Essential oils are the oldest and some of the most powerful therapeutic agents known to man. They have a long history of use in healing and in religious ceremony throughout the ancient world, as well as their use as fragrance. Some, particularly frankincense, are cited repeatedly in many Judeo-Christian and Muslim religious texts. They were used to cure every ailment "from gout to a broken head." Others, such as myrrh, lotus, and sandalwood oils were widely used in ancient Egyptian purification and embalming rituals. Still others, such as clove and lemon, were highly valued as antiseptics hundreds of years before the discovery of modern antiseptics.
Aromatics, as they were called, were some of the most prized treasures of the ancient world - they were traded for gold, silver, and even slaves. To understand how valuable essential oils were in ancient Egypt, records show that when Tutankhamen's tomb was opened in 1922, 350 liters of oil were discovered in alabaster jars. Amazingly, the plant waxes had solidified around the openings of the jars, sealing and preserving the oils! The National Geographic reported in October of 1985 that almost 1,000 years before Christ, dynasties of the ancient world were fighting over the lucrative incense market. Caravans of 3,000 camels transported costly frankincense along the Frankincense Trail, a 2,400-mile-long road that stretched from southern Arabia to the coast of Israel.
It appears that the ancient Egyptians were the first to recognize the therapeutic potential of essential oils. They created fragrances for personal use as well as for ritualistic and ceremonial use in the temples and pyramids. In 1817, the 870 foot long Ebers Papyrus, dating back to 1500 B.C., was discovered. It listed over 800 herbal prescriptions and remedies. Many mixtures were composed of myrrh oil and honey. Myrrh was most often used for embalming, due to its effectiveness in preventing bacterial growth.
- The physicians of Greece came to Egypt to learn about the oils. Even Hippocrates attended the school of Cas.
- The Romans used essential oils by diffusing them in their temples and political buildings. They were fond of soaking in oil-scented baths, then receiving a fragrant oil massage.
- The ancient Arabian people began to study the chemical properties of essential oils. They developed and refined the distillation process.
Europeans began producing essential oils in the 12th century. During the Plague of the Middle Ages, a band of thieves robbed the dead without becoming infected. Finally, four thieves were captured in Marseilles, France, and charged with robbing the dead and dying victims of the plague. At the trial, the magistrate offered them leniency if they would reveal how they managed to avoid contracting the dreaded infection, in spite of their close contact with infected corpses. It was disclosed that these thieves were perfumers and spice traders who had rubbed themselves with a concoction of aromatic herbs (cinnamon, clove, and oregano), which was the source of their immunity. When the great library was burned in Alexandria during the Dark Ages, much of the knowledge of essential oils and their uses was lost. It was only through the cosmetic and perfume industry that some of the valuable science of aromatherapy began to resurface.
Modern Rediscovery of Aromatherapy
The modern rediscovery of the value of essential oils is attributed to French cosmetic chemist, Ren-Maurice Gattefoss, Ph.D. In July of 1910, a lab explosion set him aflame. After extinguishing the flames, he discovered that his hands were quickly developing gas gangrene. But just one rinse with lavender essential oil stopped the horrible process. Healing began the next day.
His discovery was quite accidental - he had plunged his arm into a vessel that he assumed was water. But it actually contained pure lavender oil (Lavendula officinalis). With regular application of lavender oil, the wound healed without a scar. When he investigated the chemistry of the oil, he discovered that some of its chemical components had tremendous healing properties. This incident prompted Dr. Gattefoss to research the healing compounds of essential oils. His research spurred the clinical use of essential oils.
As a result, French physician, Dr. Jean Valnet, used therapeutic-grade essential oils on patients suffering battlefield injuries during World War II. He was able to save the lives of many soldiers who might otherwise have died, even with antibiotics. After the war, he documented his clinical results in his book, The Practice of Aromatherapy. He also shared his knowledge with his student, Daniel Pnol, M.D., who later co-authored the first definitive medical textbook on the chemistry and clinical application of essential oils: L'aromathrapie exactement. Two more of Dr. Valnet's students, Dr. Paul Belaiche and Dr. Jean Claude Lapraz, expanded his work. They clinically investigated the antiviral, antibacterial, antifungal, and antiseptic properties in essential oils.
