Essential oils are natural aromatic substances extracted from plants. Although they are oil-soluble, they are strictly not ‘oils’ since they do not contain the fatty acids of a plant-derived oil. They consist of a mixture of compounds including alcohols, phenols, ketones and others. They have been used since ancient times by the Egyptian, Roman, Greek, Chinese and Indian cultures both in medicine and for their aromatic properties, although it is likely that they did not exist in the highly purified form in which they are used today. Essential oil production was refined during the last few centuries when the method of steam distillation was perfected. Today essential oils are used in aromatherapy, Ayurvedic medicine, the food industry, perfumery and natural skin care.
How are they made?
The most common method of extracting essential oils from plants is by steam distillation. This method involves passing steam through plant material, which vaporises volatile compounds from the plant. The resulting vapour is then collected and separated into the water fraction, which is termed a ‘hydrosol’, and the non water-soluble part which contains the essential oil.
The other 2 methods of extracting essential oils are ‘cold pressing’ and ‘solvent extraction’. Cold pressing is used to obtain the citrus essential oils – the oil is simply squeezed from the peel and then purified. In contrast, solvent extraction involves the use of chemicals to dissolve delicate compounds that would not survive the heat of the steam distillation process, examples being essential oils extracted from the petals of jasmine and neroli. The disadvantage of solvent extraction is that solvent residue almost always contaminates the final product, which is known as the ‘concrete’ or the further purified ‘absolute’. This is a particular problem when potentially toxic substances such as petrochemicals are used as the solvent. More recently a method known as ‘CO2 critical extraction’ was developed. This is considered a cleaner solvent for extraction of delicate essential oils, since at the end of the process the CO2 evaporates, and has the additional benefit of requiring no heat for extraction.
Irrespective of the method used, essential oils are highly concentrated plant extracts, each requiring different quantities of plant for their production. For example between 1,500-10,000kg rose petals are required to extract 1kg rose essential oil, making it one of the most expensive essential oils, whereas around 200kg lavender is required to obtain 1kg lavender essential oil.
What are the beneficial properties of essential oils?
Some of the compounds found in essential oils perform the same protective functions in humans as they do in the plant from which they were extracted, including antibacterial, antiviral, antifungal and antiparasitic and insecticidal properties. Many of the essential oils are considered to have these antiseptic properties, one of the best-known being tea tree oil.
A range of medicinal properties is attributable to various essential oils, and they are used in the practice of aromatherapy to treat conditions ranging from stress, anxiety and depression, through to arthritic pain and menstrual disorders. Because essential oils are potent, considerable knowledge of their use is required before considering their use to treat medical symptoms, and should be carried out under the guidance of a reputable aromatherapist. High quality, preferably therapeutic grade essential oils are generally used in aromatherapy.
In perfumery and skin care, essential oils may impart a state of well-being through their mood-enhancing effects – for example lavender has relaxant properties, helping insomnia and stress, rosemary and frankincense enhance the ability to concentrate and focus, whereas rose and the citrus essential oils are uplifting. There is considerable cross-over amongst the essential oils in their mood-enhancing effects, and essential oils may have synergistic effects when used in combination.
In addition, certain essential oils commonly included in natural skin care may also help with skin imbalances. These include enhancing oil production in excessively dry skin, for example, patchouli, frankincense and palmarosa, and reducing the production of oil in excessively oily skin, such as geranium and lavender. Others help combat the effects of acne, for example tea tree oil, while others supposedly reduce the incidence of wrinkles, such as frankincense and sandalwood.
A note on synthetic fragrances
After working with essential oils for a short period of time, the ‘artificial’ character of synthetic fragrances is clearly discernible to most people. They do not deliver the mood-enhancing and beneficial physiological effects of essential oils.
Although we discuss below the dangers of certain essential oils, it is worth pointing out the potentially greater hazard from synthetic fragrances, represented on product labels as ‘parfum’ or ‘fragrance’. It is possible to create a wide variety of fragrances from synthetic substances that cannot be obtained as an essential oil. These fragrances include strawberry, fig and honeysuckle. Synthetic fragrances are also manufactured to mimic the expensive essential oils like rose and jasmine. Because they are so much cheaper than essential oils, synthetic fragrances are used extensively in perfumes, cosmetics, toiletries, cleaners and air fresheners.
