Botanical medicine is a vital component of the healing arts that draws on the accumulated and developing knowledge of the medicinal properties of plants in the prevention and treatment of disease. Botanical medicine includes medical herbalism, a healing art that relies on the synergistic and curative properties of plants to treat symptoms and disease and maintain health, and pharmocognosy, the study of natural products. Botanical medicine is an important component of numerous traditional medical systems and therapies, including traditional Chinese medicine (TCM), Ayurvedic medicine , naturopathy, indigenous and shamanic medicine, homeopathy , flower essence therapy, and aromatherapy . Botanical medicine has survived for many thousands of years in some form and in all cultures throughout the world. The study of the plant lore of these various cultures is known as ethnobotany.
Plants have been used since prehistoric times as medicinal remedies applied in various ways to provide relief from irritations as minor as a mosquito bite to situations as catastrophic as the plague. In modern medicine, some drugs are derived from plants, and many of these medicines are used in ways that are similar to their traditional uses. Many more drugs in modern medicine, however, are synthetic, and part of the reason for this trend is economic: plants can rarely be patented, so a pharmaceutical company will not gain the exclusive right to sell a plant-derived medication even after expensive research and marketing. Also, the processing of plants into a medicine cannot be as easily standardized and controlled as the manufacturing of a synthetic. As a result, the efficacy and safety of only a relative few of the traditionally used botanical remedies have been verified by clinical research. Approximately only 5,000 of the estimated 500,000 known species (including subspecies) of plants have been identified and studied for their medicinal properties.
The knowledge of the healing properties of herbs has been preserved from the time of the clay tablets of the ancient Sumerians over 5,000 years ago, to the sacred texts and pharmacopoeias of the Hindu and Chinese cultures, to the works of Greek and Roman physicians preserved by Byzantine scholars, to the European folk herbalists and physicians such as Nicholas Culpeper and, more recently, to the Native American herbalists. One of the earliest records of botanical medicine is the Pen T'Shao Kang Mu, a work attributed to China's Yellow Emperor around 2500 b.c. Another is the Ebers papyrus, an Egyptian medical text dating from 1,550 b.c. The Rigveda, an ancient Hindu scripture, lists more than 1,000 medicinal plants used in the ancient Ayurveda system of medicine, already well developed by 1000 b.c. Theophrastus, who lived from 327–285 b.c. is considered the first scientific botanist; he recorded the use of more than 500 medicinal plants. The Greek physician Dioscorides produced what has been called the first true herbal text, or herbal, the De materia medica in the first century a.d. By the Middle Ages, the monks in medieval European monasteries were working to preserve this ancient knowledge by copying texts and cultivating extensive gardens of medicinal plants. European folk medicine was passed from generation to generation through oral tradition, and later, with the introduction of the printing press, the information became more widely available in popular written texts. Colonists brought their herbal knowledge and plant specimens to settlements in North America and learned from the indigenous Americans how to make use of numerous additional plants native to the New World. The first record of Native American herb use is the manuscript of the Native Mexican physician Juan Badianus in 1552.
The use of herbs for medicinal purposes has been developed over the centuries by personal experimentation, local custom, anecdote, and folk tradition. According to the World Health Organization, an estimated 80% of the global population continues to rely on medicinal plant preparations to meet primary health care needs. For example, a 2003 study found that traditional Arabic herbal medicine is still practiced in the Middle East. The specific chemical constituents of herbs and their unique medicinal action is the subject of ongoing scientific experimentation.
Botanical medicines, when administered properly and in designated therapeutic dosages, can be effective, trigger fewer side effects for most patients than pharmaceutical drugs, and are generally less costly than prescription pharmaceutical drugs.
The benefits of botanical medicine may be subtle or dramatic, depending on the remedy used and the illness being addressed. Herbal remedies usually have a much slower effect than pharmaceutical drugs. Some herbal remedies have a cumulative effect and work slowly over time to restore balance, others are indicated for short-term treatment of acute symptoms. Botanical medicine may be especially beneficial when administered to help with chronic ongoing symptoms.
