Essential oils are the aromatic, or volatile constituents found in plants. They are basically distillations of the most active physiological properties of the plant. Some in the field of natural wellness explain that essential oils contain the life force of the plants. Indeed, the very name essential oil is derived from the word ‘quintessence’, which means “fifth essential component” – according to Ayurvedic, Chinese, and Aristotelian models of life.

Way before modern physiology was enshrined in medical textbooks, the model for human physiology embraced the five elements; earth, air, fire, water, and the fifth element for living things… spirit.
So, it is said that essential oils are the very ‘spirit’ or ‘essence’ of the plant.
Chemically, essential oils are made up of alcohols, aldehydes, ketones, phenols, terpenes, sesquiterpenes, ethers and esters. All of these chemical names refer to the molecular structure of the oils. And, to a large degree, their functions in the body.

Alcohols, terpenes, and Aldehydes, for example possess astringent properties which help to cleanse and dry. This is why these substances when inhaled, can perform these functions in support of wellness. When eucalyptus, tea tree, camphor and others are diffused into the air, they help to ‘dry’ up mucous secretions, clearing the breathing pathways and an enhancing the ability to recover from a cold or flu.

Many other essential oils exist which are beneficial to wellness. And, more are being discovered every year. And, the pathways they enhance are becoming clearer with the incredible explosion of essential oil users worldwide and, the results that are almost universally reported by them.

Their are several pathways through which essential oils may react with the body and its metabolism. But, the one thing they all have in common is that they all use the blood as a transport medium…except one.

The most important and direct pathway, in terms of its profound and immediate effect on the body, is through the sense of smell. When we inhale essential oils, the vapor first, stimulates small hair-like extensions of our olfactory nerve. This primary effect is emotional as well as physiological. Certain essential oils have effects on blood pressure, heart rate, cognitive abilities, and much more – when simply inhaled.


The olfactory nerve is the only nerve in the human body that directly connects the external environment… to the brain. There is no distinction between the olfactory nerve and the brain centers (archipallium and neopallium) that process the signals for us.

Our other senses (touch, hearing, sight, and taste) involve several nerves, ganglia, and synaptic junctions before the signals reach the brain. This is a form of modulation, or control mechanism which can filter out unwanted or unneeded signals before we are aware of them. Not so for the sense of smell. Signals are unmodulated, unfiltered and uncensored. What you smell is what you get.

The olfactory pathway also stimulates that most primitive part of the brain called the limbic system, which is adjacent to the amygdala. (often referred to, collectively, and imprecisely, as the ‘Reptilian’ brain) This area is important in the processing of the reaction to emotions, desires, appetites and memories. It is also the reason why the sense of smell is directly hard-wired into these areas – for survival reactions.

The second pathway for essential oils is through penetration through the epithelial tissues. Epithelium includes the skin, nasal passages, bronchioles, and alveoli in the lungs. Essential oils can have a strong effect on these primary contact tissues and their underlying tissues. (Astringent properties to clean and clear the skin, as well as antiseptic properties are key properties of many oils commonly used on the skin.)

Once absorbed through the skin’s surface, essential oils quickly penetrate into the interstitial space where their transit into lymphatic and blood vessels is mediated by various physical means such as diffusion, imbibation, etc.

As the oils enter the general circulation, they are made available to every organ and cell of the body. This application of essential oils to the skin and mucosal tissues is considered a large part of the Ayurvedic tradition, and was advanced in the west by Great Britain, which brought the tradition back to Europe during the colonial occupation of India.

As the oil circulates with the blood and lymph, various tissues and organs may ‘choose’ any portion of the essential oil necessary and beneficial for its metabolic process. Also, a curious, passive effect has been observed, where the tissues simply ‘react’ to the presence of the substances without consuming them. A calming or mediating effect akin to sedation – or other beneficial stimulation can be attributed to the oil as it simply passes through.

The practice of ingesting essential oils for wellness purposes is commonly credited to the Franco-European civilization. Yet, again, we learn that in Ayurvedic practice, it has been around for MANY milennia before Paris was even a village.

This third pathway involves the digestive and excretory processes of the body. Some components of essential oils are picked up by the surface of the lungs and by-products/metabolites are out gassed (excreted) as a vapor. For example; Eucalyptol (an alcohol in eucalyptus oil) is transported to the lungs surfaces by the blood stream and calms the mucous membranes as it exits.

Others, such as terpenes in juniper berry oil, are filtered out by the kidneys, and have stimulating effects on the renal tissue, ureters, bladder and urethra as they exit.  Some components of essential oils are absorbed by the liver where they may be held briefly in the gall bladder – and subsequently expressed into the digestive tract, having profound affects on these organ systems as they pass through.

Another example; Rose oil can stimulate bile production as it is processed by the liver. Some constituents tend to migrate toward the skin, where they will exit via the sebaceous glands and become part of the protective acid mantle. Components of yarrow can increase perspiration as they are excreted.

These pathways are the primary explanation(s) as to why essential oils can have such a profound and immediate effects on very deep aspects of human physiology. Ayurvedic research and thousands of years of experience, indicate that very small quantities of oils, almost approaching homeopathic dilutions have the ability to create these effects – and more.
Larger doses do not increase the response appreciably. Therefore, we are reminded, when using essential oils, that; a little really DOES go a long way.

Live Well… Be Well