Heather Dawn Godfrey P.G.C.E., B.Sc.
Author of Healing with Essential Oils, Essential Oils for the Whole Body, and Essential Oils for Mindfulness and Meditation (winners of the Janey Loves Platinum Awards 2019 and 2018) – published by Inner Traditions, Bear & Co., Vermont USA
The following article includes excerpts from Healing with Essential Oils
This article explores the role of essential oils in aiding recovery of the loss of sense of smell after a viral infection, such as a cold, or ‘flu, and more recently COVID-19 (SARS viruses – severe acute respiratory syndrome). The content is divided into three parts in order to contextualise each element:
- What is a virus?
- The related properties of essential oils.
- Essential oils to support olfactory rehabilitation.
What is a virus?
Relegated to background awareness while we amble through our daily life, viruses, for most of us, were mysterious, apparently 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, in deed, are they really, in spite of being invisible (or rather, too small to see), backstage players. Present since the dawn of creation, long before humans arrived on the scene, these nano-particles tirelessly play a vital and indispensable 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, viruses 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)
In spite of being infinitesimally small, viruses are believed to influence global biochemical cycles and drive microbial evolution. Many viruses are strain-specific predators (or host hunters). They kill off microbial pathogens and strains to prevent species dominance in a given environment, especially within oceans, thus maintaining microbial balance. For example, as a particular microbe strain becomes dominant it’s viral predators will expand in number exponentially and kill the microbes off, leaving a niche for another microbe strain to grow into, which will subsequently be killed off by another viral type.
As viruses move throughout the world they exchange vital genetic information between hosts and ecosystems, fulfilling commensal and mutualistic roles; in deed, the vital relationship virus’s share with and between animals, insects, plants, the environment, and other microbes and viruses, is intricate, complex, and often vital. (Rohwer et al 2009)
Thus, viruses are symbionts that operate on a continuum from pathogenic to mutualistic, depending on environmental conditions. Just as they do in the depths of the ocean, viruses play a significant role in managing and maintaining balance and harmony within our body. In deed, most viruses are present within all of us, living in dynamic equilibrium with our immune system; according to Professor Herbert Virgin (2013) we literally live in a ‘sea’ of viruses.
There are apparently at least a thousand different virus species (or rather, types, as they are not alive) present in the human body, collectively numbering in the hundreds of trillions (some estimate three hundred and eighty trillion); known en masse as the human virome. By comparison, there are an estimated ‘mere’ thirty-eight trillion bacteria inhabiting the human micro biome. Viruses, bacteria and other microorganisms are found on our skin and within a microscopic aura surrounding our body, around and within orifices, within organs, including the brain, and especially within our gut, where they aid food digestion and vitamin production (for example, vitamin K, B12, thiamin, and riboflavin – bacteria help produce vitamin C) among other things. They help to set up our immune systems when we are young; exposure to infection helps the immune system build up a ‘database’ of information, an armoury that protects us later in life. Healthy humans also carry a number of novel, unknown, viruses, including bacteriophage (viruses that paralyse a bacterium by infecting it and replicating inside) to known human disease-causing pathogens – the impact of these novel viruses is yet unknown. (Sayer Ji 2021, Roossinck 2015)
Just to clarify a small point before I continue; some authors refer to viruses and bacteria collectively as microorganisms (organism refers to a living thing) while other authors make separate distinction between the virome (consisting only of non-living viruses) and the micro biome (consisting of living bacteria, fungi and archaea – primitive single-celled organisms).
But, really, what are they?
Simply, a virus is a particle of genetic RNA (assembled in the cytoplasm of a cell) or DNA (constructed in the cells nucleus), which is surrounded by a protein coat (capsid) that may or may not be surrounded by a further lipid membrane envelope.
Viruses are not ‘alive’ in the usual sense, because they do not fulfil all the criterion of a living entity (movement, nutrition, excretion, respiration, reproduction, growth and sensitivity); apparently they ‘host jump’ and borrow energy from cells. For example, they 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.
Once inside a cell, and after attaching and transferring it’s genetic material into a host cell, the original virus particle replicates its DNA or RNA and protein cover thousands of times, creating, or rather assembling, new virus particles. This process of replication continues until the cell literally bursts open, expelling the newly formed particles, which then go on to infect other nearby cells, thus perpetuating replication; cell infection can occur over a few hours or several days depending on the type of virus.
However, there is another proposition emerging from the Star Ship Enterprise log.
According to Dr. Robert Young (2021, 2020), viruses do not invade cells but are toxic exudes excreted from cells; waste products finding their way out of the body. They are the expressions of disease and instigates symptoms usually attributed to infection (such as, raised temperature, sweating, excessive mucus, diarrhoea, aching muscles, headaches and so on); viruses are the means by which the body rids itself of toxic waste (this waste also includes debris from bacteria cells). Viruses also act as messengers (Sousa 2020).
Viruses are included within an infinite range of particles found in and around cells – including, among others, bacteria, exosomes and microscopic helminthes – a veritable soup. Bacteria are the biological breakdown products of cells and, unlike viruses, comprise of genetic matter. Bacteria behave as ‘scavengers of nature – they reduce dead tissue to its smallest element’ – they clean up the territory. Exosomes are discrete expressions, messengers, from cell repair proteins; they are virus-like particles that are sometimes indistinguishable from viruses. Helminths are worm-like parasites.
Both viruses and exosomes are information delivery systems, and this is one of the reasons they may be confused with each other. However, exosomes are non-specific information messengers and can be absorbed by any cell, whereas viruses are highly selective and will only target specifically designated cell receptors (like a key in a lock). In the case of COVID-19, for example, it is the ACE2 receptor expressed in the lungs and other tissues of the respiratory and vascular system.
Dr. Zach Bush (2021, 2020) similarly describes viruses as being non-living vectors, or carriers, of genomic information secreted from bacteria, fungi, multicellular plant life, humans and animals, which are released, or activated, in response to stressors; thus, signalling need for adaptation (to regenerate or detox, for example) to environmental threats or changes. If life is peaceful, Bush explains, and there is no immediate threat or disturbance, then there is little need for the expression of virus exudation from the body. Dis-ease is a consequence of stress, which can have various causes; for example, environmental pollution, chemical toxins in foods (herbicides, pesticides, chemical additives etc.) and household products, poor living and working conditions, an impending sense of scarcity and threat, and so on.