What Are Essential Oils?
Essential oils are highly concentrated natural plant extracts; a drop or two can produce significant results. An entire plant, when distilled, might produce only a single drop of essential oil. That is why their potency is far greater than dried herbs. Pressing or distillation extracts the subtle, volatile liquids (meaning they evaporate quickly) from plants, shrubs, flowers, trees, roots, bushes, and seeds, that make up essential oils.
Essential oils are the life-blood of the plant, protecting it from bacterial and viral infections, cleansing breaks in its tissue and delivering oxygen and nutrients into the cells. In essence, they act as the immune system of the plant. That is why they are so essential to the plant - without them, plants could not survive.
In the human body, they have a similar action - such as transporting valuable nutrients to the cells; increasing oxygen intake, and digesting toxic waste in the blood. This is because the three primary elements - carbon, hydrogen and oxygen-are common to both human beings and essential oils. This shared chemistry makes essential oils one of the most compatible of all plant substances with human biochemistry. Not only that, but the lipid-soluble structure of essential oils and the fact that they have a protein-like structure similar to human cells and tissues makes them even more compatible with human tissue.
Essential oils are very different from vegetable oils (also called fatty oils), such as corn oil, olive oil, peanut oil, etc. Fatty oils are produced by pressing nuts or seeds. They are quite greasy, are not antimicrobial nor help transport oxygen, and will go rancid over time. Essential oils, however, are not greasy nor do they clog the pores like vegetable oils can.
Essential oils are highly complex substances. They are mosaics of hundreds - even thousands - of different natural chemicals. The average essential oil may contain anywhere from 80 to 400 known chemical constituents. Many oils contain even more, occurring in minute quantities - but all contributing to the oil's therapeutic effects. It requires years of study to understand these constituents, their activity and functions.
Different varieties of the same oil can have widely different therapeutic actions, depending on their chemistry. For example, basil high in linalool or fenchol is primarily used for its antiseptic properties. However, basil high in methyl chavicol is more anti-inflammatory than antiseptic. A third type, basil high in eugenol, has both anti-inflammatory and antiseptic effects.
In addition, essential oils can be processed in different ways, which dramatically effects their chemistry and medicinal action. Oils that have been redistilled two or three times are obviously not as potent as oils that have been distilled only once. Also, oils that are subjected to high heat and pressure in processing have an inferior profile of chemical constituents, since excessive heat and temperature fractures and breaks down many of the delicate aromatic compounds within the oil - compounds that are responsible for much of the therapeutic action of the oil. Of even greater importance is the fact that some oils are thinned or cut (i.e. adulterated) with synthetic chemicals.
The Different Types of Essential Oils
Essential oils are obtained by different methods - distillation being the most familiar. There are four types of essential oils:
1. Absolutes vs. concretes
Absolutes are "essences," rather than "essential" oils. They are generally obtained from the extraction of a concrete with alcohol. A concrete is the solid waxy residue derived from hexane extraction of plant material (usually the flower petals). This method of extraction is used for botanicals where the fragrance and therapeutic parts of the plant can only be unlocked using solvents. These are not to be used internally, as traces of petrochemicals remain in the oil. Jasmine and neroli are examples of absolutes.
Expressed oils are pressed from the rind of fruits (usually citrus). Tangerines, grapefruits, lemons and oranges are produced by this method. Technically speaking, these are not "essential oils" - they are expressed oils, but they are highly regarded for their therapeutic properties, none the less. It is best to use only organically grown crops for this method, since pesticide residues, especially highly toxic, oil-soluble carbamate and chloride-based petrochemicals, can become highly concentrated in the oil.