Traditional Chinese medicine (TCM): This system of healing employs ancient techniques, developed over many thousands of years. For example, among TCM's techniques are acupuncture, moxibustion , and herbal formulas to restore health. Moxibustion is a process that combines acupuncture with the traditional application of the herb mugwort , Artemisia vulgaris, known as Ai ye or Hao-shu. This is a method of heating specific acupuncture points on the body to treat physical conditions, particularly chronic pain . When burnt, the mugwort produces a mild heat able to penetrate deeply into the muscle. TCM also employs specific herbal formulas to restore health and maintain a dynamic balance between two distinct forces known as yin and yang, particularly with regard to the qi. Qi is the vital energy flowing along the meridians or energy pathways of the body. The TCM practitioner is a skilled observer, who relies on diagnostic techniques, including measuring pulse rate from several positions, and noting the general appearance of the patient, such as complexion, eyes, nails, hair, tongue, and posture. The assessment not only includes consideration of the patient's symptomatic complaints, but of numerous personal characteristics including family history, lifestyle, emotional health, environment, diet, and exercise . The medicinal herbs prescribed are usually prepared as a formula based on the unique needs of each patient.
Ayurvedic medicine: This system of healing, literally meaning the science of life or longevity, has been practiced in India for more than 5,000 years. Ayurvedic medicine is concerned equally with the body, mind, and spirit of the person and combines natural therapies to restore balance and harmony. Ayurvedic physicians, like the practitioners of traditional Chinese medicine, use educated observation in diagnosis. In Ayurvedic medicine, there are three basic doshas, or metabolic body types. The success of Ayurvedic treatment depends on the proper diagnosis of imbalances in these characteristic aspects. Ayurvedic medicine emphasizes self-care strategies such as a healthy diet, yoga, meditation , breathing, and exercises to restore the innate harmony of the body. Taste is an important indicator of the medicinal properties of an herb. Plants are categorized according to six plant essences: sweet, sour, salty, pungent, bitter, and astringent. An understanding of how these plant essences act in the body is a necessary component in Ayurvedic medicine for prescribing herbal remedies.
Indigenous and shamanic medicine: These rely on extensive folk knowledge of botanical and animal medicine combined with ceremonial ritual in the treatment of disease. The particular form of indigenous medicine is unique to each tribe. The specific herbal remedies are primarily passed on through oral tradition.
Naturopathy: Naturopathic medicine was established in the eighteenth and nineteenth centuries. The naturopathic doctor, or naturopath, uses gentle methods to boost the body's healing, including nutritional supplements, herbal remedies, proper diet, and exercise to restore health. The doctor works with the patient to educate him or her on ways to restore and maintain a healthy balance in the internal environment that will prevent further illness. Licensed naturopathic doctors pass rational exams that include basic clinical botanical medicine competency, as well as homeopathy.
Homeopathy: Homeopathy was founded in the late eighteenth century by the German physician Samuel Hahnemann . Homeopathy embraces the philosophy of "like cures like." Homeopathy uses extremely dilute solutions of herbs, animal products, and chemicals that are believed to hold a "trace memory" or energetic imprint of the substance used. Sold as over-the-counter medicine, homeopathic remedies are exempt from government regulations applied to pharmaceuticals. Homeopathic remedies may be sold without proof of safety and efficacy as long as they are labeled with the directions for use and the level of dilution.
Flower essences: The use of flower essences attempts to address a more subtle energy beyond the physical symptoms, to treat the emotional and mental roots of disease. The English physician Edward Bach developed a method of extracting what he considered the essence of flowers with the ability to address a broad range of psychological conditions of the human spirit. This system became known as Bach flower remedies . This botanical therapy attempts to match the energetic essence of particular flowers with the same energy in the higher self of an individual, thus strengthening the higher energies and promoting self-realization and restoring health. Bach's theory was that the source of all illness could be found in the conflict between the demands of one's higher self, striving to realize its full potential, and the individual personality or ego with its limiting beliefs and actions that obstruct and block this self-realization. The remedies are believed to have a subtle, soul-healing effect based on an instinctual soul rapport with the particular herb.
