Essential oils are substances that contain the entire ‘core’ or ‘soul’ of a plant. The essential oil of a single plant can contain dozens or even hundreds of nature’s own chemical components that form a harmonious whole. It is not only the benefit to the skin of essential oils that is relevant: the fragrances can have mind-altering effects as well due to their biochemical ingredients and this aspect is one of the cornerstones of traditional natural cosmetics. Aromatherapy utilises these chemical components contained in essential oils, which are various aldehydes, phenols, alcohols and esters.
Aromacology, on the other hand, is a discipline based on scientific research methods and results obtained in laboratory studies. Aromatherapy is much more widely used in Central Europe than in the Nordic countries, and in France, for example, essential oils are also used internally under medical supervision. In this case, the oils must be chemotyped. A chemotype describes the chemical and biological properties of the plant and the molecules that the oil contains the most of and on which its effect is based. One plant can produce a wide variety of chemical components depending on, among other things, the growth conditions of the plant, which affect the therapeutic and toxicological properties of the essential oil.
Essential oils are mainly made by distillation, but some flowers, such as rose, jasmine and orange blossom, cannot withstand the heating that this process requires and thus their oils are extracted. The extraction solvent is then distilled at a low temperature to produce an absolute flower extract. Some oils, such as those from citrus, are made from the peel of a plant by pressing. The oil content of plants ranges from 0.01% to 10%: for example, one drop of rose essential oil requires the petals of 30 roses.
Individual fragrance components can also be isolated from essential oils. Some natural cosmetics brands perfume their products with such fragrance components. In this case, the aromatherapeutic and skin-care effects of the whole essential oil are lost. The principle of Djusie is that perfumes (INCI: parfum) are not added to the products separately, but that the scents of the products come from whole essential oils, as these make the products more caring for the skin. The following Djusie products contain essential oils: Liquid Silk Perfect Cleansing Oil and Fruit Glaze Vitalising & Brightening Facial Oil.
The ingredients of essential oils are also synthetically imitated in the cosmetics and pharmaceutical industries. An example is rose otto, which is one of the most precious essential oils in the world. It contains over three hundred different chemical components, including phenylethyl alcohol – an aromatic alcohol with a floral scent. Geraniol, on the other hand, smells like rose and is used in insect repellents, as is lemon-scented citronellol. Linalool, contained in lavender essential oil, smells of a spicy flower and has an anti-inflammatory effect, as does linalyl acetatella. These components can be found in many cosmetic products or household chemicals, even if they do not contain whole lavender oil or rose oil. From the perspective of aromatherapy, it is considered that the whole essential oil forms a harmonious whole that occurs in nature as such and that therefore the effects are based on this whole. If the whole is broken down, the aromatherapeutic effects may be lost and replaced by harmful or skin-irritating effects. For example, the sedative azulene from chamomile is more effective as part of the whole chamomile essential oil than as an isolated single component, and some aldehydes, in turn, can become harmful and irritating. Some people may also react to artificially made citral, but not to the whole essential oil of lemongrass. Nevertheless, if a fragrance sensitivity has been identified, proper care must always be taken with substances containing that allergen.
Some of the components contained in essential oils are classified as allergens/sensitisers, and these must be listed in the product’s INCI list in accordance with EU cosmetics legislation. There are currently 26 components classified as allergens, of which 16 are in whole essential oils. This does not mean that when a substance (e.g. geraniol) is listed separately from its essential oil (e.g. geranium essential oil) that it has been separately added to the product or synthetically produced.
The following allergens/sensitisers may be present in whole essential oils:
Benzyl alcohol
Benzyl salicylate
Cinnamyl alcohol
Cinnamal
Citral
Coumarin
Farnesol
Limonene
Eugenol
Geraniol
Isoeugenol
Anisyl alcohol
Benzyl benzoate
Benzyl cinnamate
Citronellol
Linalool
Essential oils should never be used directly on the skin in their undiluted form (there are exceptions for some oils, but this should always be checked) and when diluted, a dose of 0.5%-2% in a product for a healthy adult is appropriate, depending on the intended use. The use of essential oils comes with restrictions and properties that should always be checked before using them.