Solvent extraction involves the use of oil-soluble solvents, such as hexane, dimethylene-chloride, and acetone. There is no guarantee that the finished product will be free of solvent residues. Steam distillation is the oldest and most traditional method of extraction. Plant material is inserted into a cooking chamber, and steam is passed through it. After the steam is collected and condensed, it is processed through a separator to collect the oil. The amount of pressure used, the amount of time the plant material is steamed and the material the steam chamber is constructed of contribute a great deal to the quality of the oil (or lack of).
How Essential Oils Are Used
Historically, there have been three models for using essential oils: the French, the German, and the English methods. The English traditionally dilute a small amount of essential oil in vegetable oil and massage the body to relax and relieve stress. The French prefer to ingest (swallow) therapeutic-grade essential oils. Many French practitioners have found that taking the oils internally is highly effective.
The Germans recommend inhalation of the essential oils. There is good reason for this - research has shown that these aromatic compounds can exert strong effects on the brain, especially on the hypothalamus (the hormone command center of the body) and the limbic system (the seat of emotions). Some essential oils can dramatically increase oxygenation and activity in the brain. Oils also increase ozone and negative ions, which inhibit bacterial growth. Essential oils can make chemicals non-toxic by fracturing their molecular structure. European scientists have found that essential oils work as natural chelators, bonding to metallics and chemicals and carrying them out of the body. Diffused essential oils make outstanding air filtration systems, helping to remove dust particles from the air and destroying odors from mold, cigarettes, animals, etc.
When diffused, the oils reach the brain by means of the olfactory system. The olfactory membranes have about 800 million nerve endings that receive micro-fine, vaporized oil particles. They carry them along the axon of the nerve fibers and connect them with the secondary neurons in the olfactory bulb. The impulses are then transported to the limbic system and the olfactory sensory center at the base of the brain. Then they pass between the pituitary and pineal gland and move to the amygdala - the memory center. The impulses than travel to the gustatory center where the sensation of taste is perceived.
The best method of application depends on the need. In some cases, inhalation might be preferred over topical application if the goal is to induce weight loss or balance mood and emotions. In other cases, topical application would produce better results, as in the case of muscle or spinal injuries. For indigestion, peppermint oil taken orally is very effective. Yet peppermint can also produce the same results when massaged on the stomach. In some cases, all three methods of application (topical, inhalation and ingestion) are interchangeable and may produce similar benefits. The two most common methods of essential oil application are cold-air diffusing and neat (undiluted) topical application. Healing response is greatly enhanced when essential oils are incorporating into the disciplines of reflexology, Vita Flex, acupressure, acupuncture, auricular techniques, lymphatic massage, spinal touch, and the Raindrop Technique.
What Makes Essential Oils Therapeutic-Grade?
Essential oils come from various parts of plants - the seeds, bark, leaves, stems, roots, flowers, and fruit. The oils can be distilled from the plant material or extracted. The majority are distilled. The key to producing a therapeutic-grade essential oil is to preserve as many of the delicate aromatic compounds within the essential oil as possible - elements that are very fragile and destroyed by high temperature and high-pressure. Contact with chemically reactive metals (i.e., copper or aluminum) is another danger to the fragile aromatic compounds in oils. To insure a high grade of essential oil, it is imperative to use stainless steel cooking equipment at low pressure and low temperature for long periods of time.
The purity of an essential oil is also determined by its chemical constituents. There are many variables that can affect these constituents. These can include:
- Soil conditions
- Quality of fertilizer and whether it was organic or chemical
- Harvest season
- Harvest methods
- Distillation process
- The part or parts of the plant used for distillation
One plant can produce several different chemotypes (biochemical variations). The chemotypes vary according to climate, altitude and growing conditions. For example, the later thyme is distilled in the growing season (i.e., late summer or fall), the more thymol the oil will contain. If it is distilled in the early summer, thymol levels will be very low; hence, the oil will be less effective, if at all. A toxic oil is worse than an ineffective oil, however. Essential oils grown with agrochemicals can be dangerous.