Unfortunately the synthetic ingredients used to make these fragrances result in sensitisation in up to 1 in 50 people, resulting in an allergic reaction with subsequent exposure, sometimes for life. In addition, they frequently contain phthalates, known hormone disrupters that have been associated with infertility, and some components are suspected of being neurotoxic. In addition, the synthetic musks used in fragrances are now also thought to be possible hormone disrupters.
Because of labelling laws, it is not possible to determine the constituents of synthetic fragrances. Despite this, synthetic fragrances are extensively used in common household products and in toiletries recommended for babies, children and during pregnancy.
Essential oils are extremely potent
In aromatherapy, essential oils are delivered most commonly by inhalation, although some essential oils may be administered orally. An alternative method of delivery is by application to the skin, since essential oils easily penetrate the epidermis, the outermost layer of skin, and from there enter the bloodstream. Because tiny quantities of essential oils act rapidly on the body, they need to be used in carefully measured quantities, and most cannot be safely applied to the skin unless diluted. Inhaling, ingesting or topically applying essential oils beyond the recommended dose may result in toxicity. Some commonly encountered problems are detailed below.
Some essential oils are known skin irritants, causing inflammation and itchiness when applied to the skin. This is seen most commonly in essential oils containing high levels of aldehydes or phenols. Examples include essential oils of cinnamon, clove, oregano and thyme, and these essential oils should never be used in topical applications.
Compounds known as furanocoumarins present in some essential oils are known to react with the skin in the presence of ultraviolet light, resulting in varying degrees of redness, and occasionally hyperpigmentation and vesicle formation. These compounds are present in high concentrations in citrus essential oils, the most potent of these being bergamot, as well as angelica root, lemon verbena and cumin essential oils. Topical application of skin care products containing these essential oils should be used with care, particularly when applied to skin that will be exposed to sunlight.
Some essential oils that are innocuous on initial contact with the skin produce irritation after repeated application. These essential oils induce an immune response which may result in redness, irritation and sometimes vesiculation following subsequent contact with the skin. Essential oils which are frequently implicated as sensitisers include essential oils of cinnamon, bergamot, clove and verbena.
Two components present in sassafras essential oil, known as safrole and dihydrosafrole, have been implicated in the development of liver tumours in rats, and so this essential oil is generally avoided.
Neurotoxicity and abortive properties
Essential oils containing high levels of certain types of ketones, oxides, or phenolic ethers when used above certain concentrations are considered to be both neurotoxic and abortive. These include essential oils of wormwood, sage, parsley seed, mustard, sassafras, pennyroyal, turmeric and numerous others.
Essential oils containing high levels of aldehydes may cause liver toxicity, particularly when taken over a long period of time or in high doses. Liver toxicity may also occur when essential oil components are metabolised into toxic chemicals.
Low doses of some essential oils that are considered to be stimulating and beneficial to the kidneys in aromatherapy may be toxic with excessive or prolonged use. Large doses of essential oils of savin, wintergreen, sweet birch and sassafras fall into this category.
Pregnancy, babies, children and sensitive skins
In addition to avoiding the potentially neurotoxic and abortive essential oils during pregnancy, most aromatherapists would recommend that essential oils be used at half the normal rate during pregnancy, since essential oils pass through the placenta to the foetus. As little is known about the effects of essential oils on the foetus, many people prefer to avoid exposure to essential oils during pregnancy, particularly during the first trimester.
Newborns are also vulnerable, and most aromatherapists would recommend avoiding exposure of babies younger than 3 months old to essential oils. After the age of around 3 months, lavender and chamomile essential oils are generally considered safe, and at later times certain other essential oils may be safely used in children.
Our approach to essential oils in skin care
Having worked with essential oils for many years, we are convinced of their beneficial effects both on the skin and on the psyche. However we have always taken the cautious approach, using them at concentrations of 0.5-1% in our skin care products, thereby reducing the risks associated with excessive exposure. We do not use the potentially harmful essential oils like parsley seed and cinnamon, and limit our use of potentially photosensitising essential oils like citrus to wash-off products, our bar and liquid soaps.
Over the years, a number of people have requested that we introduce a range of essential oil free products, mostly because they or their family members have extremely sensitive skins, or because they wish to be able to use our products while pregnant, or on their babies and young children. We are delighted to introduce our Essential Oil Free range, which we declined to call ‘fragrance free’ since they are naturally fragranced with the natural fragrances of the unrefined oils and butters they contain. Made with 100% certified organic ingredients, without preservatives or synthetic ingredients, they are the purest and mildest products you can find, suitable for everybody.