Use and efficacy of herbal medicines: Part 1 — historical and traditional use
In this first part of a two-part article, the authors examine the role of plants in medicine across time and continents
In this first part of a two-part article, the authors examine the role of plants in medicine across time and continents
Traditional medicine is defined by the World Health Organization as “the sum total of knowledge, skills and practices based on the theories, beliefs and experiences [of] different cultures that are used to maintain health, as well as to prevent, diagnose, improve or treat physical and mental illnesses”.1
It is estimated that 70 to 95 per cent of the populations in developing countries depend on traditional medicine to meet their primary healthcare needs, and most traditional treatments make use of plants and crude extracts.2 In addition to maintaining its popularity in regions of the developing world, adapted versions of traditional medicine are increasing in popularity in industrialised countries. Immigrant populations are also known to use a large number of supplements and medicines derived from their regions of origin.3 Where traditional medicine has been adopted by other countries, outside its native culture, it is usually considered part of complementary and alternative medicine, for example Ayurvedic or traditional Chinese medicine in the UK.1
Plants as therapeutic agents in history
The use of plants as therapeutic agents is culturally ubiquitous, and there is archaeological evidence to suggest that plants have been thus used since prehistoric times. In Europe, the earliest evidence of prehistoric peoples’ use of phytotherapy comes from a mummified body of a man who lived about 5,300 years ago, which was revealed by a retreating glacier in the Tyrol in 1991. Among his personal effects were fruiting bodies of a fungus, birch polypore (Piptoporus betulinus), mounted on a leather thong, which were presumably used to treat abdominal problems caused by an infestation of whipworm (Trichuris trichiura) that he was found to be suffering from.4
Although the archaeological evidence points toward prehistoric phytotherapeutic treatments, any rationale behind their use can only be conjectured, since there can be no certainty in how sickness and disease were perceived or understood. However, ancient Sumerian cuneiform tablets, dating back to 1600 BC, illuminate several centuries of medical knowledge and perceptions from Mesopotamia. Diseases were believed to have been caused by spirits and ghosts, and there were two types of medical practitioner — the ashipu, or sorcerer, who diagnosed ailments by identifying the spirit or sin that had caused illness, and the asu, or specialist in herbal remedies.5,6 A similar split in medical responsibilities is known from many cultures.
From Greek antiquity two large treatises, ‘De Historia Plantarum’ and ‘De Causis Plantarum,’ written by Aristotle’s successor Theophrastus (ca 272–87 BC), included knowledge of medicinal properties of plants.7 Probably the best known of ancient European texts on medicines, however, is ‘De Materia Medica’, compiled by the Greek physician Dioscorides, who practised in Rome at the time of the emperor Nero in around 40–80 AD).
Dioscorides’s book was still being used as a source of pharmacological information until the Renaissance. Roughly 80 per cent of the text is comprised of information about plant medicines, including drawings, habitat, botanical description, drug properties, medicinal uses, side effects, quantities and dosage, harvesting, preparation and storage instructions, adulteration and methods of detection. The format of each chapter is not dissimilar to the monographs of medicinal plants found in pharmacopoeias today.8
Although similarities with modern pharmacopoeias exist, the dominant concepts of disease from ancient Greece and Rome were markedly different from those of today, and based on the humoral theory expounded by Hippocrates (ca 460–370 BC) and later Galen (ca 130–200 AD). In humoral theory it was believed that all diseases stemmed from an imbalance of four main “humours” or fluids (phlegm, blood, “yellow bile” and “black bile”).4 This belief lasted until the 19th century as one of the central tenets of Western medicine.
During the Renaissance, as a result of the advent of the printing press, information on medicinal plants became widely distributed in Europe, with popular herbal textbooks, such as Turner’s (1551) and Gerard’s (1597), changing the role of English apothecaries (antecedents of today’s pharmacists and GPs) and influencing contemporary knowledge of popular medicine.4 The first pharmacopoeias, which were legally binding documents on the composition, preparation and storage of pharmaceuticals, were issued by autonomous cities at the end of the 15th century, with the first in London produced in 1618.4
A study of ancient, medieval and early modern European pharmacopoeias has demonstrated the continuity of materia medica from the fifth to the 19th centuries, showing that the Dioscoridean tradition did not change dramatically during this long period. In contrast, current herbal pharmacopoeias are quite different from those of the 19th century and earlier.9
Another change is the move in western herbal medicine towards a more scientific, evidence-based medicine model (the application of the best available evidence to aid clinical decision making), as opposed to a model based on traditional knowledge (anecdotal knowledge gained from folklore or tradition). The paradigm shift in European herbal medicine towards a rational approach is credited to researcher-physicians of the 18th century, notably William Withering (1741–99), who as a botanist and physician used extensive clinical trials to assess the effects and toxicity of digitalis, the drug produced from the dried leaves of foxglove (Digitalis purpurea L.). A further paradigm shift came with improved analytical techniques in the 19th century, enabling active principle extraction and isolation of specific chemicals from plants, which could then be tested for their pharmacologic and toxicologic effects.4
While Western herbal medicine based on traditional knowledge can be considered a form of traditional medicine, conversely “rational phytotherapy” is the antecedent of today’s conventional medicine, as these isolated chemicals provided the basis for development of modern pharmaceutical drugs, many of which are naturally derived or synthetic analogues of naturally occurring chemical structures.10
Today two systems of Western herbal knowledge — scientific and traditional — remain in operation, and each is widely sought after by patients and consumers. It has been argued that these systems are incompatible, because the latter encompasses non-scientific and esoteric concepts such as “vitalism” (the doctrine that all living things possess a vital or “life” force, distinct from all material, ie, physical or chemical forces).11 Although the theoretical approaches may differ, however, the use of specific substances is common to both, with considerable similarities in what is used for particular treatments.