Aromatherapy: Aromatherapy uses the essential oil of various herbs extracted by steam distillation or cold pressing of flower, leaf, stem, or root to treat various physical and emotional problems. Herbs have long been valued for their healing fragrance. In 1564 an alchemist named Giovanni Battista della Porta wrote about methods used to separate essential oils from the aromatic distilled waters that had been used in previous centuries. Modern-day aromatherapy was developed by the French chemist Réné-Maurice Gattefosse, in 1937. Aromatherapy identifies the distinct healing properties of various pure essential oils. The small size of the molecules in essential oils enables the chemicals to penetrate bodily tissue easily and to act rapidly on the limbic system which is believed to be the seat of emotions.
The quality of any herbal remedy and the chemical constituents found in the herb depends greatly on the conditions of weather and the soil where the herb was grown, the timing and care in harvesting, and the manner of preparation and storage. Herbs are prepared in a variety of ways depending on the part of the plant that is medicinally active and the results sought. The list of kinds of herbal preparations is long and varied. Some of these preparations include:
- Infusion. Infusion is appropriate for extracting medicinal properties of the leaf, flower, and stem of the plant. Either fresh or dried herb may be used. A standard infusion combines 1 tsp of dried herb, or 2 tsp of chopped fresh herb, per cup of water. Fresh, nonchlorinated water is brought to the boiling point in a non-metallic pot, and the herbs are added. A cover prevents the escape of volatile oils. The tea is infused for 10 to 15 minutes, strained, and can be consumed warm or cold. The prepared tea will keep up to two days in the refrigerator.
- Decoction. Decoction is the best method to extract the mineral salts and other healing components from the coarser herb materials, such as the root, bark, seeds, and stem of the plant. One ounce of the dried plant materials, or 2 oz of fresh plant parts, is added to 1 pt of pure, unchlorinated water in a non-metallic pot. The mixture is brought to a boil, and then the heat is lowered, so the mixture can simmer for about 30 minutes. After straining and covering, a decoction may be refrigerated for up to two days and retain its healing qualities.
- Tincture. Tincture is a method to prepare a concentrated form of the fresh herbal remedy for therapeutic use. These solutions, properly prepared and stored, will retain medicinal potency for many years. To prepare a tincture, a clean glass container is packed with chopped fresh or dried herb, and enough good quality brandy or vodka to cover is poured over the herb. The alcohol/water ratio varies, dependent on the plant and the intended extract. The concentration (depending on the herb) is 25-90%; often the ratio of alcohol to water is about 50/50. The container then needs to be sealed with an airtight lid. The mixture needs to be left in a darkened place to steep for two weeks, and shaken daily. After straining the mixture through a cheesecloth or muslin bag and pouring it into a dark bottle for storage, it is ready for use. Dosage depends on the herb and its designated use. A standard dosage is 2–4 ml of the tincture three times a day. Other fluid extracts may be prepared with glycerine or vinegar.
- Capsule. A capsule is a convenient form for ingesting dried, powdered herbs, usually contained in a gelatin capsule. Gelatin capsules are available in the standard size 00 which holds 200–250 mg of powdered herb. Prepared capsules should be stored in dark glass containers.
- Oil infusion. With this method, the chopped fresh or dried herb is placed in a glass storage container. Enough cold-pressed vegetable oil, such as sunflower or olive oil, is poured into the jar to cover the herb completely. This mixture is sealed and placed on a sunny windowsill for two or three weeks. The infused oil is strained into another jar of the chopped fresh or dried herb. This mixture steeps on a sunny windowsill for another two weeks. After being strained through cheesecloth, this infused oil can be stored in a cool, dark location.
- Ointments. These are prepared with powdered or freshly chopped plant parts combined with melted petroleum jelly or beeswax and vegetable oil. The mixture is simmered in a double boiler for about two hours. The mixture is strained through cheesecloth and poured into small glass storage containers. Ointments provide a spreadable consistency and protective layer for topical application of medicinal herbs to the skin.
- Poultice. A poultice is a hot mixture of the chopped fresh or dry herb that has been boiled briefly, and cooled to a tolerable temperature before application to the affected area. A small amount of oil should be applied to the skin prior to placing the poultice to prevent the herb from sticking. The poultice can be covered with a gauze strip to hold it in place. The poultice can be refreshed every two or three hours as needed.
