1 Phytotherapy in context
“Spoken stories were the living encyclopedias of our oral ancestors, dynamic and lyrical compendia of practical knowledge. Oral tales told on special occasions carried the secrets of how to orient in the local cosmos. Hidden in the magic adventures of their characters was precise information regarding which plants were good to eat and which were poisonous, and how to prepare certain herbs to heal cramps, or sleeplessness, or a fever.
The search for food by early peoples inevitably led to encounters with plants that were discovered to be either toxic or therapeutic – sometimes both (depending on the amount ingested and the constitution of the individual). The development of herbal medicine thus occurred alongside adventures in determining the diet, so that we might consider herbal medicine to represent a branch, or offshoot, of nutrition. Zysk and Tetlow (2001) have observed that: ‘The most traditional source of Ayurvedic medicine is the kitchen. It is likely that, at an early stage of its development, Indian medical and culinary traditions worked hand in hand with each other’. Beyond India, across the planet, we can suggest that the origin of the pharmacy lies in the kitchen.
The human relationship with medicinal plant chemicals is therefore a primary one. Homo sapiens emerged into a world long since populated with a great diversity of plant life with which our hominid ancestors already had intimate experience. To put things into perspective – we can compare the origin of our species, currently estimated at around 200 000 years ago, with the origin of the tree – and the now popular herbal remedy – Ginkgo biloba, which appeared some 200 million years ago. We tend to overlook, or take for granted, the fundamental essentiality of the plant–person relationship: just as we cannot live without sunlight, our health depends on plants.
The interaction between people and plants is, however, not straightforward. Rather it can be seen as a process of mutual adaptation, a dynamic evolutionary interplay. This deep engagement necessarily involves the full range of plant chemistry, running the gamut from attraction to repulsion, nutriment to poison. The ethnobotanist and professor of nutrition, Timothy Johns (1996), has described how the search for sustenance also laid the foundations for plant medication:
The properties of plants that make them unpalatable and toxic are the same properties that make them useful pharmacologically. In exploiting plant foods it is impossible to avoid their defensive chemicals, and I believe that in adapting to them our species has made them an essential part of our internal ecology.
The sense of taste is at the core, as the primary sensory engagement with medicinal substances at the point that they enter the body. In the Hippocratic tradition ‘eight qualities of taste’ are recognized: sweet, fatty, acid, bitter, pungent, salty, bilious and astringent (Ullmann 1978). These are similar to the flavours discerned in traditional Chinese medicine, where herbal agents are classed according to whether they possess such distinctions as sourness, sweetness, bitterness, saltiness, pungency, blandness and astringency. These categories are not abstract or abstruse rationalizations, but rather the representation of clear and direct sensory experience. Each particular taste is associated with certain properties. For example, in Chinese medicine: bitter herbs have ‘drying, reducing and downward-moving capabilities. (They) can dry Dampness and dissolve Phlegm … [and] reduce Heat from the internal organs’ (Yang 2002). This is a very practical set of correspondences, based on observation and experience. The taste of the herb is associated with its sensed and observed ability to, for instance, warm (pungency, as in ginger) or cool (bitters) the body, or to be drying (astringent) or moistening (saltiness) in character. This range of information provides a pattern of activity, which can then be mapped against, and applied to, patterns of illness. When the patient has a condition that is hot and wet in its manifestation (such as a fever accompanied by sweating), then the requirement for herbal treatment that is cooling and drying is obvious. Such reasoning is at the core of ancient medical systems and constitutes the experiential origin of therapeutics.
That is not to say that classification systems of this type have ever been straightforward or unopposed! Controversy over classifications and the difficulty of making fine distinctions in diagnosis and prescribing has been in evidence since ancient times, as a Hippocratic author (from around the sixth century BCE) demonstrates:
I am utterly at a loss to know how those who prefer these hypothetical arguments and reduce the science to a simple matter of ‘postulates’ ever cure anyone on the basis of their assumptions. I do not think that they have ever discovered anything that is purely ‘hot’ or ‘cold’, ‘dry’ or ‘wet’, without it sharing some other qualities … It would be useless to bid a sick man to “take something hot”. He would immediately ask “What?” Whereupon the doctor must either talk some technical gibberish or take refuge in some known solid substance. But suppose ‘something hot’ is also astringent, another is hot and soothing as well, while a third produces rumbling in the belly. There are many varied hot substances with many and varied effects which may be contrary to one another.