Pesticides, herbicides and chemical fertilizers can react with the essential oil during distillation, producing toxic compounds. And synthetic oils not only lack therapeutic benefits, but also carry risks. Natural essential oils contain hundreds of different chemical compounds, many of which have not been identified yet, but which bring important therapeutic properties to the oil. Although chemists have managed to recreate some of the constituents and fragrances of oils, there are many molecules and isomers that are impossible to manufacture in the laboratory. There simply are no substitutes for the purest essential oils.
While there are no regulations in America, a set of standards has been established in Europe that outlines the chemical profile and principal constituents that quality essential oils should have. These standards are known as AFNOR and ISO (Association French Normalization Organization Regulation and International Standards Organization). They are guidelines that help buyers differentiate between a therapeutic-grade essential oil and lower grade oils with similar chemical makeup and fragrance. One well known company with AFNOR certification in America is Young Living Essential Oils, whose oils are constantly being analyzed and graded according to the AFNOR standards.
The AFNOR certification is one of the most reliable indicators of essential oil quality. It is a stringent standard that differentiates true therapeutic-grade essential oils from similar (but inferior) Grade A essential oils. It was developed in France by chemist Hervi Casabianca, Ph.D., who recognized that the constituents within an essential oil had to occur in certain percentages in order for the oil to be considered therapeutic. He and other scientists and doctors combined their research to create the AFNOR standards.
With this indicator, oils can be checked to see if they meet AFNOR standards. If some constituents are too high or too low, the oils cannot be AFNOR or ISO certified. For example, if two or more marker compounds in an essential oil fall below the allowable range, the oil cannot meet the AFNOR standard. It cannot be called therapeutic-grade essential oil, even though it is still Grade A quality.
Without AFNOR standards, it is difficult to tell a therapeutic-grade essential oil from a Grade A essential oil. As an example, Lavender oil is frequently produced from hybrids, yet claimed to be genuine. AFNOR standards help distinguish true lavender from various species of hybrid lavender (actually lavandin). Tasmania produces a lavandin that mimics the chemistry of true lavender. The only way to determine its origin is by analyzing the chemical fingerprint using high-resolution gas chromatography and comparing it with the AFNOR standard for genuine lavender.
Analyzing an essential oil by gas chromatography is complex and highly technical. The injection mixture, film thickness, column diameter and length, and oven temperature must fall within certain parameters. Most labs in the United States use equipment that is only adequate for analyzing synthetic chemicals and marker compounds in vitamins, minerals and herbal extracts, but cannot properly analyze the complexity of natural chemicals found in essential oils.
Two companies we know if that use the proper machinery and test standards for AFNOR essential oils analysis (considered the gold standard) - Flora Research and Young Living Essential Oils. But even gas chromatography (GC) has limitations. It is very difficult to distinguish between natural and synthetic compounds using GC analysis. This is why oils must be analyzed by a technician specially trained in the interpretation of a gas chromatograph chart. He/she can examine the entire chemical fingerprint of the oil, and all the important clues, to determine if the oil is adulterated or pure.
Toxic and Adulterated Oils and Mislabeling
Adulteration of essential oils is becoming more and more common these days. As the demand for them grows, the supply of top-grade essential oils dwindles. The temptation to thin the oils with solvents, then add synthetic fragrance is great. In the last several years, France exported 100 times more lavender oil than it produced. This can only be possible if the oil is being thinned. True lavender oil (Lavandula angustifolia) is expensive and difficult to find.
