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Monday, September 13, 2021

Traditional medicine

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Traditional_medicine

Traditional medicine in a market in Antananarivo, Madagascar

Botánicas such as this one in Jamaica Plain, Boston, cater to the Latino community and sell folk medicine alongside statues of saints, candles decorated with prayers, lucky bamboo, and other items.

Traditional medicine (also known as indigenous or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies before the era of modern medicine. The World Health Organization (WHO) defines traditional medicine as "the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness". Traditional medicine is often contrasted with scientific medicine.

In some Asian and African countries, up to 80% of the population relies on traditional medicine for their primary health care needs. When adopted outside its traditional culture, traditional medicine is often considered a form of alternative medicine. Practices known as traditional medicines include traditional European medicine, traditional Chinese medicine, traditional indigenous Mayongia magic and medicine(Assam), traditional indigenous medicine of Assam and rest of NE India, nattuvaidyam (indigenous medicine practised in south India), traditional Korean medicine, traditional African medicine, Ayurveda, Siddha medicine, Unani, ancient Iranian Medicine, Iranian (Persian), Islamic medicine, Muti, and Ifá. Scientific disciplines which study traditional medicine include herbalism, ethnomedicine, ethnobotany, and medical anthropology.

The WHO notes, however, that "inappropriate use of traditional medicines or practices can have negative or dangerous effects" and that "further research is needed to ascertain the efficacy and safety" of such practices and medicinal plants used by traditional medicine systems. As a result, the WHO has implemented a nine-year strategy to "support Member States in developing proactive policies and implementing action plans that will strengthen the role traditional medicine plays in keeping populations healthy."

Usage and history

Classical history

In the written record, the study of herbs dates back 5,000 years to the ancient Sumerians, who described well-established medicinal uses for plants. In Ancient Egyptian medicine, the Ebers papyrus from c. 1552 BC records a list of folk remedies and magical medical practices. The Old Testament also mentions herb use and cultivation in regards to Kashrut.

Many herbs and minerals used in Ayurveda were described by ancient Indian herbalists such as Charaka and Sushruta during the 1st millennium BC. The first Chinese herbal book was the Shennong Bencao Jing, compiled during the Han Dynasty but dating back to a much earlier date, which was later augmented as the Yaoxing Lun (Treatise on the Nature of Medicinal Herbs) during the Tang Dynasty. Early recognised Greek compilers of existing and current herbal knowledge include Pythagoras and his followers, Hippocrates, Aristotle, Theophrastus, Dioscorides and Galen.

Roman sources included Pliny the Elder's Natural History and Celsus's De Medicina. Pedanius Dioscorides drew on and corrected earlier authors for his De Materia Medica, adding much new material; the work was translated into several languages, and Turkish, Arabic and Hebrew names were added to it over the centuries. Latin manuscripts of De Materia Medica were combined with a Latin herbal by Apuleius Platonicus (Herbarium Apuleii Platonici) and were incorporated into the Anglo-Saxon codex Cotton Vitellius C.III. These early Greek and Roman compilations became the backbone of European medical theory and were translated by the Persian Avicenna (Ibn Sīnā, 980–1037), the Persian Rhazes (Rāzi, 865–925) and the Jewish Maimonides.

Some fossils have been used in traditional medicine since antiquity.

Medieval and later

Arabic indigenous medicine developed from the conflict between the magic-based medicine of the Bedouins and the Arabic translations of the Hellenic and Ayurvedic medical traditions. Spanish medicine was influenced by the Arabs from 711 to 1492. Islamic physicians and Muslim botanists such as al-Dinawari and Ibn al-Baitar significantly expanded on the earlier knowledge of materia medica. The most famous Persian medical treatise was Avicenna's The Canon of Medicine, which was an early pharmacopoeia and introduced clinical trials. The Canon was translated into Latin in the 12th century and remained a medical authority in Europe until the 17th century. The Unani system of traditional medicine is also based on the Canon.

Translations of the early Roman-Greek compilations were made into German by Hieronymus Bock whose herbal, published in 1546, was called Kreuter Buch. The book was translated into Dutch as Pemptades by Rembert Dodoens (1517–1585), and from Dutch into English by Carolus Clusius, (1526–1609), published by Henry Lyte in 1578 as A Nievve Herball. This became John Gerard's (1545–1612) Herball or General Historie of Plantes. Each new work was a compilation of existing texts with new additions.