Careful judgement also needs to be exercised in determining when to encourage or oppose the expression of a disease phenomenon. For example, a low grade fever may need to be provoked into an acute manifestation with warming herbs in order to be fully expressed and thereafter fully healed. Suppression of a fever at an early or mild stage may be actively harmful. Therefore, traditional medicine is not exclusively allopathic (contrary in nature) but includes homoeopathic (similar in nature) elements too. The physician’s skill lies in knowing how to modulate the pattern of the disorder, drawing on a range of capacities as required.
Returning to taste, we can say that the intensity of sensation derived from a herb or food can provide general indications as to its potency of action, its safety profile and the dosage that might be appropriate for it:
A rough indication of the qualities of a food or herb is the strength of taste. This could be seen to represent the relative amount of Qi contained within the food or herb. Generally, mild flavoured foods are consumed as staples (grains and pulses for example), while foods and drinks with stronger taste (tea, coffee, spices and condiments, etc.) are used less frequently because they have more of a medicinal effect.
Mild flavours typically indicate a broad therapeutic window (i.e. a wide potential dosage range, suggesting the relatively benign nature of the substance) and hence suitability for long-term use in chronic disorders. Mildness occurs in herbal categories such as the ‘adaptogens’ (e.g. Astragalus membranaceus – huang qi) or the nervous ‘trophorestoratives’ (e.g. Avena sativa – oat straw). Strong flavours, conversely, are suggestive of a narrower therapeutic window (where the toxic dose is close to the therapeutic dose) and are more appropriate for short-term use and in acute disorders, e.g. the use of the powerfully bitter herb Hydrastis canadensis (golden seal) in sinus or gastrointestinal infections.
‘Mild flavoured’ foods and herbs may alternatively be classed as ‘bland’. The sinologist, Francois Jullien, has used the motif of blandness to provide insight not only into Chinese medical thinking but into the philosophy of Chinese thought in general:
First, one accepts the paradox: that to honour the bland – to value the flavourless rather than the flavourful – runs counter to our most spontaneous judgement … But in Chinese culture, the bland is recognised as a positive quality … When the seemingly paradoxical becomes self-evident, when the value of the bland has changed signs, we begin to feel more comfortable with Chinese culture. When we begin to apprehend the stirring – beyond our ideological reflexes and cultural conditioning – of the possibility of a positive notion of the bland, we have entered China: not into its flashiest or most sophisticated realms, but into what is most simple and essential.
Our direct sensory experience of the world shapes how we interpret it. Jullien’s study helps to demonstrate the connection between taste and world-view: between physiological taste and aesthetic taste. In this analysis, blandness is a desirable quality of foods and herbs since it denotes those that are likely to be safe and suitable to take more frequently (or at higher dosage). Bland foods (such as grains, pulses, nuts and seeds – also known as ‘earth’ foods in Chinese medicine) are considered to be staples since they are gentle, easily digested and generative of a point of stability and potential, around which smaller amounts of more pronounced flavours may be consumed. The correlation is that a bland life, which is to say a moderate life, is the most sustainable way of living and one that can accommodate occasional eruptions of disorder or intensity – either planned or unplanned. Here we detect the ‘feast’ that is at the root of ‘festival’. The traditional yearly cycle of generally ordered yet seasonally varying routine interspersed with occasional festivals/feast days provides an opportunity for short periods of stimulation, indulgence and free expression arising from a ground of moderation. While this pattern of living can be criticized as a means of maintaining feudalism and oppressive social control, it need not be constructed to this end – it also tends to spontaneously arise in successful indigenous cultures.
It is clear that the opposite scenario (i.e. the current mode of living in the ‘developed world’ where the bacchanal has shifted from sacred event to mundane lifestyle) is unsustainable, i.e. a day-to-day life of general stimulation/indulgence interspersed with short intense periods of moderation (going on a diet; checking-in to the detox clinic), is not robust enough to persist over the long term. Seen from this position, conventional medicines can be understood as a strand of an over-stimulated culture since they share the same intense, strong, unrelenting nature – unsubtle, single-gear agents that are integral to, and which fuel and enable an unsustainable mode of living. Herbal medicines, by comparison, appear relatively bland – notwithstanding the fact that several of conventional medicine’s most potent remedies are based on plant compounds (e.g. diamorphine from the opium poppy, Papaver somniferum). In reality, plant medicines represent a complex spectrum of healing influences from the totally innocuous to the potentially lethal. Recent mainstream discourse on herbal remedies has tended to oscillate between the poles of this range – either plant medicines are too weak to offer the prospect of genuine healing effects or they are too toxic to be further contemplated as possibly valid medicines. Paradoxically, in societies that have drifted so far from nature and so deeply into an immoderate way of living that the continuing viability of the human (and many other) species is now threatened, herbal medicines (a potential part of the solution to an unsustainable lifestyle) are increasingly seen as wildly unpredictable and potentially dangerous entities. Yet this is not a paradox, since cultures that have distanced themselves from nature to the point of becoming nature-phobic will tend to fear and distrust the agents of nature (uncomprehending of their complexity, resistant to their meanings) such as herbal remedies.
