Chances are you’ve used essential oils most of your life. These substances find their way into many common products, including mouthwashes, perfumes, soaps, household cleaners, and liniments.
You may also find these fragrant oils in their pure form in small, dark bottles lining your health-food store’s shelves. Many people use them as perfume, to scent massage oils, or for aromatherapy. And as the research continues on the chemicals found in plants, several essential oils have emerged as useful medicines.
If you have ever used an essential oil, you may have been surprised by its consistency. Cooking oils are exactly that—oily. But most essential oils have a consistency more like water. The main difference between cooking oils and essential oils is how quickly they evaporate. Although both come from plant sources, this simple contrast makes a world of difference in how they are used.
The word essential refers to plant essences, volatile oils that provide a plant’s flavor and smell. Volatile means that these oils turn from a liquid to a gas (evaporate) very easily at room temperature or higher—this is how they travel to your nose. The “oily” oils, such as corn or peanut oil, are called fixed oils, which means they don’t evaporate, even at the relatively high temperatures necessary for cooking.
Essential oils begin as tiny droplets contained in different plant parts such as leaves, stems, bark, flowers, roots, and fruits. Plants make these oils to protect themselves from insects or other invaders, or to attract pollinators like bees and butterflies. Different oils can come from different parts of the same plant. For example, a single bitter orange tree (Citrus aurantium) provides three different oils: neroli oil from the blossom, oil of bergamot from the fruit peel, and petitgrain from leaves and twigs. Some plants contain very few essential oils.
Essential oils are extracted using one of five methods: steam distillation, enfleurage, maceration, expression, or solvent extraction. Each of these processes breaks down a plant’s cells to release its oils.
Essential oils are highly concentrated: One acre of peppermint may produce a ton of dried leaves but only twelve pounds of essential oil, according to Herbs for Health adviser Steven Foster. Sometimes these oils can be 75 to 100 times more concentrated than the fresh herb, making them very potent.
Essential oils are used in a variety of ways. In cooking, the flavors and aromas from spices and herbs come from their essential oils. The familiar paint thinner turpentine is an essential oil extracted from the southern pine (Pinus palustris), a tree in the pine family. Aromatherapy practitioners use essential oils for emotional and physical well-being. Often, herbs’ medicinal qualities can be traced to compounds in the oils.
In general, essential oils are complex mixtures, containing compounds such as terpenoids, aldehydes, ketones, and phenols, many of which have medicinal properties. Because of their molecular structure, oils can penetrate the skin and enter the bloodstream within twenty to seventy minutes after application.
Most essential oils are for external use only and, even then, some are known skin irritants. Some are toxic when taken internally, even in small amounts. Be sure to use tiny amounts (you may wish to dilute a few drops in a carrier oil such as castor oil) and follow any label instructions carefully.
Some oils are phototoxic (make the skin susceptible to damage by sunlight) or neurotoxic (toxic to the nervous system), while others have abortifacient effects, meaning they may cause miscarriages. Oils to be avoided during pregnancy include basil, cinnamon, citronella, clary sage, clove, cypress, hyssop, juniper, marjoram, rosemary, sage, and thyme. If you have high blood pressure, asthma, or epilepsy, or if you are pregnant, breast feeding, or are thinking of using an essential oil to treat a child, consult a qualified health practitioner.
Once you’re sure that an oil is safe for use, it’s also a good idea to perform an allergy test. Soak a cotton ball in the oil and dab it on the inside of your forearm. Wait a few hours; if any redness or irritation develops, avoid using that particular oil. If you’re allergic to a specific plant—for instance, mint—then it’s likely you will react to the entire family of plants, in this case, wintergreen and other menthols. Given these cautions, start slowly and with proper medical advice.
Below are definitions of words occurring in articles in this issue of Herbs for Health.
Refer to this glossary if you come across words you’re not familiar with as you read.
Alzheimer’s disease: a degenerative condition of the central nervous system that results in premature, gradual, progressive loss of intellectual abilities and changes in personality. Generally found in people over age fifty. Also called dementia.
androgen: hormones responsible for male characteristics.
antioxidant: a compound that prevents cell damage caused by free radicals or oxidation
allopathic: a system of medicine that treats an illness by producing a condition incompatible with or antagonistic to the condition to be cured; for example, taking antibiotics for an infection. Most conventional Western medicinal practices follow this theory.
apoptosis: the protective process by which a cell self-destructs if severe DNA damage occurs, such as damage that might result in a cancerous growth
benign prostatic hyperplasia, or BPH: noncancerous abnormal growth rate of normal prostate cells. Prostate overgrowth pinches the urethra, and men develop a variety of urinary problems.
bitter: a blend of bitter and often aromatic plants whose tastes stimulate production of digestive juices
chronic fatigue syndrome: a controversial diagnosis for symptoms including profound lethargy not helped by sleep; memory problems; depression; and severe exhaustion from simple activities. Many different causes have been suggested, including allergies, drug reactions, and chronic infection with the Epstein-Barr virus.
coenzyme: coenzymes enable enzymes to convert food into water and energy
electrolytes: substances such as potassium, chloride, and sodium, which help the body regulate electrical currents and the flow of water molecules across cell membranes
enteric-coated: coated to allow the medicine to pass through the stomach acids unaltered and to disintegrate in the intestines
estrogen: the generic term for a class of female sex hormones, including estradiol, estrone, and estriol
estrogen replacement therapy (ERT): an oral synthetic estrogen replacement that mimics hormones in the body
hormone replacement therapy (HRT): a combination of synthetic estrogen and progesterone taken to increase hormone levels that decrease during menopause
Parkinson’s disease: a chronic progressive nervous disease usually occurring later in life. It is linked to decreased production of a neurotransmitter in the brain called dopamine. Symptoms include muscular tremors, weakness, and a shuffling gait.
phytochemistry: the chemistry of plants and plant functions
phytoestrogens: estrogen-like compounds found in plants
tinnitus: chronic ringing in the ears
tonic: a substance that invigorates or strengthens the system by acting as a stimulant or by gradually restoring health
spastic colon, or irritable bowel syndrome: a condition in which the normal rhythmic contractions of the colon become spasms causing intermittent abdominal pain (aching, cramping, burning, or sharp pains) with constipation, diarrhea, or both.
Cooksley, Valerie. Aromatherapy: A Lifetime Guide to Healing with Essential Oils. New Jersey: Prentice Hall, 1996.
Foster, Steven. Herbs for Your Health. Loveland, Colorado: Interweave Press, 1996.
Pengelly, Andrew. Constituents of Medicinal Plants. Muswellbrook, New South Wales: Sunflower Herbals, 1996.
Robbers, James E., M. K. Speedie, and V. E. Tyler. Pharmacognosy and Pharmabiotechnology. Baltimore: Williams & Wilkins, 1996.
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