What is an Essential Oil?
An essential oil is an organic liquid which is extracted from plant material. Because it is volatile (able to react), it emits an aroma when exposed to air, which is accentuated when warmth accelerates the evaporation of aromatic molecules.
Where do Essential Oils come from?
Essential oils are found in many different parts of the plant. The following list names some common essential oils and the part of the plant where they can be found – Sandalwood wood Geranium leaves Lavender *flowering tops Lemon fruit rind Rose, Jasmine flowers Juniper berries Frankincense gum Carrot seeds Ginger roots The term *flowering tops refers to the above-ground plant material harvested while the plant is in flower. Usually, there is only one essential oil in each plant. However, there are plants which have more than one essential oil in their different parts – fruit, leaves, flowers. The popular example is the Bitter Orange tree (Citrus aurantium) which has bitter orange oil from the fruit rind, petitgrain oil from the leaves, and neroli oil from the flowers. Not all plants contain essential oils. Of the many thousands that do, only around 200 essential oils are produced commercially for use. Essential oils are rarely produced solely for aromatherapy use. In fact, aromatherapy use accounts for less than 5% of the world oil production. The main uses are perfumes, food, fruit juices, alcoholic beverages, confectionary, cosmetics, pharmaceutical preparations, and everyday use items such as shampoos and soap. In some cases the complete essential oil is used (Bergamot in Earl Grey tea) and in other cases, one or more constituents are used (menthol from Peppermint oil). Geographic location
It is common for most brands of essential oils to say that their brand is the best. This statement implies that these brands have their own sources for their essential oils. The reality is that the best quality essential oils are often grown in specific geographic locations and are rarely owned by companies who have essential oil brands.
Here are some examples of the best quality essential oils and the specific geographic region in which they are grown and usually distilled –
Rose – Bulgaria and Turkey
Sandalwood – India (S. album) or Australia (S. spicatum)
Bergamot – Italy
Tea Tree – Australia
Rosemary – Tunisia (wild, CT cineole)
Are Essential Oils the same as the Plant (herb) they come from?
Essential oil actions are often assumed to be the same as the plant (herb) they come from. This is often not the case as the essential oil only contains some of the many constituents in the plant (see steam distillation notes). Therefore, the essential oil will only have some of the healing properties of the whole plant. However, because an essential oil is a concentrated extract from the plant, it is a more powerful substance and, unlike herbs, is only used in very small quantities (drops). The other consideration is the method of application. Herbs are often taken internally as a herbal tincture while essential oils are usually applied topically on the skin or aromatically. Many of the indications and contra-indications for essential oils were taken from herbal references and a great number of both indications and contra-indications have since proven to be incorrect.
Why is Plant Species important?
There are many different species or varieties of each plant. For example, there are several hundred different varieties of lavender. Only one or two specific species of each plant are cultivated for their essential oil. Generally, these species are not the ones you will find growing in your back yard or available from the local garden centre. The species of the plant is identified by the Latin botanical name written after the English common name (Lavender Lavandula angustifolia). Some plants share a common English name, but the botanical name will identify the plant species. Species identification is very important for aromatherapy as different botanical species of plants have different healing properties. Not only can a different species have different healing properties, it can have no healing properties at all and can even cause a problem if used. An example is Marjoram – one species provides an effective treatment for insomnia, another is likely to cause significant skin irritation and be mentally stimulating….hardly conducive to a good nights sleep. What are the physical characteristics of Essential Oils?
Understanding the physical characteristics of essential oils gives the buyer a better ability to choose a good quality product, and gives the user a greater ability to use them effectively in treatments. • They are not soluble in water. This is particularly important to note when using essential oils in baths. • Some of them are sensitive to UV (ultra violet) light from the sun (see contra-indications). • They are sensitive to heat. • They have a distinctive characteristic aroma which is subject to environmental conditions and to extraction conditions (see aroma). • They combine with other essential oils without losing their individual properties. This is called a synergistic effect. Often the combination of one essential oil with another will enhance or magnify a particular property. • Their consistency varies. Some are thin and runny like water (Lemon or Lavender) whilst others are thick and oily (Patchouli or Myrrh). Many will evaporate completely when placed on a tissue, and some will leave a stain or mark. • They blend easily in to carrier oils and cream bases.