- Essential oils. This is the highly concentrated extract of an herb obtained through steam distillation or cold compress methods. Essential oils should be diluted in water or in a nontoxic carrier oil before application to the skin to prevent contact dermatitis or sensitization. Essential oils are used for topical application, in bath water, and in aromatherapy. The toxicity of the concentrated essential oil varies depending on the chemical constituents of the herb.
The above list is by no means exhaustive. There are many other botanical medicine preparations available.
Herbal remedies prepared by infusion, decoction, or alcohol tincture from the appropriate plant part, such as the leaf, root, or flower are generally safe when ingested in properly designated therapeutic dosages. However, many herbs have specific contraindications for use when certain medical conditions are present and by pregnant or lactating women. Some herbs are toxic, even deadly, in large amounts, and there is little research on the chronic toxicity that may result from prolonged use. Herbal remedies are sold in the United States as dietary supplements and are not regulated by the Food and Drug Administration (FDA) for content or efficacy. Self-diagnosis and treatment with botanical medicinals may be risky. A consultation with a certified clinical herbalist or naturopathic physician is prudent before undertaking a course of treatment. A 2002 report said that patients often fail to inform their physicians about herbal products they are using, and that patients don't think of them as medicines. Yet many botanical remedies can interact with allopathic medicines and either cancel their effects or cause adverse effects. For example, garlic , ginseng, ginkgo, feverfew, licorice , and other common remedies have anticoagulant properties that can put patients as risk of bleeding during surgery.
Advances in communication technology have made warnings about herbal remedies more important than ever. The Internet includes many sites with unregulated and often unhealthful advice about use of herbal remedies. Many herbalists and allopathic physicians urge patients to use caution when seeking information on herbal treatments on the Internet. One cancer-related study found that only 36% of the web sites found in a search offered information that complied with regulatory guidelines regarding unsubstantiated claims about treatment or cure of disease.
Essential oils should not be taken internally without expert guidance due to the potential for toxicity even in very small amounts. They are not to be used in any form by pregnant or lactating women without competent medical consultation. Essential oil extracts do not contain the full range of phytochemicals present in the whole plant.
Homeopathic remedies are safe because of their extremely dilute nature. These remedies must not be relied upon for treatment of any serious illness or injury. If symptoms persist, other qualified medical help should be sought.
Herbs contain numerous phytochemicals formed in the metabolic process of the plant. These chemicals act on the body in different ways; some of these act on the whole body, while some act on a specific organ or system. An herb's effect may be due to a particular chemical in the herb, or it may be due to an interaction among constituents within the plant. Interactions with other herbs, or with pharmacological drugs, is a matter of concern and a growing area of research.
The pure essential oils of aromatic plants, extracted by steam distillation or cold pressing techniques have been used for more than a century in medicines, food, drink, perfumes, detergents, soaps, cosmetics, in various industrial applications, and in aromatherapy. Some compounds found in plant oils can cause sensitization even in very small amounts. Side effects from external application of some essential oils may include mild skin irritation, such as itching and burning; sensitization, which may lead to recurrent mild to severe adverse reactions such as burning and rash each time the essential oil is used; and phototoxicity, a situation in which certain essential oils react with ultraviolet light and cause reactions from mild skin blotching to severe burning any time the skin is exposed to sunlight.
Research & general acceptance
Botanical treatments are generally accepted as part of mainstream medical treatment around the world except in the United States, where herbal remedies are sold as dietary supplements. As of 2003, the branch of the FDA that regulates botanical products under the rubric of dietary supplements is the Center for Food Safety and Applied Nutrition (CFSAN). Under the Dietary Supplement Health and Education Act of 1994 (DSHEA), the manufacturer of a botanical preparation is responsible for ensuring that it is safe before marketing it; the FDA is responsible for taking legal action if the product proves to be unsafe after it is marketed. The other government agency that has some oversight over botanical preparations in the United States is the National Center for Complementary and Alternative Medicine (NCCAM) of the National Institutes of Health, established by an act of Congress in 1998. NCCAM also supports research into botanical products, herbalism, and other alternative therapies that make use of plant-derived products.