Most of the lavender oil sold in America today is actually the hybrid, Lavandin, grown and distilled in China, Russia, France and Tasmania. It is shipped to France and cut with synthetic linolyl acetate to improve the fragrance. Then propylene glycol, DEP or DOP (odorless solvents) are added and it is labeled as Lavandula officinalis. Many times it also goes through heat processing to burn off the camphor the hybrid contains and then thinned with more linolyl acetate to appear as lavender. These bottles line the shelves of health food stores, herb shops and department stores, selling for $5.00 to $7.00 per half ounce. Unfortunately, most consumers don't know the difference.
Frankincense is very commonly adulterated. This essential oil requires 12 hours of steam distillation from expensive resin to be therapeutic-grade. Inexpensive frankincense oil that sells for $25 an ounce or less, is invariably distilled with alcohol or other solvents. Lemon oil is another commonly adulterated essential oil. Terpene waste fractions left over from the industrial refining of citrus products and/or synthetic limonene is often purchased from chemical houses and used to dilute or "extend" genuine lemon oil. Since terpenes and limonene naturally occur in lemon oil, even a gas chromatograph cannot distinguish between synthetic and natural limonene.
The most commonly adulterated oils include frankincense, myrrh, lemon, peppermint, cistus, helichrysum, lavender and birch or wintergreen, although all essential oils may be adulterated easily. Most consumers do not know that adulterated oils can cause rashes, burning, and skin irritations. The petrochemical solvents in them can cause intense allergic reactions and toxic accumulations. And that they are devoid of any therapeutic benefits whatsoever. It is very important to know about the integrity of the company from whom you are buying the essential oil. It is also very important for the company or vendor to know about the integrity of the oil. Many vendors do not realize that the essential oils they sell come from chemical laboratories. There are huge chemical companies on the East Coast that specialize in the duplication of essential oils. For every kilo of pure essential oil that is produced, there are between 10 and 100 kilos of synthetic oils created.
In addition, some bottles do not contain the oil stated on the label. Oils marked as "clove" may be distilled from the leaf instead of the bud. Clove leaf oil is less expensive but does not have the same chemistry or therapeutic properties as clove bud oil. Many times, essential oils marked "cinnamon" are actually "cassia." Birch oil is often really Wintergreen - at least in this case, the oils are nearly comparable. But, very often, synthetic methyl salicylate is added to low-grade birch or wintergreen oils to "improve" its quality. As you can see, labeling can be very misleading - considering there is no agency responsible for certifying that an essential oil is therapeutic grade. There is no requirement that ingredients be listed on essential oils bottles. Therefore, unscrupulous manufacturers can literally get away with making any claims they want. Once again, it is up to the consumer to educate himself or herself and know the difference.
The Fragrance Factor
Aromatherapy means to treat with aroma through inhalation (although it also encompasses the topical application of essential oils). Research has shown that we respond to aroma within one to three seconds. Scientists are just beginning to explore how aroma reaches and influences the human brain, emotions and body. An oil's fragrance is created when vapor evaporates from it. The heavier the molecular weight of the oil, the less volatile it is (the less it will evaporate). Oils with lighter molecular weights, evaporate or 'flash off' quickly. Therefore, the scents of lavender or geranium last only about 20 minutes. Heavier oils such as myrrh, frankincense, sandalwood, and patchouli evaporate slower, and therefore, their scent lasts longer.
As the molecules in a fragrance evaporate into the air and are inhaled, olfactory membranes (protected by the mucous lining of the nose) capture them. These membranes are lined with receptor cells that can be considered hair-like extensions of nerve fibers. Each fragrance molecule fits itself into specific receptor cells, like a puzzle piece. The stimulation by odor molecules causes the receptors to trigger electrical impulses to different parts of the brain. These nerve impulses are transmitted to the limbic system of the brain. The brain then sends more impulses to different parts of the body, depending on type and function.
The limbic system is directly connected to the parts of the brain that control heart rate, blood pressure, breathing, memory, stress levels, and hormone balance. Because of this, essential oils can have profound physiological and psychological effects. Have you ever noticed that a scent or fragrance can instantly evoke a memory or an emotion on an unconscious level? This is because the sense of smell is the only one of the five senses that is directly linked to the limbic lobe of the brain - the emotional control center. Emotions such as anxiety, depression, fear, anger, as well as joy all emanate from this region.
