Traditional systems of herbal medicine

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Chapter 12 Traditional systems of herbal medicine

Introduction

All modern medicine is derived originally from ancient herbal traditions. These have evolved to produce the conventional medicine known in the West, which uses both synthetic drugs and isolated natural compounds. Plant extracts are now rarely used by physicians or in hospitals, although herbal remedies are popular with the public and improvements in their formulation have resulted in a new generation of phytomedicines that are more potent than before and also chemically standardized. There is, however, a resurgence of interest in the older Oriental systems; this is due partly to dissatisfaction with conventional treatments and partly to the constantly growing interest in all things natural, environmentally friendly and biodegradable. These older types of medicine are philosophically based, and are holistic in that they treat the patient as a whole rather than as the ‘owner’ of a disease or malfunctioning organ. They also have much in common with traditional medical herbalism as it was, and still is, practised in Europe and America. Whether or not pharmacists, doctors and other healthcare professionals accept the validity of these older medical systems, it is necessary for them to know about their basic principles for two main reasons. First, to be in a position to advise patients who may wish to consult an alternative practitioner and, second, because traditional use is a common starting point in the ongoing search for new drugs.

It is necessary to consider the cultural environment in which traditional remedies are being used to make our expectations more reasonable, put these treatments in the context of Western thinking and widen the criteria of selection of remedies for our own use within modern medicine.

Three types of traditional medicine have been chosen as an illustration:

Traditional medicine can be defined as: Medical practice that includes diagnosis, prevention and treatment, relying on practical experience and observations handed down from generation to generation, whether verbally or in writing.

• Traditional Chinese Medicine (TCM)

• Ayurveda

• Traditional African medicine (TAM) or traditional African medical systems (TAMS).

TAM is an example of a mainly oral tradition, which applies to many types of indigenous medicine. TCM and Ayurveda are popular and highly sophisticated and have evolved through the ages whilst keeping their philosophy intact. All three systems use herbs as well as other forms of treatment. Discussion here, however, will be restricted to herbs since they have pharmacological activities and are, therefore, within the remit of this book. Before doing so, it would be useful to identify some aspects of the general approach of traditional medical systems to health, disease and treatment that affect our perception of them.

In the context of the systems discussed in this chapter, diseases can be considered as minor or self-limiting disorders, or chronic or serious disorders.

Minor or self-limiting disorder

Such ailments include aches and pains, diarrhoea, wounds or injuries for which a common remedy will be usually offered; in addition the facilitation of childbirth will also be considered. The remedy would usually be an indigenous plant or herb, or something that is obtainable from a local market, and would be well known within the community.

Chronic or serious disorders

These may be fatal, life-threatening or debilitating conditions, or those that cannot be diagnosed by indigenous healers; they are often considered to have a ‘supernatural’ component. Examples include forms of cancer, and some genetic or metabolic diseases where obvious lesions may not be seen. Plant remedies will certainly be used, but they may be used as part of a ritual, and treatment will often also involve practices such as divination to find out which gods or ancestors have been offended and what sacrifices may be necessary to appease the supernatural entity. Naturally, the rationale behind the first type of common usage is more logical to Western thought, and scientists would therefore look, for example, for antipyretic or analgesic compounds in a herb known as a cure for fever, or for haemostatic substances in a plant used to staunch bleeding. It may even be possible to speculate, with some knowledge of chemotaxonomy, on the types of compounds that are present (e.g. tannins in a haemostatic plant, salicylates or sesquiterpene lactones in an antipyretic plant). However, if ritual is more often involved in the use of a particular plant, it is almost impossible to surmise what compounds may be present; this approach is therefore much less useful. The plant may be a treasure trove of useful compounds, but the traditional use will not provide any information about it.

The dose

In traditional medicine, this usually means a lack of specific dose. Typically, a calabash, seashell or a tumbler of a decoction may be taken from time to time. Traditional medicine is more concerned with how to take the remedy rather than how much. This aspect of traditional medicine is very important indeed because it means that highly potent plants are rarely part of a traditional pharmacopoeia – pure compounds, accurate balances and volume measurements are not part of such cultures – and some plants which we now find useful were considered dangerous. For example, the foxglove, a source of the cardiac glycoside digoxin, has no historical documentation as a herbal medicine, and it was not until the 1800s that Withering used it for cardiac dropsy (congestive heart failure). Due to the narrow therapeutic index of the drug, it was necessary to develop a standardized preparation, which was powdered leaf, assayed biologically, and compressed into a tablet, before the drug gained widespread acceptance.