Women's folk knowledge existed in undocumented parallel with these texts. Forty-four drugs, diluents, flavouring agents and emollients mentioned by Dioscorides are still listed in the official pharmacopoeias of Europe. The Puritans took Gerard's work to the United States where it influenced American Indigenous medicine.

Francisco Hernández, physician to Philip II of Spain spent the years 1571–1577 gathering information in Mexico and then wrote Rerum Medicarum Novae Hispaniae Thesaurus, many versions of which have been published including one by Francisco Ximénez. Both Hernandez and Ximenez fitted Aztec ethnomedicinal information into the European concepts of disease such as "warm", "cold", and "moist", but it is not clear that the Aztecs used these categories. Juan de Esteyneffer's Florilegio medicinal de todas las enfermedas compiled European texts and added 35 Mexican plants.

Martín de la Cruz wrote an herbal in Nahuatl which was translated into Latin by Juan Badiano as Libellus de Medicinalibus Indorum Herbis or Codex Barberini, Latin 241 and given to King Carlos V of Spain in 1552. It was apparently written in haste and influenced by the European occupation of the previous 30 years. Fray Bernardino de Sahagún's used ethnographic methods to compile his codices that then became the Historia General de las Cosas de Nueva España, published in 1793. Castore Durante published his Herbario Nuovo in 1585 describing medicinal plants from Europe and the East and West Indies. It was translated into German in 1609 and Italian editions were published for the next century.

Colonial America

In 17th and 18th-century America, traditional folk healers, frequently women, used herbal remedies, cupping and leeching. Native American traditional herbal medicine introduced cures for malaria, dysentery, scurvy, non-venereal syphilis, and goiter problems. Many of these herbal and folk remedies continued on through the 19th and into the 20th century, with some plant medicines forming the basis for modern pharmacology.^[22]

Modern usage

The prevalence of folk medicine in certain areas of the world varies according to cultural norms. Some modern medicine is based on plant phytochemicals that had been used in folk medicine. Researchers state that many of the alternative treatments are "statistically indistinguishable from placebo treatments".

Knowledge transmission and creation

Indigenous medicine is generally transmitted orally through a community, family and individuals until "collected". Within a given culture, elements of indigenous medicine knowledge may be diffusely known by many, or may be gathered and applied by those in a specific role of healer such as a shaman or midwife. Three factors legitimize the role of the healer – their own beliefs, the success of their actions and the beliefs of the community. When the claims of indigenous medicine become rejected by a culture, generally three types of adherents still use it – those born and socialized in it who become permanent believers, temporary believers who turn to it in crisis times, and those who only believe in specific aspects, not in all of it.

Definition and terminology

Traditional medicine may sometimes be considered as distinct from folk medicine, and the considered to include formalized aspects of folk medicine. Under this definition folk medicine are longstanding remedies passed on and practiced by lay people. Folk medicine consists of the healing practices and ideas of body physiology and health preservation known to some in a culture, transmitted informally as general knowledge, and practiced or applied by anyone in the culture having prior experience.

Folk medicine

Curandera performing a limpieza in Cuenca, Ecuador

Many countries have practices described as folk medicine which may coexist with formalized, science-based, and institutionalized systems of medical practice represented by conventional medicine. Examples of folk medicine traditions are traditional Chinese medicine, traditional Korean medicine, Arabic indigenous medicine, Uyghur traditional medicine, Japanese Kampō medicine, traditional Aboriginal bush medicine, Native Hawaiian Lāʻau lapaʻau, and Georgian folk medicine, among others.

Australian bush medicine

Generally, bush medicine used by Aboriginal and Torres Strait Islander people in Australia is made from plant materials, such as bark, leaves and seeds, although animal products may be used as well. A major component of traditional medicine is herbal medicine, which is the use of natural plant substances to treat or prevent illness.

Native American medicine

American Native and Alaska Native medicine are traditional forms of healing that have been around for thousands of years.