Viruses convey new information to the body (or organism); we are not in conflict with the virome, the virome does not exist to attack us, but to inform and assist our regenerative and adaptive capacity within an ever-changing environment. The micro biome plays its own role. New science, for example, says Bush, reveals how the micro biome guides our health and ‘functions as the life-giving soil within our gut and internal organs, and is at the core’ of our ability to thrive; thus we survive by virtue of the intelligence of nature, which, saturates, connects and communicates with all life through the micro biome. The internal endogenous (of internal origin) and external exogenous (of external origin) virome and micro biome are intrinsically interconnected.
‘Germs are nothing, terrain is everything’, Robert Young affirms (2020). If the terrain is compromised and overburdened with toxins, or otherwise stressed and/or weak, then things may go awry. A clean terrain is the foundation of healthiness (‘cleanliness is next to godliness’ he reiterates). Viruses, exosomes and bacteria are products, or helpers, of the body’s attempt to cleanse, repair and maintain healthy equilibrium and function:
We do not catch diseases. We build them with what we have to eat, drink, think, fear, and believe them into existence. We work hard at developing our diseases. We must work just as hard at restoring health.
The presence of germs (viruses, bacteria, yeast, mould and their associate exotoxins, endotoxins and mycotoxins – acids) does not constitute the presence of sickness or disease. Germs or bacteria have no influence, what so ever, on living cells – they flourish as [cleansing] scavengers at the site of disease.
Whichever way you look at it, it seems to make sense that the condition of the body’s terrain contributes in some way to our resilience and functional equilibrium. According to Young, a body filled with unclean toxins and waste particles indicates decay, which initiates bacteria to ‘clean up’, as ‘scavengers of nature – to reduce dead tissue to its smallest element’.
Sayer Ji (2020 p 52-3) reminds us:
Our bodies resemble plants in that our susceptibility to pests, or opportunistic infections, escalates when we aren’t provided with the proper inputs, such as when our ecosystems are in a state of disharmony, when our microbial soil is depleted, and when our micronutrient status is compromised. The modern pressures of a sedentary lifestyle; pharmaceutical drugs; occupational stress; ultra-processed foods; electromagnetic pollution; man-made toxicants; and circadian rhythm-disrupting blue-light cause our micro-diversity to suffer, in turn opening the door to sickness.
When we malign all bacteria as microorganisms to be feared and eradicated, we indiscriminately target commensal and virulent microbes alike. We do so with antibiotics, hand sanitizers, chemical cleaning agents, triclosan-laden antibacterial soaps, and gut disrupting pharmaceuticals like acid-blocking drugs and over-the-counter pain relievers. While they are purportedly designed to heal, these prescriptions inevitably destroy the system that has evolved to protect us.
Our health and resilience is determined by multiple factors, and once we are aware of these, we can take steps to maintain, balance and manage our bodily terrain. We are not simply the random victims of these invisible inhabitants. When we take care of our body (keeping it toxin free, clean and nourished, observing what we absorb into our bodies – fresh nutritious foods, fresh air, clean water, positive thoughts and emotions, optimism and positive community) we also provide a thriving healthy symbiotic territory for trillions of invisible microbes and particles, and are consequently more inclined toward resilience and resistance to disturbance and pathogenic invasion, thus improving our opportunity to move through life unimpeded by illness and disease.
The Immune System
The immune system works in harmony with the body’s micro-biome and virome.
The immune system is a complex network of cells and proteins (cytotoxic T Lymphocytes, natural killer cells, anti-viral macrophages) that defend the body against pathogenic infection and systemic harm or imbalance. The innate immune system provides initial ‘front line’ protection; however, while fast acting, it is non-specific in its action. The adaptive immune system, on the other hand, instigates more specific honed responses, which are not always immediate. Helper T Cells, for example, recognise pathogenic infected cells (foreign or toxic particles, or bacteria) and produce cytokines (a hormone-like protein) that attach to the infected cell, then triggers or stimulates specific responses by target cells, or anti-bodies. Antibodies (a unique Y-shaped protein made and mutated within the body) are produced and employed by the adaptive immune system to recognise and neutralise pathogenic bacteria, other microbes or particles (antigen); once produced, these antibodies remain in the body for some time. The adaptive immune system records each pathogen ever defeated, so recognises it quickly again and destroys it. (Schrader 2015)
How do essential oils support resilience?
The related properties 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 are capable of independently and simultaneously influencing various body systems; 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 anti-microbial qualities to avert infection.
All essential oils possess anti-pathogenic and anti-microbial properties to varying degrees (one of the significant roles essential oils play within plants). They help protect the plant from pathogenic proliferation among other roles. Their actions are targeted and do not harm the terrain. Many essential oils, for example, inhibit and slow the growth of pathogenic 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).
Some essential oils possess broad-spectrum bactericidal and anti-viral qualities, while others are more specific in their action, depending on the chemical composition of the essential oil and the type of microbe or viral particle; broad-spectrum in this context does not mean a single essential oil or blend of essential oils will kill or disrupt all pathogenic viruses or all bacteria. Some essential oils also stimulate the immune system and the body’s self-regulatory process. (Vasey 2018) (see fig 1.)
Essential oils may act preventatively, averting pathogenic invasion, and appear especially useful during the early stages of infection. They support the immune system by promoting activity of lymphocytes (immune supporting white blood cells), increasing phagocytosis (the process by which an immune cell uses its plasma membrane to engulf large particles, such as viruses or an infected cell), and induce interferon production (interferons are signalling proteins that ‘interfere’ with viruses to prevent them from multiplying). (Sandner 2020, Han 2017, Kuriyama 2005) They also ease symptoms, such as those associated with colds and ‘flu; for example, headaches, nasal and sinus congestion, cough, muscle aches, and other symptoms such as insomnia, depression and anxiety.
