Essential oils to aid post-viral recovery of loss of sense of smell by Heather Dawn Godfrey

Relegated to background awareness while we amble through our daily life, viruses, for most of us, were mysterious, sometimes pesky, inhabitants of a distant domain – that is, until COVID-19 hit the worlds mainstream media headlines. Invisible to the eye, even smaller than bacteria, these infinitesimal particles, well, at least the notion of them, took the world by storm as they burst onto the stage.

Viruses, though, are not ‘new kids on the block’, nor, indeed, are they really, in spite of being invisible, backstage players.  Present since the dawn of creation, long before humans arrived on the scene, these invisible particles tirelessly play a vital and indispensible role in our evolution and our on-going ability to adapt, survive and thrive in natures ever-changing environment.

Even with the strongest electron microscope, these micro and nano particles are difficult to accurately decipher; microbiology, in truth, has only just left the surface in its Star Ship Enterprise to dive into this universe ‘where no man has gone before’.  According to the ships log, so far, it is known that viruses are extremely diverse and novel and, together with unicellular microorganisms, such as bacteria, fungi, archaea and protists, form one of the major components of earth’s intricate environmental web.  They exist throughout the global eco-system, and are even found in extremely bleak locations that otherwise appear devoid of life; for example, in salty and soda lakes, the Sahara Desert, freezing polar environments, hot acid springs, in the dark cold depths of oceans, even in nuclear radiation sites. (Le Romancer 2007, Russ 2007)

Viruses are not ‘alive’ in the usual sense, because they do not fulfill all the criterion of a living entity (movement, nutrition, excretion, respiration, reproduction, growth and sensitivity); they ‘host jump’ and borrow energy from cells.  For example, they apparently replicate rather than reproduce or divide, and in order to carry out this function they must first enter and tap into the resources of a suitable living host cell; thus, they appear to be parasitic.  

The qualities of essential oils

Essential oils are multi dynamic adaptogens; that is, they support the immune system and the body’s resilience to stress.  They stimulate the limbic system (the emotional brain), are antimicrobial, skin healing, hedonistic, and more.  They work simultaneously on each body system; so, simply, for example, an essential oil selected to add to a dry skin remedy, may also ease mild depression and/or uplift mood and emotion, while also sharing it’s antimicrobial qualities to avert infection.

All essential oils possess anti-viral and anti-microbial properties to varying degrees; they help protect the plant from pathogenic proliferation, which is one of the significant roles essential oils play within plants. Many essential oils inhibit and slow the growth of bacteria, yeasts and moulds.  Certain essential oil molecules (especially, for example, those found in eucalyptus, lemongrass, rosemary and tea tree} affect the lipid structure of bacterial cell membranes in a way that increases its permeability, causing the cell to lose ions and other cellular components, which leads to the cells death.   Some essential oils act synergistically, potentiating other anti-viral or medicinal agents, including biomedical antibiotics. (de Silver et al 2020, Nazarro et al 2013). 

How are essential oils detected?

Scent molecules (terpenes and terpenoids) are detected (like a key in a lock) by olfactory receptors located at the top of each nasal cavity that in turn relay nerve impulses to the Limbic System located in the brain. Odour receptors are also located in other parts of the body, for example, in the skin and other organs. However, by grand design, it seems, proximity of the master olfactory portal ensures immediate awareness and an instinctive reflexive response. Initially, protectively, we instantly decipher whether something is safe or noxious (do we accept or reject it?).  The sense of smell, however, is a complicated process, involving a number of neurological and psycho-emotional mechanisms.

Essential oils to support post-viral olfactory rehabilitation

Post viral anosmia (loss of the sense of smell) is not completely understood, especially when considering the complex mechanisms involved. Colds, influenza and COVID-19 are all corona viruses.  However, unlike common cold and ‘flu viruses, which have been around for thousands of years, COVID-19 is a new (novel) virus, apparently first identified in 2019 in Wuhan, the capitol of Hubei Provence in China.  COVID-19 is also highly transmissible.  Symptoms of infection range from mild to severe, depending on the age and health condition of the host.  In most cases people are not even aware they are infected; a high percentage (between 80 and 95%) of people experience no symptoms or mild ‘flu-like symptoms and recover without ill effect.  Some people, however, experience severe or acute symptoms (a chronic cough, shortness, chest tightness, shortness of breath, cognitive dysfunction and extreme fatigue), and in some cases these symptoms may linger for up to twelve weeks, or even longer (Post COVID-19 Syndrome). (Venkatisan 2021)  In instances of severe infection, where lungs and breathing capacity are compromised, direct olfactory inhalation of essential oils is not advisable, due to the risk of irritation and exacerbation of symptoms.

