Many people are not aware about how essential oils pass through the skin. Generally people understand that they can end up in your bloodstream, but the mechanisms by which this happens are frequently not described in articles and books when actually it is very interesting!
As we know, the skin forms an awesome barrier between us and the world. It holds all our internal organs together, keeps many chemicals out and forms a first defense against everything our environment throws at us. Nonetheless, it’s not impervious and many chemicals penetrate our skin to various degrees.
Essential oils are different because they have a much smaller molecular weight and therefore pass through the skin. When the molecular weight of an ingredient is under 500 Dalton (the standard measurement unit of atomic mass) then it is thought to be able to freely pass through the top layer of the skin, the stratum corneum. All essential oil components have molecular weights well under the 500 Dalton mark so they pass with relative ease.
The outer part of the skin, the epidermis, consists of different layers which are partly oil-loving (lipophilic) and partly water-loving (hydrophilic) which is why so many individual ingredients struggle to get past this barrier because they are generally one or the other and not both at the same time. However, essential oil constituents have an affinity with both oil and water (predominantly oil) which means that they find it easier to pass through the outer barrier of the skin.
In 1940 a researcher called Straehli did some fascinating tests on essential oils. He found that all the oils tested appeared in his subjects’ breath following absorption through the skin (Tisserand & Balacs, 1995). In other words, the essential oils penetrate into the skin, make it into the bloodstream, diffuse all around the body to various organs including the lungs and are then breathed out.
Straehli found that different chemicals and their constituents were breathed out at different time intervals:
- 20-40 minutes – eugenol and linalool (these chemicals are components of many common essential oils including cinnamon and rose).
- 40-60 minutes – anise, bergamot and lemon.
- 60-80 minutes – citronella, lavender, geranium and pine needle.
- 100-120 minutes – coriander, peppermint and rue.
This study, and others that have been undertaken since then, show that essential oils certainly do make it into the bloodstream – and much further than that.
Initially an essential oil goes to areas of high blood flow such as skeletal muscle, the liver and kidneys. It may become absorbed into the fat tissue. However, it is thought that an essential oil does not stay in circulation for a long period of time. Eventually it is excreted through the kidneys in the urine, exhaled by the lungs, secreted through the skin or passed through in the feces (Clarke, 2008).
Everyone’s skin and surroundings are different and every essential oil is different so clearly there are lots of different factors affecting absorption. Essential oils evaporate quickly when applied to warm skin so you will always find that a percentage disappears before it has the opportunity to penetrate the upper layers of your skin. However, warm surroundings enhance penetration of essential oils so a hot bath or a warm massage oil (or even warm hands!) increase the rate of penetration significantly, probably because of the increased blood flow caused by an increase in temperature.
Certain essential oils are more viscous than others and this will also affect penetration – the more viscous, the slower the rate of penetration. Covering the skin with a non-permeable material will also significantly increase essential oil absorption into the bloodstream.
Essential oils are potent little chemical compounds and can help with a myriad of different skin and bodily problems.
Excerpts taken from: Can Essential Oils Get Into your Bloodstream: Lorraine Dallmeier