Significantly, unlike conventional antibiotics, essential oils do not appear to negatively disrupt balance of the body’s micro biome. However, this is not to say they are not capable of doing so or that the immune system will not develop resistance (or over react) to essential oils or their components. It is true that the molecular complexity of essential oils may delay resistance to them, but this delay is undone if essential oils are repeatedly overused or inappropriately applied (see Godfrey 2019 Essential Oils for the Whole Body, and Tisserand and Young 2014 Essential Oil Safety, for further information about safe and appropriate application of essential oils)
Essential oils and the sense of smell
When we smell and acknowledge the scent of a flower or a fruit, even the scent of the soft skin of a newly born infant, we are responding to messages instigated by odour molecules permeating our immediate environment. Neurobiologist, Leslie Vosshall, of Rockefeller University (New York), estimates that the human nose, which has 400 hundred different types of scent receptors, can distinguish an average of at least one trillion different odours (in a range from 80 million to a thousand trillion)! (Williams 2014).
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.
The Limbic System incorporates various functional structures located in the central paleomammalian part of the brain (including the amygdala, hippocampus and hypothalamus) that are responsible for basic physiological and emotional responses to sensory stimulation. The hypothalamus functionally connects the Limbic System to the frontal lobe (where the brain rationalises and makes sense of information and sensory input) and the pituitary gland. The pituitary gland, also known as the master endocrine gland, initiates hormone release in response to sensory signals, activating either the sympathetic or parasympathetic nervous system. Depending on the nature of the stimuli, the sympathetic nervous system prepares the body for ‘fight or flight’ (protection), and the parasympathetic nervous system maintains a state of peace and relaxation (rest and digest), and disengages the sympathetic nervous system post ‘alert’, returning the body to its optimal functional resting state. (Godfrey 2019)
The trigeminal nerves also play a part in odour detection, lending sensation to the sense of smell (for example, hot, cold, tingling, even irritating). Menthol found in minty essential oils, for example, produces feelings of cold at moderate concentration but feelings of heat at high concentration. Trigeminal nerve receptors add sensation to the experiential dynamics of odour perception, whether subtle or obvious, and play a role in the complex process of odour detection, identification, and consequential neuro-physio-psycho-emotional stimulation. Around 70 per cent of all odorants stimulate the trigeminal nerve receptors to varying degrees (Leffingwell 2021, Godfrey 2019, )
Essential oils to support olfactory rehabilitation.
Post viral anosmia (loss of the sense of smell) is not completely understood. The sense of smell is a complex process involving various nervous and brain system mechanisms; response to scent is often instinctive and reflexive.
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 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, and a high percentage (80 to 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) A note of caution: 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.
Corona viruses, in general, cause symptoms that include fever, chills, body aches and coughs. In the case of colds and ‘flu, Inflammation causes the nasal passages to become swollen, which hinders odorant molecules from reaching the corresponding receptors in the epithelium and binding with these, thus reducing ability to detect smells, especially the various nuances of odour. Airflow, due to nasal congestion, is also reduced, and, therefore, the quantity of odorant molecules available for detection is limited. The olfactory epithelium and connecting peripheral nerves may also be damaged, thus obstructing neural signaling to the olfactory bulb and organs of the limbic system, where scent signals are detected.
COVID-19, however, does not appear to instigate ‘cold-like’ symptoms (sore throat, nasal swelling and mucous congestion), but does produce symptoms of fever, a dry cough, and shortness of breath (as above). COVID-19 virus particles interface with ACE2 receptors. Angiotensin converting enzyme (ACE) is a protein that coats the surface of many cell types, and acts to prevent cell damage and death. While ACE receptors are expressed in almost all tissues, ACE2 is particularly expressed on alveoli epithelial cells, capillary endothelial cells, cardiovascular cells, and cells within the brain.
In severe cases of infection (in most incidents the immune system prevents development of serious infection progressing from the upper respiratory tract – nose and throat – to the lungs), COVID-19 virus particles damage the alveoli in the lungs after binding with ACE2 receptors on the cells surface, entering and destroying the cell, causing severe breathing difficulties and other pneumonia-like symptoms. Infected and damaged alveoli seriously impede gaseous exchange, reducing cell oxygenation, which causes buildup of carbon dioxide in the body, cell deterioration and, eventually, organ deterioration (lungs, liver, kidney, heart, pancreas, intestines and brain). In rare cases there is no immediate obvious sign of lung infection. (Ni et al 2020)
In terms of disrupting the sense of smell, COVID-19 virus particles attach to and penetrate supporting ACE2 coated cells that surround and provide structure and nutrients to the olfactory epithelium at the top of the nasal cavity, hijacking and destroying these cells, causing dysfunction of the epithelium and the hair-like olfactory nerves projecting through the epithelium from the olfactory bulb. Sometimes the sense of smell diminishes without any other obvious symptom of infection. Up to 50% of people affected by COVID-19 report loss of their sense of smell. The sense of smell usually returns quite soon after recovery from infection, but for some it takes much longer; sometimes the sense of smell only partially returns or is never regained. Some pathogens, including viruses, may enter the higher brain region via the epithelium and olfactory nerve portals (Rebholz et al 2020)
Applying essential oils as aids to regain the sense of smell after viral infection
Professor Thomas Hummel and colleagues (Damm et al 2013, Hummel 2009) devised a system of re-training olfactory receptors after the loss of the sense of smell, using four essential oils (rose, eucalyptus, clove and lemon) to stimulate, growth of olfactory receptors and epithelium supporting cells at the roof of the nose. In a BBC interview (29th November 2018) Professor Hummel (ear, nose and throat expert at the University of Dresden, Germany) confirmed that after deliberately sniffing each essential oil for twenty seconds in the morning and evening, using Sniffin Sticks (pen-like tubes containing the oil, held just at the entrance of each nostril) as a delivery mechanism, 45% of those tested recovered their sense of smell, whereas only 22% of people recovered without smell training. Some people experienced change in their perception of odours, attributed to the fact that not all receptors were recovered; this sometimes resulted in alteration in the nuances of some smells.