Nattuvaidyam

Nattuvaidyam was a set of indigenous medical practices that existed in India before the advent of allopathic or western medicine. These practices had different set of principles and ideas of the body, health and disease. There were overlaps and borrowing of ideas, medicinal compounds used and techniques within these practices. Some of these practices had written texts in vernacular languages like Malayalam, Tamil, Telugu, etc. while others were handed down orally through various mnemonic devices. Ayurveda was one kind of nattuvaidyam practised in south India. The others were kalarichikitsa (related to bone setting and musculature), marmachikitsa (vital spot massaging), ottamoolivaidyam (single dose medicine or single time medication), chintamanivaidyam and so on. When the medical system was revamped in twentieth century India, many of the practices and techniques specific to some of these diverse nattuvaidyam was included in Ayurveda.

Home remedies

A home remedy (sometimes also referred to as a granny cure) is a treatment to cure a disease or ailment that employs certain spices, herbs, vegetables, or other common items. Home remedies may or may not have medicinal properties that treat or cure the disease or ailment in question, as they are typically passed along by laypersons (which has been facilitated in recent years by the Internet). Many are merely used as a result of tradition or habit or because they are effective in inducing the placebo effect.

One of the more popular examples of a home remedy is the use of chicken soup to treat respiratory infections such as a cold or mild flu. Other examples of home remedies include duct tape to help with setting broken bones; and duct tape or superglue to treat plantar warts; and Kogel mogel to treat sore throat. In earlier times, mothers were entrusted with all but serious remedies. Historic cookbooks are frequently full of remedies for dyspepsia, fevers, and female complaints. Components of the aloe vera plant are used to treat skin disorders. Many European liqueurs or digestifs were originally sold as medicinal remedies. In Chinese folk medicine, medicinal congees (long-cooked rice soups with herbs), foods, and soups are part of treatment practices.

Criticism

Safety concerns

Although 130 countries have regulations on folk medicines, there are risks associated with the use of them (i.e. zoonosis, mainly as some traditional medicines still use animal-based substances). It is often assumed that because supposed medicines are natural that they are safe, but numerous precautions are associated with using herbal remedies.

Use of endangered species

Sometimes traditional medicines include parts of endangered species, such as the slow loris in Southeast Asia.

Endangered animals, such as the slow loris, are sometimes killed to make traditional medicines.

Shark fins have also been used in traditional medicine, and although their effectiveness has not been proven, it is hurting shark populations and their ecosystem.

The illegal ivory trade can partially be traced back to buyers of traditional Chinese medicine. Demand for ivory is a huge factor in the poaching of endangered species such as rhinos and elephants.

History

Dioscorides's 1st century De materia medica, seen here in a c. 1334 copy in Arabic, describes some 1000 drug recipes based on over 600 plants.

Prehistoric times

Plants, including many now used as culinary herbs and spices, have been used as medicines, not necessarily effectively, from prehistoric times. Spices have been used partly to counter food spoilage bacteria, especially in hot climates, and especially in meat dishes which spoil more readily. Angiosperms (flowering plants) were the original source of most plant medicines. Human settlements are often surrounded by weeds used as herbal medicines, such as nettle, dandelion and chickweed. Humans were not alone in using herbs as medicines: some animals such as non-human primates, monarch butterflies and sheep ingest medicinal plants when they are ill. Plant samples from prehistoric burial sites are among the lines of evidence that Paleolithic peoples had knowledge of herbal medicine. For instance, a 60 000-year-old Neanderthal burial site, "Shanidar IV", in northern Iraq has yielded large amounts of pollen from eight plant species, seven of which are used now as herbal remedies. A mushroom was found in the personal effects of Ötzi the Iceman, whose body was frozen in the Ötztal Alps for more than 5,000 years. The mushroom was probably used against whipworm.

Ancient times

The Ebers Papyrus (c. 1550 BC) from Ancient Egypt describes the use of hundreds of plant medicines.

In ancient Sumeria, hundreds of medicinal plants including myrrh and opium are listed on clay tablets. The ancient Egyptian Ebers Papyrus lists over 800 plant medicines such as aloe, cannabis, castor bean, garlic, juniper, and mandrake. From ancient times to the present, Ayurvedic medicine as documented in the Atharva Veda, the Rig Veda and the Sushruta Samhita has used hundreds of pharmacologically active herbs and spices such as turmeric, which contains curcumin. The Chinese pharmacopoeia, the Shennong Ben Cao Jing records plant medicines such as chaulmoogra for leprosy, ephedra, and hemp. This was expanded in the Tang Dynasty Yaoxing Lun. In the fourth century BC, Aristotle's pupil Theophrastus wrote the first systematic botany text, Historia plantarum. In around 60 AD, the Greek physician Pedanius Dioscorides, working for the Roman army, documented over 1000 recipes for medicines using over 600 medicinal plants in De materia medica. The book remained the authoritative reference on herbalism for over 1500 years, into the seventeenth century.

