What are essential oils?

When you smell fresh roses or catch the fragrance of jasmine on the evening air, you are smelling the aromatic essence of the plant. Around 15% of flowering plants contain volatile oils, or essences, which release a strong scent. Press a sprig of rosemary or a bud of lavender between your fingers or squeeze the peel of an orange or grapefruit to release these volatile oils.

It is thought that the creation of volatile oils in aromatic plants is closely related to photosynthesis – the process by which plants absorb sunlight for energy and food. Plants release the volatile oils through specialised secretory structures such as cavities, ducts and oil cells. The volatile oils are used by the plant to attract pollinators, repel predators or even in plant warfare!

The volatile oils, or essences, of aromatic plants can be extracted from the flowers, leaves, stalks, fruits or roots (depending on the plant) by steam distillation. Only oils that have been extracted by the method of steam, or water, distillation are true essential oils. Oils extracted by methods such as solvent extraction are ‘absolutes’ (eg rose and jasmine). Oils extracted by mechanical expression remain chemically unchanged and are ‘essences’ (eg citrus oils).

What are carrier oils?

Essential oils contain highly concentrated chemical compounds and must be diluted in ‘carrier’ oils before direct use on the skin (eg massage, baths and showers, beauty therapy). Carrier oils are vegetable oils such as sweet almond, grapeseed or sunflower and are used to ‘carry’ essential oils to the skin. They are sometimes called ‘base’ oils because they form the base (main ingredient) of aromatherapy blends. It is important to use the correct dilution of essential oil:carrier oil to ensure that an aromatherapy blend is safe to use: guide to essential oil dilutions.