This experiment was recently repeated by Professor Claire Hopkins, President of the British Rhinological Society and Consultant Ears Nose and Throat Specialist, who described the process in an interview for Sky News (8th January 2021) as ‘physiotherapy for the nose’, a form of exercise that stimulates nerve recovery and reestablishes connection within the brain. Using the same four essential oils, Professor Hopkins described how the essential oils are ‘dropped’ onto a small pad in a jar. Removing the lid, each of the four jars is held to the nose in turn and sniffed for twenty seconds two or three times a day. Professor Hopkins confirmed this process enhanced the rate of long-term recovery considerably. She also observed some changes in the sense of smell post recovery, sometimes in ways that improved the odour perception.
Essential oils exhibit capacity to influence more than one element of the body at the same time, and sometimes demonstrate a synergistic effect (with each other and other chemicals). Therefore, not only do their scent molecules stimulate the sense of smell (and an emotional response instigated via olfactory connection with the Limbic System), they also stimulate anti-inflammatory, anti microbial, anti-viral, and tissue healing and regenerating responses. In deed, the essential oils applied in the above smell recovery programmes (rose, eucalyptus globulus, clove bud and lemon) demonstrate, among other qualities, anti-viral and antimicrobial properties, especially clove and eucalyptus (fig 1). Therefore, as part of the process of smell recovery, it is likely that these oils equally support the immune system reestablish microbial balance and also aid tissue regeneration.
Asif et al (2020) reviewed research (computer-aided docking and in vitro studies) exploring ‘COVID-19 and therapy with essential oils that had antiviral, anti-inflammatory and immunomodulatory properties’. They propose in conclusion that essential oils do have activity against SARC-CoV-2, but recommend further in vitro (lab) and in vivo (life) studies to establish the safe dose and clinical efficacy of essential oils. The essential oil components found to demonstrate anti-viral actions were menthol (found in mint oils and geranium), eugenol (found in cloves) carvacrol (found in oregano, wild marjoram and thyme), cinnamaldehyde (found in cinnamon bark and cassia bark), geraniol (found in wild bergamot, palmarosa, lemon thyme, and geranium), 1,8-cineole (found in eucalyptus, cajeput, and Spanish marjoram) and L-4-terpineol (found in tea tree).
In another review exploring the potential for essential oils to treat SARS-CoV infections, de Silva et al (2020) found, out of 171 essential oil components scrutinized, (E,E)-alpha-farnesene, (E)-beta-farnesene, and (E,E)-farnesol (found in German and Moroccan chamomile and rose) demonstrated the best, although weak, anti-viral potential against SARS-CoV infections . They acknowledge, however, that essential oil components may act synergistically and that essential oils may potentiate other anti-viral agents. They also acknowledge that essential oils may provide some relief from symptoms of COVID-19.
The antibacterial, anti-fungal and anti-viral properties of essential oils are well evidenced (see fig 1). Viruses, though, constantly mutate or recombine with other viruses, so their presentation is in perpetual flux; predominant strains of ‘flu viruses, for example, vary from season to season, necessitating perpetual annual flu re-vaccination programmes in response.
Fig. 1. Essential Oils that have demonstrated anti-viral and anti-microbial properties
Australian Sandalwood – (E,E)-farnesol
Marjoram (wild, Spanish)
Melissa (Lemon Balm)
Cinnamon (bark, leaf)
Cell-death (membrane penetration, reproduction inhibition)
Cinnamon bark (cinnamaldehyde)
Cinnamon (bark, leaf)
Clove + Rosemary
Sandalwood (Australian) + Myrrh
Sandalwood (Australian) + Vetiver
Frankincense + Myrrh
An essential oil can comprise of a mixture of at least a hundred to several hundred organic chemical components in variable quantity and combination, depending on the type of oil. The chemical composition of an essential oil is influenced by factors such as plant species, geographical location and environmental conditions of growth, the age of a plant, and so on. These factors (including how fresh an essential oil is at the time of use, conditions of storage, rate of oxidisation and so on) influence the chemical composition and potency of essential oils. For example, lavender angustifolia harvested and distilled in northern France and tested within a week will differ in composition from lavender angustifolia harvested and distilled in Spain, or the UK, and from lavender oil tested six months or twelve months after distillation, and so on. So many variables to pin down that are not always acknowledged in study results.
Additionally, in terms of applying essential oils as a treatment for COVID viruses and viruses in general, the timing of intervention from the onset of infection is also significant. For example, Shi et al (2020) recommend that, in the case of COVD-19, the immune system be boosted during the first and second stage of infection, when there is better chance infection will be more easily contained and controlled, but should be suppressed during the inflammatory phase when the virus has reached the alveoli in the lungs; at this stage, oxygen uptake is critical and can be negatively compromised by over reaction of the immune system.
Essential oils exhibit preventative potential (Kumar 2020), although effectiveness also depends on general background health (comorbidities and an already compromised immune system significantly influence predisposition to infection and may prolong the rate of recovery). The preventative qualities of essential oils are enhanced when combined with other preventative strategies (and vice versa), such as, exercise, fresh air, an unprocessed, fresh, organic diet, and vitamin and mineral intake. Vitamin C, for example, was applied in Wuhan and New York hospitals during the initial outbreak of COVID-19 last year, and demonstrated some supportive success (Zuo 2020, Hemila 2003); high doses of vitamin C modify susceptibility to various bacterial and viral infections. Vitamin D3 regenerates endothelial lining in blood vessels and is shown to minimise alveolar damage (Kakodkar et al 2020). Vitamin B3 is highly lung protective and may be useful at the onset of coughing (Shi et al 2020). Zinc reduces inflammation and boosts the immune system. Vitamin A helps the lungs, heart, and kidneys, and other organs, function properly (Ayyadurai 2020). Low dose of Hydroxychloroquine is also reported to quickly alleviate symptoms (and also to act as a preventative), especially when taken during the early phase of infection (Professor Dolores Cahill 2020). These strategies will also support the body to recover from infection.