Middle Ages

Illustration of a 1632 copy of Avicenna's 1025 The Canon of Medicine, showing a physician talking to a female patient in a garden, while servants prepare medicines.

In the Early Middle Ages, Benedictine monasteries preserved medical knowledge in Europe, translating and copying classical texts and maintaining herb gardens. Hildegard of Bingen wrote Causae et Curae ("Causes and Cures") on medicine. In the Islamic Golden Age, scholars translated many classical Greek texts including Dioscorides into Arabic, adding their own commentaries. Herbalism flourished in the Islamic world, particularly in Baghdad and in Al-Andalus. Among many works on medicinal plants, Abulcasis (936–1013) of Cordoba wrote The Book of Simples, and Ibn al-Baitar (1197–1248) recorded hundreds of medicinal herbs such as Aconitum, nux vomica, and tamarind in his Corpus of Simples. Avicenna included many plants in his 1025 The Canon of Medicine. Abu-Rayhan Biruni, Ibn Zuhr, Peter of Spain, and John of St Amand wrote further pharmacopoeias.

Early Modern

An early illustrated book of medicinal plants, The Grete Herball, 1526

The Early Modern period saw the flourishing of illustrated herbals across Europe, starting with the 1526 Grete Herball. John Gerard wrote his famous The Herball or General History of Plants in 1597, based on Rembert Dodoens, and Nicholas Culpeper published his The English Physician Enlarged. Many new plant medicines arrived in Europe as products of Early Modern exploration and the resulting Columbian Exchange, in which livestock, crops and technologies were transferred between the Old World and the Americas in the 15th and 16th centuries. Medicinal herbs arriving in the Americas included garlic, ginger, and turmeric; coffee, tobacco and coca travelled in the other direction. In Mexico, the sixteenth century Badianus Manuscript described medicinal plants available in Central America.

19th and 20th centuries

The place of plants in medicine was radically altered in the 19th century by the application of chemical analysis. Alkaloids were isolated from a succession of medicinal plants, starting with morphine from the poppy in 1806, and soon followed by ipecacuanha and strychnos in 1817, quinine from the cinchona tree, and then many others. As chemistry progressed, additional classes of pharmacologically active substances were discovered in medicinal plants. Commercial extraction of purified alkaloids including morphine from medicinal plants began at Merck in 1826. Synthesis of a substance first discovered in a medicinal plant began with salicylic acid in 1853. Around the end of the 19th century, the mood of pharmacy turned against medicinal plants, as enzymes often modified the active ingredients when whole plants were dried, and alkaloids and glycosides purified from plant material started to be preferred. Drug discovery from plants continued to be important through the 20th century and into the 21st, with important anti-cancer drugs from yew and Madagascar periwinkle.

Context

Medicinal plants are used with the intention of maintaining health, to be administered for a specific condition, or both, whether in modern medicine or in traditional medicine. The Food and Agriculture Organization estimated in 2002 that over 50,000 medicinal plants are used across the world. The Royal Botanic Gardens, Kew more conservatively estimated in 2016 that 17,810 plant species have a medicinal use, out of some 30,000 plants for which a use of any kind is documented.

In modern medicine, around a quarter of the drugs prescribed to patients are derived from medicinal plants, and they are rigorously tested. In other systems of medicine, medicinal plants may constitute the majority of what are often informal attempted treatments, not tested scientifically. The World Health Organization estimates, without reliable data, that some 80 percent of the world's population depends mainly on traditional medicine (including but not limited to plants); perhaps some two billion people are largely reliant on medicinal plants. The use of plant-based materials including herbal or natural health products with supposed health benefits, is increasing in developed countries. This brings attendant risks of toxicity and other effects on human health, despite the safe image of herbal remedies. Herbal medicines have been in use since long before modern medicine existed; there was and often still is little or no knowledge of the pharmacological basis of their actions, if any, or of their safety. The World Health Organization formulated a policy on traditional medicine in 1991, and since then has published guidelines for them, with a series of monographs on widely used herbal medicines.