Aroma
Pure essential oils for use in aromatherapy have distinctive characteristic aromas. Sometimes the aroma of an oil is the same as the aroma of the plant it came from, such as Lavender. Other times it is not. Rose essential oil is never as sweet as our memories of a rose bush would have us believe. There are many constituents that contribute to the aroma of the plant, not all of which are in the essential oil (see steam distillation). If you have become accustomed to particular aromas by smelling perfumed products such as cosmetics, soaps and perfumes, you may find the aroma of a pure essential oil not what you expected. The strength of an essential oil aroma does not determine the healing or therapeutic strength. Strong aromas are often caused by synthetic additives to give the impression that strong smell equals powerful properties. To further confuse the beginner, aromas are not just affected by the quality of the essential oil, but also by the country of origin, the time of the year and the environmental conditions.
How did the name ‘Aromatherapy’ come about?
The name itself is the cause of much confusion. Many believe that the therapy is in the aroma – that the smell of an essential oil will initiate the necessary processes to achieve a therapeutic result either emotionally or physically. This is only sometimes true. Obviously this belief has been the cause of much disappointment as you can hardly expect a fungal infection of the feet to be fixed by putting some Tea Tree and Myrrh in an oil burner. The man who started it all, R. M. Gattefosse and his word aromatherapie, apparently meant to convey the meaning that these therapeutic substances (essential oils) were also aromatic. Physical conditions such as wounds, burns, skin conditions, bacterial and fungal infections, do not rely on the aroma of the essential oils for efficacy, but the fact that they can encourage a positive mental state which must improve the healing process is a definite bonus.
How does Aromatherapy work?
Sense of Smell
To smell an aroma, we take in air through the nose by sniffing. The action of the air being drawn into the nasal passages draws in the aromatic molecules from an essential oil. These aromatic molecules are drawn up to the top of the nose where they make contact with the ‘smell receptors’ – hair like projections called cilia from special cells known collectively as the olfactory epithelium. This contact initiates a chemical process, which results in an action potential or message being sent via the olfactory nerve to several areas of the brain – the limbic system, the amygdala, and the frontal cortex.
At this point, we must rely on scientific theory as there is still discussion on exactly what happens when the aromatic molecules make that first contact. The prevailing theory is that the molecules form a pattern by binding to several different specific receptors. The receptors are believed to be different in size and shape, and can therefore only bind with molecules of a specific size and shape. However, any specific molecule can fit several receptors (The aromatic molecules are also thought to make contact with specific proteins in the epithelial mucosa thus altering or modifying their physical characteristics. These proteins are thought to have some influence in the contact process and therefore the initiation of the action potential or message). Thus any contact by aromatic molecules causes a ‘contact pattern’ and this pattern is chemically converted to a message for transmission to the brain.
The limbic system area of the brain receives the aromatic message which initiates a response which is automatic and does not require our conscious participation. The limbic system is the area responsible for our base or basic emotions such as fear, hunger, and sex drive – emotions that we feel instantly, automatically, without conscious thought, in response to some stimulus. An example of this is the feeling of hunger on smelling food cooking. The amygdala receives the aromatic message and, because it is part of the memory system, responds automatically with the recall of a memory – for example, ‘Lavender reminds me of my grandmother because she used to use the flowers for scenting clothing’. The aromatic message goes to the frontal cortex area of the brain for specific identification – for example, ‘I am smelling Lavender.’ This action may also have a mentally stimulating effect.
One point that science does agree on is that smells or aromas affect people emotionally. Nice or pleasant aromas cause positive emotions and unpleasant aromas cause negative emotions. A negative emotion can be changed to a positive emotion by a pleasant aroma.
Many years of experience have shown that certain essential oils invoke certain emotional responses in most people most of the time. This is believed to be due to their specific chemical constituents (esters are sedating, aldehydes are calming, alcohols are energising and stimulating, etc). Therefore by choosing a certain essential oil (or essential oil blend) for a specific person, we can be reasonably sure of a specific emotional response (Lavender is balancing, Clary Sage is euphoric, Lemongrass is stimulating, Rosemary for mental clarity, and so on). However, a person who has a negative memory of a specific aroma will probably have a negative emotional effect regardless of the anticipated influence of the essential oil based on its chemical constituents.
It is worth noting that a conscious thought can over-ride a sub-conscious response. In this instance, the essential oil will not have the desired effect if the recipient does not allow it to work by consciously rejecting the idea that the essential oil will have a positive effect.
Molecules of Emotion
There is a popular theory that human emotions are initiated and felt as a result of chemical molecular reactions. The emotion or feeling (say, sadness) is the result of a stimulus (say hearing or seeing something sad) causing a specific molecule to bind to a specific receptor (a protein on or in a cell) in enough numbers to produce the feeling or emotion. One chemical reaction happening in the body has the potential to initiate another chemical reaction. Therefore it is possible that in feeling a specific emotion, we are causing one or more physical actions to happen within the body – the cascade effect as can occur with hormones initiating further physical effects. This may be part of the explanation for ‘the will to live or die’, or for ‘the placebo effect.’ So it may also follow that smelling a specific essential oil will produce an emotional response which may, in turn, produce a physical response.