Then, there is the psycho-emotional and subjective phenomenological influence of essential oils; for example, the influence essential oils have on the limbic system; memory, mood and emotion (Godfrey 2019, 2018), also the trigeminal nerves in terms of sensation (Leffingwell 2021). The boundaries between physical, psychological and emotional (body, mind, and spirit) often overlap. Indeed, feeling happy, relaxed and calm, positive and optimistic demonstrably influences physical function; heart rate, blood pressure, cortisol levels, endorphin release, digestion, and so on. Attitude, taking control, responsibility, for one’s health and wellbeing (which is a form of positive optimism) also influences outcomes (Godfrey 2020, Gao et al 2017, Conversano 2010).
Stephanie Feuer (2019), in her article ‘How I bought my nose back to life’, eloquently shares her own journey of smell recovery, poignantly describing how she felt removed from the world in an impenetrable bubble as if swathed in cotton wool, where she grieved her loss of sense of smell. She tried everything from vitamins, herbal remedies to working out, even running up and down stairs in attempt to jog her sense of smell to life, to no avail. Then, learning about smell training, she set up her own ‘home made’ version, dropping essential oils on paper. “I didn’t smell the eucalyptus, but I could feel it.” Diving into her imagination, she conjured up vivid images, drawing on memory to capture the context and experience associated with smells that delighted her, sensually immersing in the colours, textures and emotions evoked. “I squeezed my eyes and tried to focus on the memory. I could almost feel the circuits firing in my brain. I breathed in. I sniffed again with desperation and abandon.” Fragment by fragment, wisps of scent registered, but faded again. Recognising the citrusy scent of lemon one day, she expanded her smell repertoire to work on nuances, introducing essential oils of lime, grapefruit, sweet orange and tangerine to practice distinguishing the differences. A year on, and she still had not fully recovered, yet, as if in compensation, she became increasingly aware and appreciative of the sensual gifts of touch and texture, music and sound, art and colours, “shaved beets, walnuts and sweet potato: a rainbow of colour and texture I now relished.”
Stephanie became acutely aware of the connection between taste and smell, and the bland void left in their absence. But she describes how this lack was filled as her other senses were stirred. She developed a keener awareness of tones, textures and colours, which seemed sharper and more defined, and her increased appreciation began to exceed compensation.
The qualities of the four essential oils selected to stimulate the sense of smell extend beyond simple scent detection stimulation. Each scent is distinctive, and yet complex, revealing many layers and characteristics (see below), and also express qualities associated with taste. In Ayurveda and elemental modalities, for example, the taste (and qualities) of clove bud is aligned with bitter, 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 (see appendix fig 2). To be clear, I am not recommending the internal ingestion of essential oils here.
Scent description of the four smell test essential oils
Clove: Fresh, fruity top note, sweet, spicy, warm, woody, minty, phenolic, with warm, spicy, woody middle and dry out notes.
Eucalyptus globulus: Powerful, camphoraceous, herbal, medicinal, with a warm, woody-scented undertone, and non-descript dry out notes.
Lemon: Fresh, light, sharp, citrus, zesty, reminiscent of lemon peel, with sweet middle notes and warm, non-descript, dry out notes.
Rose: Otto: Complex, rich, intense, powerful, beeswax-like, highly floral, rosy, with waxy, floral, spicy (clove-like), green, metallic middle notes, then tenacious warm, floral, spicy, dry out notes. Absolute: intense, sweet, floral, rose, waxy, honey, spicy, green, cortex, geranium, metallic, with rich, spicy, sweet, floral middle notes, and warm, floral, honey-like dry out notes. Used extensively in perfumery.
NB: Distilled Rose Otto is an extremely expensive essential oil and is often substituted with less expensive solvent-extracted Rose absolute oil. Both versions are often adulterated, so be sure to purchase these oils from a reputable supplier.
Collectively, these essential oils stimulate the immune system, 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 (see appendix fig. 2).
Essential oils can be used singularly, but can also be blended together (using 2 to 6 complementary oils) to create a particular theme (woody, fruity, floral etc.). A simple blend I find very useful for easing the symptoms of a cold, or ‘flu, or simply to clear my head in the morning or before meditation, consists of eucalyptus globulus, geranium and peppermint (one drop of each on a tissue, or three to four of each in a nasal inhaler). This blend is refreshing, ‘clearing’, anti-viral and anti-microbial and a useful preventative remedy. Applied in a nasal inhaler, kept in a pocket or bag, this blend of essential oils can be discretely retrieved and ‘sniffed’ as and when required.
This article explores the loss of sense of smell caused by viral infection, such as colds, ‘flu, and more recently, COVID-19.
We are surrounded by viruses and other microbes with which we share a symbiotic and, mostly, healthy and supportive relationship. Some microbes are pathogenic, and some become pathogenic if they proliferate without being kept in check. A healthy immune system works in collaboration with viruses and microbes to maintain internal equilibrium and resilience.
COVID-19 is apparently a novel virus with mild to severe symptoms (debate ensues with regard to its source and structure – the virus has not been isolated in the usual way so its specific identity is unclear). One of the less severe, but non-the-less distressing symptoms of this and other SARS-type viruses is loss of the sense of smell. Recent research indicates that essential oils have a significant role to play as aids to recovery of viral initiated loss of sense of smell.
While viral infection may ‘take down’ the ability of olfactory neurons to register scent molecules, some scent molecules can still traverse the epithelium and directly enter the brain. Smelling a scent, while also at the same time accessing memories evoked by that scent, may initiate related feelings and sensations, even imagination, in a way that in turn may begin to re-awaken or stimulate olfactory neural pathways. Essential oil molecules may also aid tissue regeneration and repair.
The four essential oils selected for the ‘smell training’ exercise (clove, eucalyptus globulus, lemon and rose) express a diverse and complex range of scent nuances between them, yet each essential oil exudes its own unique and distinctive odour quality. These scents also express odour qualities that correlate with three of the four basic tastes (sweet, bitter and sour). Forty five per cent of smell training participants regain their sense of smell. (Hopkins 2021, Hummel 2018, 2009) Along with their sensual qualities, these oils are also anti-viral and anti microbial, and may also evoke various psycho-emotional responses that might alleviate other post-viral symptoms of COVID-19, such as fatigue, depression, and lack of concentration, while also staving residual infection and averting further spread.