Traditional medicine today
Societies from both the developed and developing world often have a pluralistic approach to medicine, employing both mainstream medicine and alternative treatments. For example, traditional Chinese medicine is becoming popular in some African countries.12 This “pick and mix” approach is largely dependent on economic factors and availability, as well as socio-culturally based choices. Understanding local traditional medicine concepts often sheds light on why a particular herbal medicine is used. For example, in the favelas of north-east Brazil, toxic plants that induce vomiting and diarrhoea are frequently ingested, because local traditional medicine concepts are still based on humoral theory that promotes the belief that sickness should be “purged” from the body.13 There are plenty of other examples highlighting the diverse philosophical basis for different traditional medicine systems, eg, Ayurveda is based on the concept of balance and harmony of three energetic “forces” (the Tridosha), whereas traditional Chinese medicine has developed from Taoism and the concept of Yin and Yang.4
The adoption of traditional medicines by other cultures poses some challenges, for example, international standards (especially regarding safety and quality) and methods for evaluation may be lacking. There is often limited scientific evidence available on their clinical effectiveness or efficacy, which may be complicated due to the presence of a number of active constituents. These active constituents may result in adverse reactions, or interactions if taken concomitantly with other medicines.14 There are also disparities in regulations at the national level (eg, a single herbal product could be defined either as a food, a dietary supplement or a herbal medicine, depending on jurisdiction). The expanding herbal product market is also leading to unsustainable practices that threaten plant species, potentially leading to extinction in some cases.15
In the UK, the Traditional Herbal Medicines Registration Scheme (THMRS) requires evidence of safety and quality, and at least 30 years of traditional use, including 15 years within the EU, in order for a herbal medicinal product to be registered and legally sold over-the-counter.14
To date, no Ayurvedic or traditional Chinese medicine products have been registered under the THMRS. However, their popularity in the UK means that it is quite likely that a significant number of patients may be using either OTC or prescribed medicines obtained from pharmacies concomitantly with Ayurvedic or Chinese medicines. Due to risks from using unlicensed herbal medicinal products as a result of unregulated safety and quality, in addition to the risk of drug-herb interactions, it is important that pharmacists are aware if patients are using these products.
In summary, the long history of use of herbal medicine products cross-culturally demonstrates their importance to consumers. Pharmacists — especially within community and hospital pharmacies — need to recognise and accept the wide use of these products. Acceptance brings along with it crucial responsibilities to the profession, to ensure that patients are using these products safely, and not to the detriment of their health.
Acknowledgements The background research and SE’s and IR’s positions are supported by a charitable donation to the Centre for Pharmacognosy and Phytotherapy, UCL School of Pharmacy, from Schwabe Pharmaceuticals and Fa Bionorica under the UK government’s matched funding scheme. The donors had no input into writing this article.
1 World Health Organization (WHO) Traditional Medicine. Fact Sheet No. 134; 2008. Available at: www.who.int/mediacentre/factsheets/fs134/en/ (accessed 15 November 2011).
2 Robinson MM, Zhang X. The World Medicines Situation 2011. Traditional Medicines: Global Situation, Issues and Challenges. World Health Organization, Geneva; 2011.
3 Sandhu DS, Heinrich M. The use of health foods, spices and other botanicals in the Sikh community in London. Phytotherapy Research 2006;19:633–42.
4 Heinrich M, Barnes J, Gibbons S, Williamson E. Fundamentals of Pharmacognosy and Phytotherapy. 2nd Edition. Churchill Livingstone, London (in press); 2012.
5 Coleman M, Scurlock J. Viral haemorrhagic fevers in ancient Mesopotamia. Tropical Medicine and International Health 1997;2:603–6.
6 Mohit A. Mental health and psychiatry in the Middle East: historical development. Eastern Mediterranean Health Journal 2001;7:336–47.
7 Theophrastus/Hort AF (translator), Enquiry into Plants, II, Books 6-9. New York: Harvard University Press; 1916.
8 Riddle JM. Dioscorides on Pharmacy and Medicine. University of Texas Press; 1986.
9 De Vos P. European materia medica in historical texts: longevity of a tradition and implications for future use. Journal of Ethnopharmacology 2010;132:28–47.
10 Newman DJ, Cragg GM. Natural products as sources of new drugs over the last 25 years. Journal of Natural Products 2007;70:461–70.
11 Evans S. Changing the knowledge base in Western herbal medicine. Social Science and Medicine 2008;67:2098–106.
12 Hsu E. Chinese medicine in East Africa and its effectiveness. IIAS Newsletter 45:22;2007. Available at: www.iias.asia/files/IIAS_NL45_22 (accessed 9 January 2012).
13 Edwards SE. Medicinal plant sociocultural concepts and terms in NE Brazil. MSc dissertation (unpublished); UCL Medical Anthropology; 1998.
14 Rocha I, Edwards SE, Lawrence MJ et al. Quality and safety of herbal medicinal products: Part 1 — new legislation and production. Pharmaceutical Journal 2012;288:685–6.
15 Hawkins B. Plants for life: Medicinal plant conservation and botanic gardens. Botanic Gardens Conservation International, Richmond, UK; 2008.
About the authors
Sarah Edwards is research fellow, Inês Da-Costa-Rocha is research fellow and Michael Heinrich is head and professor at the Centre for Pharmacognosy and Phytotherapy, UCL School of Pharmacy, London.
M. Jayne Lawrence is chief science adviser and Colin Cable is pharmaceutical sciences information adviser at the Royal Electronicjuice
Correspondence to: Professor Heinrich (email [email protected])
Citation: Electronicjuice URI: 11104718
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