Medicinal plants may provide three main kinds of benefit: health benefits to the people who consume them as medicines; financial benefits to people who harvest, process, and distribute them for sale; and society-wide benefits, such as job opportunities, taxation income, and a healthier labour force. However, development of plants or extracts having potential medicinal uses is blunted by weak scientific evidence, poor practices in the process of drug development, and insufficient financing.

Phytochemical basis

All plants produce chemical compounds which give them an evolutionary advantage, such as defending against herbivores or, in the example of salicylic acid, as a hormone in plant defenses. These phytochemicals have potential for use as drugs, and the content and known pharmacological activity of these substances in medicinal plants is the scientific basis for their use in modern medicine, if scientifically confirmed. For instance, daffodils (Narcissus) contain nine groups of alkaloids including galantamine, licensed for use against Alzheimer's disease. The alkaloids are bitter-tasting and toxic, and concentrated in the parts of the plant such as the stem most likely to be eaten by herbivores; they may also protect against parasites.

Modern knowledge of medicinal plants is being systematised in the Medicinal Plant Transcriptomics Database, which by 2011 provided a sequence reference for the transcriptome of some thirty species. The major classes of pharmacologically active phytochemicals are described below, with examples of medicinal plants that contain them.

Alkaloids

Alkaloids are bitter-tasting chemicals, very widespread in nature, and often toxic, found in many medicinal plants. There are several classes with different modes of action as drugs, both recreational and pharmaceutical. Medicines of different classes include atropine, scopolamine, and hyoscyamine (all from nightshade), the traditional medicine berberine (from plants such as Berberis and Mahonia), caffeine (Coffea), cocaine (Coca), ephedrine (Ephedra), morphine (opium poppy), nicotine (tobacco), reserpine (Rauvolfia serpentina), quinidine and quinine (Cinchona), vincamine (Vinca minor), and vincristine (Catharanthus roseus).

The opium poppy Papaver somniferum is the source of the alkaloids morphine and codeine.
The alkaloid nicotine from tobacco binds directly to the body's Nicotinic acetylcholine receptors, accounting for its pharmacological effects.
Deadly nightshade, Atropa belladonna, yields tropane alkaloids including atropine, scopolamine and hyoscyamine.

Glycosides

Anthraquinone glycosides are found in medicinal plants such as rhubarb, cascara, and Alexandrian senna. Plant-based laxatives made from such plants include senna, rhubarb and Aloe.

The cardiac glycosides are powerful drugs from medicinal plants including foxglove and lily of the valley. They include digoxin and digitoxin which support the beating of the heart, and act as diuretics.

Senna alexandrina, containing anthraquinone glycosides, has been used as a laxative for millennia.
The foxglove, Digitalis purpurea, contains digoxin, a cardiac glycoside. The plant was used on heart conditions long before the glycoside was identified.
Digoxin is used to treat atrial fibrillation, atrial flutter and sometimes heart failure.

Polyphenols

Polyphenols of several classes are widespread in plants, having diverse roles in defenses against plant diseases and predators. They include hormone-mimicking phytoestrogens and astringent tannins. Plants containing phytoestrogens have been administered for centuries for gynecological disorders, such as fertility, menstrual, and menopausal problems. Among these plants are Pueraria mirifica, kudzu, angelica, fennel, and anise.

Many polyphenolic extracts, such as from grape seeds, olives or maritime pine bark, are sold as dietary supplements and cosmetics without proof or legal health claims for beneficial health effects. In Ayurveda, the astringent rind of the pomegranate, containing polyphenols called punicalagins, is used as a medicine.

Angelica, containing phytoestrogens, has long been used for gynaecological disorders.
Polyphenols include phytoestrogens (top and middle), mimics of animal estrogen (bottom).

Terpenes

Terpenes and terpenoids of many kinds are found in a variety of medicinal plants, and in resinous plants such as the conifers. They are strongly aromatic and serve to repel herbivores. Their scent makes them useful in essential oils, whether for perfumes such as rose and lavender, or for aromatherapy. Some have medicinal uses: for example, thymol is an antiseptic and was once used as a vermifuge (anti-worm medicine).

