In the aromatherapy world, inhalation through the lungs is the most widely accepted theory of how essential oils work. This has little scientific proof, however. Methods of inhalation include tissues, hands, baths, sprays, diffusers and vaporizers. Firstly, the nose inhales the essential oils. The essential oil aroma then passes through the respiratory system and finally a gaseous exchange takes place in the lungs, diffusing the essential oils.
Conversely, olfaction (the sense of smell) is the most widely accepted theory by scientists on how essential oils access the body. This is the only sense which has a direct link to the brain, chemically converting the essential oil aroma in the nose and relaying the information to the brain. Electrochemical messages are sent to the appropriate part of the brain, triggering the release of neuro-chemicals and causing subsequent effects.
Absorption through the skin
There is a dispute in the scientific world over whether this theory works but a study carried out by Jager et al (1992) states that when applied in a base oil, essential oils are absorbed into the bloodstream. Some essential oils, with very small molecules, may directly penetrate the skin and pass through sweat glands and hair follicles to reach the uppermost layer of skin and capillary circulation. They are then absorbed into the blood stream.
The skin is a poor barrier to fat-soluble substances allowing essential oils in a carrier oil to be applied to the skin and absorbed into the blood stream by a process of simple diffusion. Fat soluble particles of essential oils dissolve in the oily sebum, produced by sebaceous glands, and pass into the deeper, second layer of the skin. They are then carried by the blood and lymph vessels into the main blood stream.
'Top note' essential oils, such as Lemon and Orange, will be absorbed more quickly into the skin as they have smaller, lighter molecules. 'Base note' essential oils, such as Rose and Patchouli, will take longer. Absorption rates may also be affected by heat, massage, condition of the skin and breathing rate. Methods of application include compresses, sprays, baths and topical application such as massage.
Ingestion of Essential Oils
Although ingestion is a very common method of using essential oils in France, by both aromatologists and doctors, it is not a method that is widely used elsewhere in the world. Research carried out by medical aromatologists in France shows that every drop of the essential oil reaches the systems of the body.
Knowledge of the constituents of essential oils is of extreme importance when using this method and it is not recommended for use in the USA. Things that should be known include the longevity of time over which it should be taken, concentration strength and the characteristics of any diluent used. There is the potential for toxicity if not used correctly.
In summary, essential oils enter the body in a number of ways and the effectiveness and validity of each method is hotly disputed by scientists. New research continues into discovering how essential oils work; meanwhile aromatherapy and the use of essential oils continues to rise in popularity around the world, indicating that, however it works, people are recognizing the value of essential oils in today's modern world.
References:
Price, Shirley, Price, Len 1999 Aromatherapy for Health Professionals Edinburgh: Churchill Livingstone
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