Loss of the sense of smell can occur in mild to severe cases of COVID-19, and may diminish without any obvious symptom of infection; up to 50% of people affected by COVID-19 report loss of their sense of smell.  Smell disruption occurs when virus particles attach to and penetrate the ACE2 coated cells that surround and provide structure and nutrients to the epithelium at the top of the nasal cavity in the roof of the nose.  Destruction of these cells leads to dysfunction of the epithelium which houses the hair-like olfactory nerves projecting from the olfactory bulb.  The sense of smell usually returns quite soon after recovery post infection, but sometimes it takes much longer, and sometimes the sense of smell is only partially regained and in a few instances never returns at all. (Rebholz et al 2020) 

Professor Thomas Hummel (ear, nose and throat expert at the University of Dresden, Germany) and colleagues trialed a simple, but seemingly very effective, olfactory re-training programme, applying four essential oils – rose, eucalyptus, clove and lemon – that were administered using ‘Sniffin Sticks’ (pen-like odour dispensing devices).   Participants sniffed each essential oil in turn for twenty seconds, in the morning and evening.  In a BBC interview (29th November 2018), Professor Hummel confirmed that forty five percent of people who apply smell training recover their sense of smell; compared with up to twenty two percent, who recover without intervention. Not all olfactory receptors, however, are repaired, which can result in alteration of the experience and perception of certain smells; for example, smells previously sensed as unpleasant may be rendered pleasing, and pleasant smells rendered displeasing, and so on. 

The qualities of the four essential oils selected for this training have capacity to stimulate the senses beyond simple scent detection activation.  Each scent is distinctive, and yet complex, revealing many layers and characteristics.  The sense of smell also influences tastes, and vice versa.  In Ayurveda and elemental modalities, for example, the taste (and qualities) of clove bud is aligned with bitter, and eucalyptus leaves with pungent, lemon with sour and bitter, and rose petals with sweet.  Bitter improves taste.  Pungent (a taste between sour and bitter) is associated with the lungs and immune system, and so on.  To be clear, I am not recommending the internal ingestion of essential oils here.

Collectively, these essential oils also stimulate the immune system, and may ease feelings of depression, grief, and anxiety and instil a sense of warmth, feeling grounded, clear-headed, and more.  For example, clove bud essential oil is antiviral, stimulates memory and eases depression; eucalyptus globulus is antiviral, and is mentally and emotionally bracing and clearing; lemon is anti-microbial, averts cold and ‘flu, and eases stress related conditions; rose alleviates coughs, and eases grief, bereavement and a sense of loss, and so on.

To learn more about what a virus is and how essential oils may aid post viral recovery, and more, please refer to my full article.

References

Russ, B., Dyall-Smith, M. (2007) Virus-host interaction in salt lakes.  Current Opinion in Microbiology 10(4):418-424. https://www.researchgate.net/publication/6124993_Virus-host_interactions_in_salt_lakes

Le Romancer, M., Gaillard, M., Geslin, C., Prieur, D. (2007) Viruses in Extreme Environments.  Environmental Science and Bio Technology.  https://link.springer.com/article/10.1007/s11157-006-0011-2

de Silva, J. K. R. (2020) Essential Oils as Antiviral Agents, Potential of Essential Oils to Treat SARS-CoV-2 Infection: An In-Silico Investigation.   International Journal of Molecular Science 21(10): 3426.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7279430/

Nazaro, F., Fratianni, F., Martino, L. D., Coppola, F., De Feo, V., (2013) Effects of Essential Oils of Pathogenic Bacteria.  Pharmacueticals (Basel) 6(12): 1451-1474.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3873673/

Venkatesan, P. (2021) Nice Guideline on Long COVD.  The Lancet, Respiratory Medicine, vol. 9 issue 2.  https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(21)00031-X/fulltext

Rebholz, H., Braun, R. J., Ladage, D., Knol, W., Kleber, C., Hassell, A. W. (2020 Loss of Olfactory Function – Early Indicator for COVID-19, Other Viral Infections and Neurodegenerative Disorders. Frontiers in Neurology.  Dementia and Neurodegenerative Diseases.

Damm, M., Pickart, L. K., Reimann, H., Burkert, S., Goktas, O., Haxel, B., Frey, S., Charalampakis, I., Beule, A., Renner, B., Hummel, T., Huttenbrink, K-B. (2014) Olfactory Training is helpful in post-infectious olfactory loss: a randomized controlled multicenter study.  Laryngoscope 124(4):826-31.  https://pubmed.ncbi.nlm.nih.gov/23929687/

Hummel, T. (2018) A simple flu, and simple infection: how effective is smell training at curing infection?  BCC News  interview.  https://www.bbc.co.uk/news/av/science-environment-46386497

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