You will find detailed information about the individual properties and qualities of essential oils, and how to apply them safely and effectively, in my books: Healing with Essential Oils, Essential Oils for the Whole Body, and Essential Oils for Mindfulness and Meditation, published by Healing Arts Press, Inner Traditions USA.
Reference (in order of appearance in text)
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
Rohwer, F., Prangishvili, Lindell, D. (2009) Roles of viruses in the environment. Society for Applied Microbiology. https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1462-2920.2009.02101.x
Virgin, H. (2013) Interactions between the mammalian virome, disease susceptibility genes, and the phenome. NASEM Health and Medicine Division: You Tube Lecture. https://www.youtube.com/watch?v=WImapQyeOG4
Ji, Sayer (2020) Regenerate: unlocking your body’s radical resilience through the new biology, Hay House, London p 52-3
Roossinck, M. J. (2015) Move over bacteria! Viruses make their mark as mutualistic microbial symbionts. Journal of Virology, 2015; JVI.02974-14 DOI: 10.1128/JVI.02974-14 https://jvi.asm.org/content/89/13/6532
Young, R. O. PhD. (2021) Disease, germs, viruses and vaccinations. Interview with Sasha Stone https://sachastone.com/dr-robert-young-speaking-to-sacha-stone (interview removed from you tube) / alternative source re virus information Lies, more lies and damned lies Interview with Sacha Stone, Robert Young and Judy Mikoits https://sachastone.com/stone-mikovits-o-young/
Young, R. O. PhD. (2020) Do Germs Like Corona Virus Cause Disease? https://www.drrobertyoung.com/post/do-germs-like-the-coronavirus-cause-disease
Sousa, A (sourced 2021) Viruses: Genetically encoded messages for communication between individuals. Open Access Text. https://www.oatext.com/viruses-genetically-encoded-alarm-messages-for-communication-between-individuals.php#Article
Bush, Z. (2021) The last 30 years of microbiome research necessitates a radical shift in our model of human health. https://zachbushmd.com/knowledge-virome/
Bush, Z. (2020) Knowledge – The Virome. You Tube Interview. https://www.youtube.com/watch?v=TEb33U0hHxM
Roosinck, M. J. (2015) Plants, viruses and the environment. Virology (Elsevier) vol 479-480 p 271-277. https://www.sciencedirect.com/science/article/pii/S0042682215001816
Schrader, J. (2015) Cytokines and Antibodies. Biomedical Research Centre, University of British Columbia. https://brc.ubc.ca/research/cytokines-and-antibodies-j-schrader/
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/
Vasey, C. (2018) Natural Antibiotics and Antivirals: 18 Infection-Fighting Herbs and Essential Oils: Healing Arts Press, Rochester, Vermont USA
Sander, G., Heckman, M., Weghuber, J. (2020) Immunomodulatory Activities of Selected Essential oils. Biomolecules 10(8): 1139. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464830/
Han, X., Parker, T. L., Dorsett, J. (2017) An essential oil blend significantly modulates immune responses and the cell cycle in human cell cultures. Taylor and Francis on line. https://www.tandfonline.com/doi/full/10.1080/23312025.2017.1340112
Kuriyama, H., Watanabe, S., Nakaya, T., Shigemori, I., Kita, M., Yoshida, N., Masaki, D., Tadai, Toshiaki, Ozasa, K., Fukui, K., Imanishi, J. (2005) Immunological and Psychological Benefits of Aromatherapy Massage. Evidence Based Complementary and Alternative Medicine 2(2): 179-184. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1142199/
Williams, S. C. P. (2014) Human Nose can Detect a Trillion Cells. Brain Behaviour and Biology. Science https://www.sciencemag.org/news/2014/03/human-nose-can-detect-trillion-smells
Godfrey, H. D. (2019) Essential Oils for the Whole Body: The dynamics of topical application: Healing Arts Press, Rochester, Vermont USA
Leffingwell, J. C. (sourced on line 11th February 2021) Olfaction: a review. Leffingwell and Associates. http://www.leffingwell.com/olfaction.htm
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
N, W., Yang, X., Yang, D., Bao, J., Li, R., Xiao, Y., Hou, C., Wang, H., Liu, J., Yang, D., Xu, Y., Cao, Z., Gao, Z. (2020) Role of ngiotensin-converting enzyme 2 (ACE2) in COVID-19. Critical Care no. 442. https://ccforum.biomedcentral.com/articles/10.1186/s13054-020-03120-0
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
Hummel, T., Rissom, K., Redden, J., Hahner, A.,Weidenbecher, M., Huttenbrink, K-B. (2009) Effects of Olfactory Training in Patients with Olfactory Loss. Laryngoscope. https://onlinelibrary.wiley.com/doi/abs/10.1002/lary.20101
Hopkins, C. Prof. (8th January 2021) Hope for recovery for loss of smell for COVID patients. Sky News Interview https://www.facebook.com/watch/?v=857906648400464
Asif, M., Saleem, M., Yarseen, H. S.’ Zarzour, R. A. (2020) COVID-19 and therapy with essential oiks having anti-viral, anti-inflammatory, and immunodulatory properties. Inflammopharmacology 28:1153-1161. file:///Users/Heather/Downloads/Asif2020_Article_COVID-19AndTherapyWithEssentia.pdf
Shi, Y., Wang, Y., Shao, C., Huang J., Gan, J. Huang, X., Bucci, E., Piacentini, M., Ippolito, G., Melino, G. (2020) COVID-19 infection: the perspectives on immune responses. Cell Death and Differentiation 27 1451-1454. https://doi.org/10.1038/s41418-020-0530-3https://www.nature.com/articles/s41418-020-0530-3