In Germany, an expert committee known as the Commission E was established by the government in 1978 to evaluate the safety and efficacy of the 300 herbs and herb combinations sold in that country. No equivalent regulatory commission exists in the United States.
Determining the safety or toxicity of essential oils has primarily been accomplished through animal testing. Human trials of essential oils using volunteers have also been conducted. Some regulation of and guidelines for the use of essential oils, particularly in food, is accomplished by the World Health Organization (WHO), the Council of Europe, and the U.S. Food and Drug Administration (FDA). Two sources of information on the safety of essential oils used in aromatherapy are the Research Institute for Fragrance Materials, and the International Fragrance Research Association. These organizations conduct ongoing research evaluations of essential oils and publish the findings in the journal, Food and Chemicals Toxicity.
Homeopathic remedies have been tested clinically and, in 1997, an international team of researchers reviewed more than one hundred controlled studies and concluded that the collective results of 26 of these controlled studies indicate that homeopathic remedies produce a somewhat greater benefit than a placebo in the treatment of illness.
Training & certification
Naturopathic physicians are licensed as primary care physicians in many states and complete a four-year graduate level course at a naturopathic medical school. Naturopaths are trained in nutritional medicine, homeopathic medicine, botanical medicine, hydrotherapy , psychology, and counseling.
Traditional Chinese medicine practitioners are heir to the benefits of thousands of years of tradition. This ancient system of health care is experiencing a revival in China after efforts by Chinese Nationalists in the 1930s to eliminate traditional Chinese medical practices in favor of Western medical methods. The ancient way persisted, and traditional Chinese medicine is taught in Chinese medical schools using the traditional medical literature. By the 1990s, China had opened its hospitals to American students of acupuncture and Chinese herbology.
Western herbalism is taught in numerous schools of herbal medicine in the United States, as well as through correspondence and on-line courses. Certification as a clinical herbalist is not required in the U.S. and herbal remedies are widely available commercially as food supplements without a medical prescription.
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Teresa G. Odle
Rebecca J. Frey, PhD
BOTANICALS. Botanicals are fresh or dried plants, plant parts, or plants' isolated or collective chemical components, extracted in water, ethanol, or other organic solvents, plus essential oils, oleoresins, and other extractives used for flavoring, fragrance, functional health benefits, medicine, or other biological and technical activities. Many botanicals, broadly speaking, also can be classified as herbs, plants used for flavor, fragrance, or medicinal qualities, such as caraway, parsley, rosemary, sage, and thyme. Other botanicals fall under the classification of spices, piquant aromatic plant materials, usually of tropical origin, used to season food. Examples include cloves, cinnamon, nutmeg, and pepper. Botanicals commonly are used in foods, drugs, and cosmetics. The cosmetic industry uses over 360 botanical ingredients, classified as "biological additives," to enhance the fragrance, performance, or consumer appeal of products. Botanicals, either in crude form (whole dried plants or plant parts) or in their isolated or modified chemical constituents, also are used in prescription and nonprescription (over-thecounter) drugs. In addition, over 1,600 botanicals and their derivatives are sold in the United States in a special food category called "dietary supplements." In commercial trade, botanicals, though not defined as such, generally refer to dried materials of plant origin sold in bulk form as whole, cut-and-sifted, or powdered ingredients.
Botanicals in Human Experience
Botanists conservatively estimate that 250,000 species of flowering plants exist on Earth. At least 85,000 plant species worldwide have been documented as being used as medicinal botanicals, at least in folk medicine. The World Health Organization estimates that as much as three-quarters of the world's population relies on traditional forms of medicine, chiefly herbal or botanical medicine. Botanicals used in foods, drugs, and cosmetics are an integral part of daily life.
The human experience in the use of botanicals is inextricably interwoven with human history. The first known historical evidence for the use of plants comes from the Middle Paleolithic burial site in Iraq known as Shanidar IV, a Neanderthal grave containing remains of yarrow flowers (Achillea spp.), marshmallow (Althaea spp.), and ephedra (Ephedra spp.), all of which are botanicals still in use in the twenty-first century.