The limbic lobe can also directly activate the hypothalamus - the "master gland." The hypothalamus functions as the hormonal control center of the body. It releases chemical messengers that affect the production of growth hormones, sex hormones, thyroid hormones, and neurotransmitters. Essential oils, through their fragrance and molecular structure, can directly stimulate both the limbic lobe and the hypothalamus. In this way, essential oils can exert a profound effect on the body and the mind.
Brief Introduction to Essential Oil Chemistry
Essential oils are made up of many chemical constituents. No two oils are alike in their structure or their effects. Below is a list of some of the main constituents found in essential oils:
Each of these can be broken down into numerous smaller units. Take terpenes, for example. This classification includes monoterpenes, sesquiterpenes, sesquiterpene lactones, Di-terpenes, etc. Listing them all is beyond the scope of this brief overview. Each constituent has its own action, or effects. For example, the ketones found in lavender, hyssop and patchouly, stimulate cell regeneration. Whereas, phenols, found in oregano and thyme oil, are highly antimicrobial.
Because the chemistry of essential oils is very complex, essential oils are diverse in their effects. This also supports their antimicrobial effects, because the wide variety of antiseptic compounds in essential oils makes the mutation of microorganisms extremely difficult. In l985, Dr. Jean C. Lapraz stated that no microbe could survive in the presence of the essential oils of cinnamon or oregano.
Basic Chemical Structure
Essential oils molecules are made up primarily of carbon, hydrogen, and oxygen.
The aromatic constituents of essential oils are built from hydrocarbon chains (carbon and hydrogen atoms). They are normally joined together in ring-like chemical structures. The chains are held together by carbon atoms linked together. Oxygen, hydrogen, nitrogen, sulfur, and other carbon atoms attach at various points of the chain, to make up the different oils. The aromatic-ring structure of essential oils is much more complex than the simpler, linear carbon-hydrogen structure of fatty oils. Essential oils also contain sulfur and nitrogen atoms that fatty oils do not have.
The basic building block of many essential oils is a five-carbon molecule called an isoprene. Most essential oils are built from isoprene. This is the building block that makes up the terpenoids. When two isoprene units link together, they create a monoterpene; when three join, they create a sesquiterpene; and so forth. Triterpenoids are some of the largest molecules found in essential oils. They consist of 30 carbon atoms - or six isoprene units linked together.
Different molecules in the same essential oil can exert different effects. For example, the azulene in German chamomile has powerful anti-inflammatory compounds. The bisobolol German chamomile also contains has sedative and mood-balancing properties. Other compounds in German chamomile perform still different functions, such as speeding the regeneration of tissue.
This is because the chemical structure of an essential oil determines its function. Phenols generally create antibacterial activity. Carvacrols have anti-inflammatory activity and Limonines are antiviral. A single species of plant can have several different chemotypes based on its chemical composition. A plant such as basil grown in one area might produce an essential oil with a completely different chemistry than basil grown in another location.
This discussion is meant as an introduction to a vast field of study that is beyond the scope of this website. For more information, the following publications may be helpful:
- Essential Oil Chemistry by D. Williams.
- Lavandes and Lavandins by Christiane Meunier, Aix-en-Provence 1985.
- Phytochemical Dictionary edited by Jeffrey B. Harborne and Herbert Baxter.
- Journal of Essential Oil Research (JEOR) Tel: (630) 653-2155 Fax: 630 653-2192.
- Aromatherapie by Jean Valnet, M.D., Healing Arts Press, Rochester, VT, 1982.
- Aromatherapy by Ren-Maurice Gattefoss, Ph.D., Girardot, Paris 1937.
- L'aromathrapie exactement by Daniel Pnol, M.D., and Pierre Franchomme.