Kumar, J. K. S., Vani, M. G., Wang, C-S., Chen, C-C., Chen, Y.C., Lu, L-P., Haung, C-H., Lai, C-S., Wang, S-Y. (2020) Geranium and Lemon Essential Oils and Their Active Compounds Downregulate Angiotensin-Converting Enzyme 2 (ACE2), a SARS-CoV-2 Spike Receptor-Binding Domain, in Epithelial Cells. Plants (Basel) 9(6): 770. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7355681/
Zuo, M (2020) Vitamin C deployed in big doses to help treat coronavirus patients. Southern China Morning Post, China/Society 28th March 2020.https://www.scmp.com/news/china/society/article/3077341/vitamin-c-deployed-big-doses-help-treat-coronavirus-patients
Hemila, H. (2003) Vitamin C and SARS coronavirus; Journal of Antimicrob Chemother, 56:6 p1049-1050. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7110025
Kakodkar, P., Kaka, N., Baig, M. N. (2020) A Comprehensive Literature review on the Clinical Presentation, and Management of the Pandemic Coronovirus Disease 2019 (COVI-19). 12th April, 12(4): e7560. https://www.ncbi.nlm.gov/pmc/articles/PMC7138423
Ayyadurai, S., Dr. MIT PhD (2020) Coronavirus is the right time to discuss immune health: You Tube https://www.youtube.com/watch?v=lzC59WiW_Fs&feature=youtu.be
Cahill, Dolores Prof. (2020) Debunking the Narrative, https://www.bitchute.com/video/WcRzSveTq9eu/
Gao, T., Ding, X., Chai, J., Zhang, Z. (2017) The Influence of Resilience on Mental Health: The Role of General Wellbeing. International Journal of Nursing Practice 23(3)
Conversane, C., Rotondo, A, Lensi, E., Vista, O. D., Arpone, F., Reda, A. M. (2010) Optimism and Its Impact on Mental and Physical Well-Being. Clin. Pract. Epidemiol Ment. Helath 6: 25-29
Feuer, S. (2019) How I Brought My Nose Back to Life. Narratively. Pocket Worthy. https://getpocket.com/explore/item/how-i-brought-my-nose-back-to-life
Brower, V. (2004) When the Immune System goes on the Attack. EMBO Rep. Science and Society 5(8) p757-760. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1299128/
Gibbs, J. E. (2019) Essential Oils, Asthma, Thunderstorms, and plant gases: a prospective study of respiratory responses to ambient biogenic volatile organic compounds. Journal of Asthma Allergy, 12:169-182. https://pubmed.ncbi.nlm.nih.gov/31417289/
Lui, D. T., Besser, G., Lang, M., Sharma, G., Pablik, E., Renner, B., Mueller, C. A. (2020) Odor Mixtures in Identification Testing using Sniffin Sticks: The SSomix Test. Nature Research. https://www.nature.com/articles/s41598-020-65028-7
The Human Microbiome. Center for Ecogenetics and Environmental Health. https://depts.washington.edu/ceeh/downloads/FF_Microbiome.pdf Sourced January 2021
Tisserand, R., Young, R. (2014) Essential Oil Safety: A guide for Health Care Professionals 2nd ed: Churchill Livingstone, Elsevier, Edinburgh
Valnet, Dr. J. (1980) The Practice of Aromatherapy: C.W. Daniel Co. Ltd., Saffron Walden UK
Wang, H., Song., L., Ju, W., Wang, X., Dong, L., Zhang, Y., Ya, P., Yang, C., Li, F. (2017) The acute airway inflammation induced by PM2.5 exposure and the treatment of essential oils in Balb/c mice. Scientific Reports. 7:44256. https://www.ncbi.nlm.gov./pmc/articles/PMC5343586/
Williams, D. G. Williams (2006) The Chemistry of Essential Oils: an introduction for aromatherapists, beauticians, retailers, and students: Micelle Press, Dorset England
Fig 1. Essential Oils that have demonstrated anti-viral and anti-microbial properties
Almeida, L.F., Paula, J.F., Almeida, R.V., Williams, D.W., Hebling, J., Cavalcanti, Y.W.; Efficacy of citronella and cinnamon essential oil on candida albicans biofilms; Acta Odontol Scand 2016 Jul: 74(5): p 393-8; PubMed
Alves-Silva, J.M., Zuzarte, M., Goncalves, M.J., Cavaleiro, C., Cruz, M. T., Cardoso, S.M., Salqueiro, L.; New Claims for Wild Carrot (Daucus carota carota) Essential Oil; Evidence Based Complementary and Alternative Medicine 2016; 2016: 9045196, PubMed
Fisher, K., Phillips, C.A. (2006) The effect of lemon, orange and bergamot essential oils and their components on the survival of Campylobacter jejuni, Escherichia coli O157, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus in vitro and in food systems. Journal of Applied Microbiology 101(6): 1232-40. https://www.ncbi.nlm.nih.gov/pubmed/17105553
Garozzo, A., Timpanaro, R., Bisignano, G., Castro, A. (2009) In vitro antiviral activity of Melaleuca alternifolia essential oil: Society for Applied Microbiology.https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1472-765X.2009.02740.x
Han X, Parker TL (2017) Anti-inflammatory activity of clove (Eugenia caryophyllata) essential oil in human dermal fibroblasts. Pharm Biol. 2017 Dec;55(1):1619-1622.
Kavanaugh, N.L., Riggeck, K., Selected Antimicrobial Essential Oils Eradicate Pseudomonas spp and Staphylococcus aureus Biofilms: Applied and Environmental Microbiology 2012 78(11): p 4057-4061, American Society for Microbiology: ncbi.nim.nih.gov
Marotta, S. M., Giarratana, F., Parco, A., Neri, D., Ziino, G., Giuffrida, A., Panebianco, A. (2016) Evaluation of the Antibacterial Activity of Bergamot Essential Oils on Different Listeria Monocytogenes Strains. Italian Journal of Food Safety 5(4): 6176.