The Ebers papyrus, dating to 1500 b.c.e., was discovered in 1876. This ancient Egyptian manuscript mentions 876 medicines, most of which are of botanical origins. Undoubtedly, ancient Greek scholars learned from their Egyptian predecessors about the use of botanicals in medicine. The writings of Hippocrates (466–377 b.c.e.) refer to many botanical substances. The starting point for Western medicine, and in particular botanical ingredients used in the West in the nineteenth and twentieth centuries, is the first-century work De Materia Medica of Dioscorides of Anazarba in Cilicia. For more than fifteen centuries, all Western cultures depended on this source for information on botanicals. It includes over six hundred botanicals, most of which are in use in the twenty-first century.
Botanicals as Food Additives
Over 250 botanical substances are added during food product manufacturing for flavor, fragrance, or technical characteristics, such as coloring, thickening, or preservative activity. These botanicals are used commonly and extensively, often in the form of concentrated extracts at parts per million levels, as natural ingredient additives for many categories of food products, including baked goods, canned goods, meat products, dairy products, nonalcoholic beverages, and alcoholic beverages. Many botanical ingredients have a long history of use and generally are recognized as safe. However, for a new ingredient, not previously marketed materially in the United States, to enter the American market, it must receive prior approval by the Food and Drug Administration (FDA). The manufacturer (or industry trade organization) may submit toxicological data to the FDA in support of the ingredient's safety.
Botanicals as Dietary Supplements
In 1994 the U.S. Congress passed the Dietary Supplement Health and Education Act, which created a special food regulatory category for dietary supplements, including vitamins, minerals, herbs or other botanicals, amino acids, or other dietary substances used to supplement the diet by increasing the total dietary intake. Concentrates, metabolites, constituents, extracts, or their combinations also are included in the definition. Dietary supplements are regulated as foods rather than as drugs despite the fact that most such products are intended to provide a health benefit. The vast majority of botanicals available on the American market, from over 1,600 plant species, are sold as dietary supplements.
Many well-known botanicals sold as dietary supplements in the United States also are available in other Western countries, notably Germany, where they are regulated as drugs under a special category called phytomedicines. By definition, phytomedicines include the totality of chemical constituents within a botanical or plant part rather than a single isolated chemical component. Well-known botanicals in this category are garlic (Allium sativum), ginkgo leaf extracts (Ginkgo biloba), echinacea (Echinacea purpurea, E. angustifolia, and E. pallida), ginseng (Panax ginseng), kava kava (Piper methysticum), saw palmetto (Serenoa repens), St. John's wort (Hypericum perforatum), and valerian (Valeriana officinalis). In the European markets for these botanicals, quality is strictly regulated. In the United States, it is not; therefore dietary supplements are perceived as "unregulated."
Botanicals in Modern Medicine
Prescription and nonprescription drugs of botanical origin are used widely in modern medicine, primarily as purified derivatives or partially modified secondary chemical compounds. Remarkably it is estimated that approximately 25 percent of drugs in the average American pharmacy are botanical derivatives. Of 121 prescription drugs in use in the early twenty-first century that originate from 90 plant species, 74 percent were discovered in scientific follow-up of historical or folkloric claims of medicinal value. Botanical derivatives used in chemotherapy include paclitaxel (taxol), extracted from yew species (Taxus spp.), used for certain forms of breast and ovarian cancer; vincristine and vinblastine, purified alkaloids extracted from the Madagascar periwinkle (Catharanthus roseus), used in the treatment of leukemias and Hodgkin's disease; and semisynthetic compounds from mayapple (Podophyllum spp.), used in the treatment of testicular and small-cell lung cancers. Nonprescription botanical ingredients include the laxatives psyllium seed (Plantago spp.) and senna leaves (Senna spp.). Some botanicals are the source of both drugs and foods. Morphine, codeine, and other chemical analogs from the opium poppy (Papaver somniferum L.) are used for the management of pain. The opium poppy is also the source of poppy seeds, used as a decorative and flavoring component in the culinary arts.