The essential oil of common thyme (Thymus vulgaris), contains the monoterpene thymol, an antiseptic and antifungal.
Thymol is one of many terpenes found in plants.

In practice

Licensed commercial cultivation of opium poppies, Tasmania, 2010

Cultivation

Medicinal plants demand intensive management. Different species each require their own distinct conditions of cultivation. The World Health Organization recommends the use of rotation to minimise problems with pests and plant diseases. Cultivation may be traditional or may make use of conservation agriculture practices to maintain organic matter in the soil and to conserve water, for example with no-till farming systems. In many medicinal and aromatic plants, plant characteristics vary widely with soil type and cropping strategy, so care is required to obtain satisfactory yields.

Preparation

A Medieval physician preparing an extract from a medicinal plant, from an Arabic Dioscorides, 1224

Medicinal plants are often tough and fibrous, requiring some form of preparation to make them convenient to administer. According to the Institute for Traditional Medicine, common methods for the preparation of herbal medicines include decoction, powdering, and extraction with alcohol, in each case yielding a mixture of substances. Decoction involves crushing and then boiling the plant material in water to produce a liquid extract that can be taken orally or applied topically. Powdering involves drying the plant material and then crushing it to yield a powder that can be compressed into tablets. Alcohol extraction involves soaking the plant material in cold wine or distilled spirit to form a tincture.

Traditional poultices were made by boiling medicinal plants, wrapping them in a cloth, and applying the resulting parcel externally to the affected part of the body.

When modern medicine has identified a drug in a medicinal plant, commercial quantities of the drug may either be synthesised or extracted from plant material, yielding a pure chemical. Extraction can be practical when the compound in question is complex.

Usage

A herbalist's shop in the souk of Marrakesh, Morocco

Plant medicines are in wide use around the world. In most of the developing world, especially in rural areas, local traditional medicine, including herbalism, is the only source of health care for people, while in the developed world, alternative medicine including use of dietary supplements is marketed aggressively using the claims of traditional medicine. As of 2015, most products made from medicinal plants had not been tested for their safety and efficacy, and products that were marketed in developed economies and provided in the undeveloped world by traditional healers were of uneven quality, sometimes containing dangerous contaminants. Traditional Chinese medicine makes use of a wide variety of plants, among other materials and techniques. Researchers from Kew Gardens found 104 species used for diabetes in Central America, of which seven had been identified in at least three separate studies. The Yanomami of the Brazilian Amazon, assisted by researchers, have described 101 plant species used for traditional medicines.

Drugs derived from plants including opiates, cocaine and cannabis have both medical and recreational uses. Different countries have at various times made use of illegal drugs, partly on the basis of the risks involved in taking psychoactive drugs.

Effectiveness

The bark of the cinchona tree contains the alkaloid quinine, traditionally given for malaria.

Plant medicines have often not been tested systematically, but have come into use informally over the centuries. By 2007, clinical trials had demonstrated potentially useful activity in nearly 16% of herbal medicines; there was limited in vitro or in vivo evidence for roughly half the medicines; there was only phytochemical evidence for around 20%; 0.5% were allergenic or toxic; and some 12% had basically never been studied scientifically. Cancer Research UK caution that there is no reliable evidence for the effectiveness of herbal remedies for cancer.

A 2012 phylogenetic study built a family tree down to genus level using 20,000 species to compare the medicinal plants of three regions, Nepal, New Zealand and the South African Cape. It discovered that the species used traditionally to treat the same types of condition belonged to the same groups of plants in all three regions, giving a "strong phylogenetic signal". Since many plants that yield pharmaceutical drugs belong to just these groups, and the groups were independently used in three different world regions, the results were taken to mean 1) that these plant groups do have potential for medicinal efficacy, 2) that undefined pharmacological activity is associated with use in traditional medicine, and 3) that the use of a phylogenetic groups for medicines in one region may predict their use in the other regions.

Regulation

The practice of Ayurveda in India, such as the running of this Ayurvedic pharmacy in Rishikesh, is regulated by a government department, AYUSH.