Correlation of traditional use with scientific evidence

There may be a correlation between traditional usage and pharmacological action, such as the isolation of antipyretic principles from a ‘fever’ remedy, but, even so, it may turn out different to our expectations. A classic example is ‘fever bark’ (Cinchona), which was traditionally used in South America for fever, but in many tropical countries ‘fever’ really means ‘malaria’. Quinine is actually antipyretic to some extent, but it has a much more relevant property, which is to kill the malaria parasite Plasmodium. Therefore, extracts of plants based on traditional usage should not only be tested for the activity expected, but be put through a battery of tests, since some important modern drugs have been developed from plants used for a different purpose entirely. For example:

• in the Caribbean the periwinkle Catharanthus (Vinca) rosea was used traditionally for treating diabetes, but on further investigation it yielded the powerful anticancer alkaloids vincristine and vinblastine

• Fagara xanthoxyloides, which is used in Nigeria as a chewing stick for cleaning the teeth, has been found not only to be antimicrobial, but also to have antisickling activity, and this finding has sparked off further work into this painful and chronic genetic condition.

Despite the reservations mentioned, traditional medicines have yielded many useful modern drugs, although not as many as poisonous species. Although toxic plants are only occasionally used as medicines, they are well known to the healers and may also be used for nefarious purposes, witchcraft or as ‘ordeal’ poisons, as, for example, Calabar bean (Physostigma venenosum), which is the source of the anticholinesterase physostigmine (eserine).

Asian and oriental medicine

The more systematic forms of traditional medicine arose in the East, particularly in India and China, and from there spread to other parts of the world where they influenced Greek, Arab and other highly sophisticated cultures. Ayurveda originated in India, and TCM in China, but in both cases they have evolved as they were incorporated into local customs; for example, Jamu arose in Indonesia and Kampo in Japan. These medical systems were (and still are) complicated and structured, and had a philosophical and religious aspect far removed from the primitive magic, superstition, divination and sacrifice that are characteristic of African, South American, Pre-Islamic Arabian and other cultures where medical knowledge was an oral (rather than written) tradition. Tibb-I-Islam is Islamic medicine and, therefore, practised by Muslims throughout Asia and the rest of the world, but it is more of a cultural way of looking at health (as dictated by the Koran) than a type of medicine, although of equal impact.

Traditional chinese medicine

The study of TCM is a mixture of myth and fact, stretching back well over 5000 years. At the time, none of the knowledge was written down, apart from primitive inscriptions of prayers for the sick on pieces of tortoise carapace and animal bones, so a mixture of superstition, symbolism and fact was passed down by word of mouth for centuries. TCM still contains very many remedies, which were selected by their symbolic significance rather than proven effects; however, this does not necessarily mean that they are all ‘quack’ remedies! There may even be some value in medicines such as tiger bone, bear gall, turtle shell, dried centipede, bat dung and so on. The herbs, however, are well researched and are becoming increasingly popular as people become disillusioned with Western medicine. Again, Chinese medicine is philosophically based, and as an holistic therapy the concept of balance and harmony is supremely important. The relevant records and documents were discussed earlier (Chapter 2), but additional historical milestones will be included here to show the evolution of TCM into what it is today.

