerite Maury is largely responsible for the popularity of essential oils in modern beauty care. She introduced aromatherapy into the UK in the 1960s, and her technique of using low doses of essential oils dispersed in a carrier oil and applied in a massage strongly influenced aromatherapy practice in the UK and Australia (Price & Price 1995). Research into the therapeutic application of essential oils is continuing in many countries in animal and human subjects.



AROMATHERAPY PRACTICE MODELS


There are three main aromatherapy practice models, which have implications for the administration/application method, dose, dose intervals and safety. Essential oils are often combined with other conventional and complementary therapies such as massage and acupressure.






ESSENTIAL OILS



CHEMISTRY


Essential oils are secondary plant metabolites and are complex chemical compounds that have a different composition from the herb extract of the same plant. Essential oils are stored in specific secretory structures in leaves, twigs, seeds, petals, bark and roots, often with resins and gums in oil cells, sacs, resin canals, ducts and hairs, and are extracted from these structures by steam distillation, expression, enfleurage, solvent extraction, maceration and more recently supercritical carbon dioxide extraction, depending on the plant source (Guba 2002, Price & Price 1995). More than 3000 odour molecules have been identified.


Chemical variations are common in plants of the same genus and these are known as chemotypes. The best known chemotypes occur in the essential oils of Thymus vulgaris (thyme), Rosmarinus officinalis (rosemary), Ocimum basilicum (basil), and Melaleuca alternifolia (tea tree). Growing conditions, harvesting, storage and handling are known to affect the chemical composition of essential oils (Guba 2004, Price & Price 1995). Common phytochemicals in essential oils are terpenes, sesquiterpenes, alcohols, phenols, aldehydes, ketones, esters, acids, phenolic ethers, oxides, lactones and coumarins (Bowles 2003, Clarke 2002). It is necessary to understand the chemical composition of essential oils in order to understand their application in healthcare and the safety aspects associated with their use.


Of the many chemicals present, the alcohols, lactones, phenols and sesquiterpenes are considered to have a major impact on the odour of the oil and are of particular significance in the cosmetic and perfumery applications of aromatherapy. Of these chemicals, alcohols are considered to be among the most important for therapeutic effect and pleasant fragrance. They often have antimicrobial properties and low toxicity, and are described as warming, uplifting and good general tonics. Two examples of alcohols found in essential oils are:




The sesquiterpenes consist of three isoprene units and make up the largest group of terpenes found in the plant world. They tend to have strong odours and a variety of pharmacological effects. Two examples of sesquiterpenes found in essential oils are:




Optical isomerism also influences the odour of a substance, so two different oils containing the same specific chemical may have different odours because the chemicals are stereoisomers. For example, d-limonene found in citrus oils, pine leaves and peppermint has a citrus odour, whereas its stereoisomer l-limonene has a turpentine-like odour and is found in citronella and lemon verbena.


Although the pharmacological effects of many of the constituents found in essential oils have not yet been fully investigated, a few that have been investigated are notable for their significant activity. For example, eugenol is a phenol found in cinnamon, oil of cloves and ylang ylang, giving the oils a spicy, pungent odour and significant antimicrobial activity. Cinnamaldehyde, chiefly found in cinnamon oil, has also been well investigated. It has antispasmodic, antimicrobial and fungicidal activities and is described as having a warm, spicy and balsamic odour.


Most of the essential oils produced are used in the food, cosmetic and, to a lesser extent, medicine industries, where strict composition standards are needed to ensure products meet relevant standards. Organisations such as the International Organisation for Standardisation (ISO), Research Institute for Fragrance Materials (RIFM), International Fragrance Association (IFRA) and Association Française de Normalisation (AFNOR) have developed composition standards for many essential oil products used in the food and perfume industries, and this is an important aspect of quality control. The ISO and AFNOR standards are often accepted as the most reliable indicators of quality.


The need to achieve compositional consistency has led some manufacturers to artificially manipulate chemical composition, using adulteration, substitution and rectification, to ensure essential oils meet the standard and to reduce the cost of expensive oils such as rose and jasmine. Plant conservation issues have also affected aromatherapy practice: for example, the sale of essential oils from some endangered species is banned in Europe. In some cases synthetic products have been developed, which may increase the potential to cause adverse events and bring aromatherapy into disrepute. The European Federation of Essential Oils was formed in 2002 to increase awareness of the need for sustainable harvesting to benefit both local communities and aromatherapy, as well as to conserve endangered plants.


Analytical techniques such as gas chromatography, mass spectrometry, infrared spectroscopy, optical rotation and refractive index are used to assess the composition and purity of essential oils. Frequently mass spectrometry and infrared spectroscopy are considered together. The analytical information, together with other safety information, is detailed in material safety data sheets, which are available from essential oil suppliers and manufacturers. More recently, the cosmetic industry has begun to examine the peroxide value (POV) of both essential and fixed vegetable oil carrier oils. POV is an indicator of the potential of an essential oil to cause skin irritation and sensitivity (Wabner 2002). In addition, the physical appearance (colour and consistency) and odour of the oil are important aspects of quality.


Currently, there is not a standard for ‘therapeutic-grade essential oils’ (Guba 2004). However, some suppliers undertake independent quality-control tests to ensure essential oils meet aromatherapy requirements and to guarantee that their essential oils are:





In Australia most essential oils are listed in schedule 14 of the medicines scheduling system of the Therapeutic Goods Administration (TGA). However, TGA listing does not necessarily indicate benefit or efficacy, but does indicate that the risks associated with listed products are low. Manufacturers are not permitted to make therapeutic claims for listed products.


Aromatherapists prefer to use the entire essential oils rather than isolated compounds or synthetic oils, because the chemicals present in individual essential oils and blends have synergistic and quenching properties that enhance the beneficial effects and reduce unwanted effects. These beneficial interactions occur among the individual constituents within an oil and among the essential oils in a blend of oils (Clarke 2002, Price & Price 1995, Opdyke 1976). In most cases a blend of essential oils is used to suit the condition being treated, and the composition of the blend is modified according to the individual’s response in much the same way as herbal medicines are used. Common application/administration methods and doses are shown in Table 4.2 at the end of this chapter. Recommended doses are based on a long history of traditional use and the recommendations of experts, rather than on dose-finding trials. A number of factors need to be considered when deciding on an application method, dose and dose interval including:








Most aromatherapists do not recommend using fragrant oils for therapeutic purposes, although most accept they may have a role as environmental fragrances and may have psychological effects.


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Jul 18, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Introduction to aromatherapy

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