The World Health Organization (WHO) has been coordinating a network called the International Regulatory Cooperation for Herbal Medicines to try to improve the quality of medical products made from medicinal plants and the claims made for them. In 2015, only around 20% of countries had well-functioning regulatory agencies, while 30% had none, and around half had limited regulatory capacity. In India, where Ayurveda has been practised for centuries, herbal remedies are the responsibility of a government department, AYUSH, under the Ministry of Health & Family Welfare.

WHO has set out a strategy for traditional medicines with four objectives: to integrate them as policy into national healthcare systems; to provide knowledge and guidance on their safety, efficacy, and quality; to increase their availability and affordability; and to promote their rational, therapeutically sound usage. WHO notes in the strategy that countries are experiencing seven challenges to such implementation, namely in developing and enforcing policy; in integration; in safety and quality, especially in assessment of products and qualification of practitioners; in controlling advertising; in research and development; in education and training; and in the sharing of information.

Drug discovery

The anticancer drug taxol was developed after screening of the Pacific yew, Taxus brevifolia (foliage and fruit shown) in 1971.

The pharmaceutical industry has roots in the apothecary shops of Europe in the 1800s, where pharmacists provided local traditional medicines to customers, which included extracts like morphine, quinine, and strychnine. Therapeutically important drugs like camptothecin (from Camptotheca acuminata, used in traditional Chinese medicine) and taxol (from the Pacific yew, Taxus brevifolia) were derived from medicinal plants. The Vinca alkaloids vincristine and vinblastine, used as anti-cancer drugs, were discovered in the 1950s from the Madagascar periwinkle, Catharanthus roseus.

Hundreds of compounds have been identified using ethnobotany, investigating plants used by indigenous peoples for possible medical applications. Some important phytochemicals, including curcumin, epigallocatechin gallate, genistein and resveratrol are pan-assay interference compounds, meaning that in vitro studies of their activity often provide unreliable data. As a result, phytochemicals have frequently proven unsuitable as lead compounds in drug discovery. In the United States over the period 1999 to 2012, despite several hundred applications for new drug status, only two botanical drug candidates had sufficient evidence of medicinal value to be approved by the Food and Drug Administration.

The pharmaceutical industry has remained interested in mining traditional uses of medicinal plants in its drug discovery efforts. Of the 1073 small-molecule drugs approved in the period 1981 to 2010, over half were either directly derived from or inspired by natural substances. Among cancer treatments, of 185 small-molecule drugs approved in the period from 1981 to 2019, 65% were derived from or inspired by natural substances.

Safety

The Thornapple Datura stramonium has been used for asthma, because it contains the alkaloid atropine, but it is also a powerful and potentially fatal hallucinogen.

Plant medicines can cause adverse effects and even death, whether by side-effects of their active substances, by adulteration or contamination, by overdose, or by inappropriate prescription. Many such effects are known, while others remain to be explored scientifically. There is no reason to presume that because a product comes from nature it must be safe: the existence of powerful natural poisons like atropine and nicotine shows this to be untrue. Further, the high standards applied to conventional medicines do not always apply to plant medicines, and dose can vary widely depending on the growth conditions of plants: older plants may be much more toxic than young ones, for instance.

Pharmacologically active plant extracts can interact with conventional drugs, both because they may provide an increased dose of similar compounds, and because some phytochemicals interfere with the body's systems that metabolise drugs in the liver including the cytochrome P450 system, making the drugs last longer in the body and have a more powerful cumulative effect. Plant medicines can be dangerous during pregnancy. Since plants may contain many different substances, plant extracts may have complex effects on the human body.

Quality, advertising, and labelling

Herbal medicine and dietary supplement products have been criticized as not having sufficient standards or scientific evidence to confirm their contents, safety, and presumed efficacy. A 2013 study found that one-third of herbal products sampled contained no trace of the herb listed on the label, and other products were adulterated with unlisted fillers including potential allergens.

Threats

Where medicinal plants are harvested from the wild rather than cultivated, they are subject to both general and specific threats. General threats include climate change and habitat loss to development and agriculture. A specific threat is over-collection to meet rising demand for medicines. A case in point was the pressure on wild populations of the Pacific yew soon after news of taxol's effectiveness became public. The threat from over-collection could be addressed by cultivation of some medicinal plants, or by a system of certification to make wild harvesting sustainable. A report in 2020 by the Royal Botanic Gardens, Kew identifies 723 medicinal plants as being at risk of extinction, caused partly by over-collection.

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