The development of TCM

Shen Nong, the legendary Chinese Emperor, is credited with the discovery of herbal medicine in around 2800 BCE, and he is also reputed to have defined the opposing yet complementary principles eventually known as yin and yang. Confucius (551–479 BC) is celebrated as China’s greatest sage. He established a code of rules and ethics based on the premise that there is an order and harmony of the Universe resulting from a delicate balance of yin and yang forces. Humans should cultivate the five virtues of benevolence, justice, propriety, wisdom and sincerity, in order to exert their own life force in this cycle. Lao Zi extended the Confucian doctrine and taught that man can only achieve personal harmony by bowing to the inevitable. His followers invented a spiritual destination to the mythical ‘Island of the Eastern Sea’ where a herb with the power to bestow immortality was thought to grow. The way (or path) within this natural order of things is called the Tao and the religion is now called Taoism. Along this path, the two basic expressions of yin (negative and passive) and yang (positive and active) are interlocked. This philosophy was refined and extended by Dong Zhongshu to include the inner reaches of man himself, i.e. man as the universe on a small scale, containing within himself the locked cycle of yin and yang. It, therefore, follows that Taoist principles apply to the well-being of man, and extend to diet and medicine as factors in ensuring a balance between physical and mental health.

Food and medicine became inter-related. Herbal medicine was initially the domain of shamans and mountain recluses, who believed that the mountain mists contained high concentrations of qi, the vital essence of life. They practised the ‘way of long life’, which involved a herbal diet and medicine combined with martial arts – a link that continues today. The principles of TCM became consolidated and a search for the ‘elixir of life’ began to obsess the Chinese aristocracy. In TCM, drugs to rejuvenate and increase longevity are still prized.

The Han dynasty (206 BC to 220 AD) saw remedies (including veterinary) recorded in handy booklets or Gansu, which were strips of bamboo or wood bound together. All herbal medicines were collected together in the Shen Nong Ben Cao Jing (the pharmacopoeia of Shen Nong) and classified into three categories:

• Upper: drugs that nurture life

• Middle: drugs that provide vitality

• Lower: ‘poisons’ used for serious disease.

The most noted physician of these times was Zhang Zhogjing, who divided diseases into six types: three ‘yin’ and three ‘yang’. His prescriptions aimed to correct any imbalances of these forces. He also contributed to acupuncture by drawing a map of meridians along which the body’s vital energy (qi) is said to flow. During this period, the theory of the circulation of the blood was described, and anaesthetics were used, based mainly on Datura. By the end of the Han dynasty all the elements we regard as vital to TCM were in place, and refinement went on throughout the Tang, Song and Ming dynasties.

During the Ming dynasty, Li Shizhen (1518–1593 AD) produced the classic herbal encyclopaedia Ben Cao Gang Mu. It took 27 years to compile and consists of 52 volumes containing 1892 medicines. It was translated into Japanese, Korean, English, French, German and others, and is said to mark the beginning of a cultural exchange between Chinese and Western medicine.

In the 20th century, TCM came under attack from Western influences. Missionary doctors translated Western medical journals into Chinese, and Chinese doctors who had studied abroad turned against traditional herbal medicine. However, after the 1949 communist revolution, the government of the new People’s Republic of China reinstated TCM and set up new medical colleges, intended to break China’s dependence on the West. The 3rd (or Cultural) Revolution of 1966–1976 brought culture to a standstill, and ‘barefoot doctors’ with no more than 6 months of training were sent to rural areas to replace the denounced ‘intellectual’ Westerners. Today, both systems coexist and even Western-style medical schools teach students TCM and acupuncture.

Concepts in TCM

Qi, the essential life force

Qi (or chi) permeates everything. It is transferable. For example, digestion extracts qi from food and drink and transfers it to the body; and breathing extracts qi from the air and transfers it to the lungs. These two forms of qi ‘meet’ in the blood and form ‘human qi’, which circulates through the body. It is the quality, quantity and balance of qi that determines your state of health and lifespan. Obviously, therefore, food and air affect health, so diet and breathing exercises are very important. These aspects of treatment will be considered first, before herbs are introduced. It is considered that the original vital energy, yuan qi, is gradually dissipated throughout life, so it is important to conserve it using diet, kung fu, breathing exercise and herbal medicine.

Yin and yang

These have already been mentioned as central to Taoism, and the theory of yin and yang still permeates all aspects of Chinese thought. Attributes of both are:

• yin: negative/passive/dark/female/water

• yang: positive/active/bright/male/fire.

Yin is considered to be the stronger: fire is extinguished by water, and water is ‘indestructible’. So yin is always mentioned before yang; however, they are always in balance. Consider the well-known symbol (Fig. 12.1

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