Topical Action
Essential oils are complex chemical mixtures (up to 300 different chemical constituents in one essential oil) capable of many different chemical reactions when introduced to chemically active areas. The surface of the skin is a chemically active area with natural enzymes, products placed on the skin, environmental factors, all contributing to the activity. Essential oils can kill bacteria (to prevent infection in wounds) and fungi (to resolve conditions such as thrush and athlete’s foot). Essential oils can act on skin tissue to promote healing in wounds and reduce scarring. They can significantly influence dry and oily skin conditions both superficially (the skin becomes nice to touch) and (apparently) by penetrating the dermal layer to alter and balance the sebum (natural oil) production in the skin.
These topical effects have nothing to do with the aroma (smell) of the oils and will happen whether the recipient believes in aromatherapy or not.
Internal Action
This would be the most controversial area in modern aromatherapy. There is no doubt that essential oils taken internally by mouth or via suppositories can have a specific significant effect. Many aromatherapists believe that essential oils can pass through the skin, are absorbed into the blood circulation and are delivered to specific locations within the body depending on the chemical constituents in the oil and on the disease or problem. They also believe that essential oils pass through the skin and act on specific tissue or organs located at (below) the site of application. This belief system is supported by indications (Peppermint for intestinal colic or stomach upsets applied to the abdominal area) that have apparently been known for many hundreds of years and are written in many texts.
The problem is that the original texts that quoted many of these indications were referring to herbal preparations which were generally taken orally. A herbal preparation and an essential oil from the same plant may share some properties, but they are different chemical substances and can have different properties. There is also a great difference in effectiveness due to the method of application. A herbal preparation taken internally can not have the same result as an essential oil applied via massage.
The potential of the skin to absorb (below the dermal layer) essential oils is also a contentious issue. One study claims to show that essential oils (or essential oil constituents as the essential oil starts to separate into its individual constituents as it passes through the skin) are absorbed into the blood stream via the skin as the constituents have shown up in the blood stream. This claim is contested by those who claim the essential oil constituents were absorbed via the nasal epithelium or via the lungs as the mouth and nose were not occluded during the study. Another study, using live skin taken from patients during operations, showed that Peppermint essential oil (and some of the individual constituents) took up to 72 hours to work its way through the skin layers potentially to the tissue below (there was no tissue below the skin in the study).
The skin can definitely absorb some substances as several drugs and nutrients are delivered via skin patches. Can the skin absorb essential oils and, if it does, do those essential oils deliver a predictable result? The skin can definitely absorb some constituents of some essential oils. But which ones are still to be determined and as for a predictable result – with the possible exception of a mild diuretic effect, we are still some way from making such a statement with certainty.
Energetic Response
All matter has a molecular energy and many people believe that essential oils have a powerful healing energy that interacts with the body’s energy. Some have suggested that the human body is ‘hot-wired’ to automatically respond to things such as essential oils – a nice (positive) aroma is good for me, therefore I will automatically respond both physically and mentally in a positive manner to something that I inherently know is good for me.’
Others have suggested that humans have a genetic bond with natural plant substances due to a generational bond that was made over millions of years of interaction – eating plants for food and using plants for medicinal purposes. Some believe in the energy of all things on the planet, and the ability of the different energies (plants, stones, water, humans, animals, etc) to influence humans emotionally and physically. There is widespread support for energetic beliefs that include chakras, auras, bush flower essences, gemstones and crystals, and reiki.
Many years of experience has shown that essential oils do have an energy that people respond to particularly well. They appear to have an immediate effect that can last hours, even days after one exposure.
Conclusion
So the final answer to the question ‘How does Aromatherapy Work?’ may depend on your belief systems. Aromas definitely effect emotions. Essential oils definitely effect the skin and some skin conditions. Essential oils can have a physical internal response depending on the route of administration, and they might have other physical responses by being absorbed through the skin. Essential oils do have an energy (all matter has a molecular energy) which might interact with and influence the human body’s energy.
Is it necessary to know how aromatherapy works? Is it not enough to know it works and simply embrace the results with joy? It is noted that those working in medical establishments concerned with questions of liability and insurance need to know. It is also noted that those working as intuitive therapists do not need to know.