Navarra, M., Mannucci, C., Delbo, M., Calapai, G. (2015) Citrus bergamia essential oil: from basic research to clinical application. Front Pharmacol. 6:36. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4345801/
Nunez, L., Aquino, M.D.; Microbicide activity of clove essential oil (Eugenia caryphylleta); Brazilian Journal of Microbiology 2012 Oct-Dec; 43(4): p 1255-1260
Ooi, L.S., Li, Y., Kam, S.L., Wang, H., Wong, E.Y., Ooi, V.E.; Anti microbial activities of cinnamon oil and cinnamaldehyde from the Chinese medicinal herb Cinnamomum cassie Blume; Am J Chin Med 2006; 34(3): p 511-22. https://libpaper.jnu.edu.cn/papers/browse/browsePaInfo.action;jsessionid=C5143518B4CE3C82D0E099C3A0C653F4?id=2962
Pattnaik S, Subramanyam VR, Kole C (1996) Antibacterial and antifungal activity of ten essential oils in vitro. Microbios. 1996;86(349):237-46. https://www.ncbi.nlm.nih.gov/pubmed/8893526
Perna, S., Spadaccini, D., Botteri, L., Girometta, C., Riva, A., Allegrini, P., Petrangolini, G., Infantino, V., Rondanelli, M. (2019) Efficacy of bergamot: From anti‐inflammatory and anti‐oxidative mechanisms to clinical applications as preventive agent for cardiovascular morbidity, skin diseases, and mood alterations. Food Sci Nutri 7(2): 369-384. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6392855/
Pramod, K., Ansari, S. H., Ali, J. (2010) Eugenol: A Natural Compound with Versatile Pharmacological Actions. Natural Product Communications, vol. 5 no. 12 199 – 2006. https://journals.sagepub.com/doi/pdf/10.1177/1934578X1000501236
Radha G., Chandi, C.R., Dash, S.K., Mishra, R.K.; In vitro antimicrobial potential assessment of carrot and celery seed essential oils against 21 bacteria; Journal of Essential Oil Bearing Plants, 2004, vol 7 issue 1 p 79-86
Seenivasan Prabuseenivasan, Manickkam Jayakumar, Savarimuthu Ignacimuthu (2006) In vitro antibacterial activity of some plant essential oils. BMC Complement Altern Med. 2006; 6: 39. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1693916/
Seyed Fazel Nabavi, Arianna Di Lorenzo, Morteza Izadi, Eduardo Sobarzo-Sánchez, Maria Daglia, Seyed, Mohammad Nabavi (2015) Antibacterial Effects of Cinnamon: From Farm to Food, Cosmetic and Pharmaceutical Industries. Nutrients. 2015 Sept; 7(9): 7729-7748. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4586554/
Sharifi-Rad, J., Sureda, A., Tenore, G.C., Daglia, M., Sharifi-Rad, M., Valussi, M., Tundis, R., Sharifi-Rad, Ma., Koizzo, M.R., Ademiluyi, A.D., Sharifi-Rad, R., Ayatollahi, S.A., Iriti, M.; Biological Activities of Essential Oils: From Plant Chemoecology to Traditional Healing Systems: Molecules 2017 Jan; 22(1): 70 Published online 2017 Jan 1.doi: 10.3390/molecules22010070 PubMed
Swamy, M.K., Akhtar, M.J., Simon, U.R.; Anti Microbial Activity of Six Essential Oils Against Human Pathogens and Their Mode of Action (an updated review); Evidenced Based Complementary and Alternative Medicine 2006; 2016:3012462
Varga A., Acimo, M., Starkouic J., Cvetkovic, M.; Anti microbial properties of essential oils from wild and cultivated carrot seed; (Conference Paper) 2016: Research Gate
Wei, L.S., Wee, W., Chemical composition and anti microbial activity of citronella essential oil against systemic bacteria of aquatic animals; Iran Journal of Microbiology 2013 Jun: 5(2): p 147-152; PubMed PMC 3696851
Further references available on request.
Fig. 1. The Elemental Relationship to Smell and Taste
The main odour and taste qualities: Sweet, Bitter, Sour, Salty, Umami (savory)
Four Essential Oils – associated smell/taste qualities
Pungent (between Sour and Bitter), Bitter
Pungent (between Sour and Bitter)
Sweet, Pungent (between Sour and Bitter), Astringent (between Sour and Bitter
Salty (Mineral), Umani (savoury)
Ayurveda qualities and associated elements
Earth and Water. Increases saliva and mucus secretions
Earth and Fire. Stimulates digestion, assimilation, metabolism and elimination
Water and Fire. Stimulates elimination (digestion) and reduces gases
Fire and Air: Stimulates digestion and circulation, promotes clearance of excess water via sweating, relieves muscle pain, enhances metabolism
Air and Ether. Detoxifies senses, improves taste, restores micro-ecology (kills pathogenic bacteria, fungi, molds and parasites)
Air and Earth. Decongests, drying, cooling
Chinese Elemental qualities associated with taste
Earth. Stomach and digestive system
Fire. Heart and cardiovascular system
Wood. Liver and nervous system
Water. Kidney and nervous system
Fire and Air: Lungs, lymph and immune system
A small particle consisting of either genetic RNA or DNA, enclosed by a protein coat (capsid), which may or may not be surrounded by a lipid membrane envelope, and which may infect all types of organism.
A complete functional virus that has capacity to infect living tissue (an infectious virus), consisting of either genetic RNA or DNA, enclosed with a protein coat (capsid), envelope and membrane proteins that allow the virus to bind to a host cell and enter.
Smaller than a virus, a viroid is a circular single-stranded covalent infectious RNA strand without a protein coat, that replicate by RNA-RNA transcription, and which lack protein coding. Viroids only infect higher plant cells; for example, viroids enter the pollen and ovule and are then transmitted to the developing seed – when the seed germinates the plant becomes infected.
Sub-viral or satellite particle. Possess linear or circular RNA genetic material. They do not replicate autonomously, requiring cells infected with a virus to function as a helper (that is, to provide a protein coat). Virusoids infect plants and are associated with Hepatitis D virus.
A mis-folded protein, which is infectious (pathogenic) in nature, encoded by host chromosomes (found in the nucleus of animal and plant cells). Prion protein triggers normal protein to fold abnormally, which causes disease (for example, transmissible neurodegenerative diseases, such as CJD). Prions cause tissue damage and cell death in surrounding tissues.