Foxglove: From Folk Medicine to Modern Botanical
The cardiac glycosides digoxin and digitoxin, extracted from several species of foxglove (Digitalis spp.), are used in the treatment of heart diseases, such as atrial fibrillation and congestive heart failure. This botanical was not well known to the ancients as a medicinal plant. Instead, it was considered a poisonous plant. A British physician, William Withering, introduced the drug to medicine in 1785 in An Account of the Foxglove and Some of Its Medical Uses: With Practical Remarks on Dropsy and Other Diseases, published in Birmingham, England, where Withering served as a physician at the general hospital. In 1775 Withering became aware of the secret family recipe of an elderly patient, Mrs. Hutton, in Shropshire, England. She had developed a reputation for curing "dropsy" (congestive heart failure) when physicians had failed. Withering discovered that the active ingredient was foxglove. Crude extracts of the botanical were prescribed widely in the 1800s, although exact dosing requirements sometimes resulted in fatal overdoses. The crude drug and its preparations have a narrow therapeutic ratio. A small increase in dose, only slightly above that necessary for therapeutic results, can produce toxicity. The discovery and isolation in the leaves of the glycosides responsible for the botanical's pharmacological cardiac effects led to more exact controlled dosage forms with lower risks of toxic effects.
"The Dose Makes the Poison"
Foxglove and its isolated chemicals are a good example of a fundamental principle in the response of a cell, organ, or organism to a botanical drug or food ingredient. The response or expected activity is proportional to the dose. Therefore, research on the effects of a substance on an organism requires measurement of a dose-response relationship. Such information is gathered by measuring responses to appropriately variable amounts of the active agent (usually in laboratory animals). Doses are increased incrementally until 80 percent of the maximal response is achieved. Above the level of 80 percent, usually only small changes in activity are observed. Higher doses also may result in toxic effects. Quantitative analyses of the dose-response curve measure the relative potencies of a drug or extract and help determine at what levels a beneficial or a toxic reaction may occur.
Inhibition or potentiation of a response often involves attachment of a molecule to a cellular receptor site. Targeting cell receptor sites helps direct research to specific activities, such as anti-inflammatory or analgesic (pain-relieving) effects, or to diseases, such as diabetes mellitus or cancer. Mechanisms of action of potential interest often relate to cell receptor site competition. Sometimes effects are mechanical. For example, psyllium seed works as a bulk laxative by absorbing moisture in the intestines, thus increasing bulk and stimulating mechanical peristalsis.
A common adage in toxicology is "the dose makes the poison." In pharmacology, the measure of a substance's margin of safety is known as the "therapeutic index." This index is expressed as the ratio of the dose causing harmful effects to the dose causing a therapeutic effect in a specific proportion of individuals. The amount of a substance that causes death in 50 percent of laboratory animals is expressed as LD50 (dose lethal to 50 percent).
Botanicals Withdrawn Due to Safety Concerns
Most botanicals have a long history of apparent safe use. Ingredients may be withdrawn when new information raises safety concerns. Sassafras (Sassafras albidum) is an example. Sassafras derives its flavor and fragrances from an essential oil comprised of up to 80 percent safrole. In the late 1950s safrole, then used as a primary root beer flavoring, was banned as a food additive due to concerns over serious liver toxicity and carcinogenicity. The ban was subsequently extended to dried sassafras bark sold for the intended purpose of making an herbal tea. Dried sassafras leaves (used as a base for gumbo filé) must also be free of safrole. Another example of a botanical no longer considered safe is comfrey (Symphytum spp.). Popular in the 1970s and 1980s, comfrey leaves and roots were regarded as a virtual cure-all, earning it the name "all-heal." Apparently used safely for centuries, comfrey was found to contain significant amounts of a class of pyrrolizidine alkaloids that cause a condition known as veno-occlusive disease of the liver (resulting in the occluding or clogging of the major veins in the liver). The rare disease can only be diagnosed with a liver biopsy; thus it went unrecognized for decades. Internal use of comfrey products is restricted or prohibited in many countries.
See also Additives; Flowers; Herbs and Spices; Hippocrates; Processing of Food.
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Steven D. Foster