In order for herbal substances to be accommodated within the dominant nature-phobic medical culture they need to be transformed or disguised. The most radical form of transformation takes place when the multi-compound complexity of a whole herb is reduced to a single ‘active constituent’, thereby actually becoming a ‘real’ conventional drug (i.e. a single, simple chemical compound). Whole herbs are not easily included into biomedical practice but the more a herbal remedy is disguised to look and feel like a conventional drug, the greater will be its chance of acceptance. This means that it should ideally be a chemically standardized extract of a solitary herb, presented in a processed coated pill form that is branded, packaged and corporatized. Ernst and Singh (2008) paternalistically advise that herbal medicine users only take single plant remedies, making sure to avoid traditional mixtures of herbs (herbalist’s ‘concoctions’); in their view only standardized preparations of herbs are to be permitted, and these should be bought in a packaged pill form off a pharmacy shelf. What if we were to suggest that herbs could be picked for free from the wild? Presumably Ernst and Singh would be horrified by the idea, yet their protestations would not travel well outside of the UK where they are based – it would be difficult, for instance, to persuade Danes, Germans and Italians that it is ill-advised to pick wild mushrooms! Following such drug-centric, nature-phobic advice directs one to products in which the herb tends to lose its taste and wherein it can no longer be savoured: odourless, tasteless, intangible – it ceases to have any connection with food and consequently enters into a changed relationship with the digestive system and, hence, the whole organism.
Despite adjustments in its preparation and presentation, the process of assimilating the herb into the dominant scientific medical culture cannot be completed until a corpus of evidence has been accumulated to mark the change in status from ‘herb’ to ‘drug’. In the course of undergoing research, the plant will have to inhabit the diagnostic and prescriptive territory of conventional drugs so that, for instance, Hypericum perforatum (St John’s wort) must cease to be a ‘nervine tonic’ used as an aid in depleted and exhausted nervous states and instead become an SSRI-like antidepressant, only to be used for mild to moderate depression. This type of shift in the meaning and significance of the herbal agent is seen by some as representing the rational validation of plants as therapeutic agents while others consider that it debases, diminishes and perverts the true nature and potential of herbal medicine. The transformation from traditional remedy to ersatz-drug in this type of case means that a profound opportunity is missed. In processing the plant to fit the language and classification systems of medical textbooks and prescription manuals the irony is that, while these texts do not recognize the concept of ‘nervine tonics for depleted and exhausted nervous states’, doctors and patients readily do! Doctors see people in this predicament daily but have little if anything to offer them from the conventional materia medica. Failure to consider the traditional understanding of the properties, indications and cautions for herbs, treating them instead as novel substances without a history, whether due to carelessness, ignorance or arrogance, commonly results in needlessly narrowed and warped interpretations of their capacities.
When researchers approach herbs from the perspective of positivist science, a one-way process generally follows with the herb being assimilated into the conventional model. Little or nothing is learned from the story that the herb brings with it. Typically, when attention is paid to traditional records and practitioners, or even where sophisticated original background ethnobotanical research has been conducted with native healers, pharmaceutical company funded research is only ultimately interested in generating leads that may give rise to a new and marketable drug – at which point the ‘back story’ is ditched. In his book Prospecting for Drugs in Ancient and Medieval European Texts, Holland (1996) talks of: ‘The use of folk beliefs and traditional healers as a short-cut to the discovery and isolation of pharmacologically active compounds …’, as opposed to promoting renewed use of the herbs themselves. The assumption is that herbal medicines are of no value in their own right, although they might provide clues that enable the production of ‘proper’ drugs. Why not just run trials on the herbs themselves and, if the old herbals are proven to be correct, then promote the wider use of herbs in medical practice? In answering that question, fiscal as well as scientific bias needs to be considered.
The absolutist nature of positivist science is typified by Dawkins (2003) who asserts that there are no such entities as ‘conventional’ and ‘complementary and alternative medicine’ (CAM) but merely ‘medicine that works and medicine that does not work’. He is confident that if so-called CAM practices (such as herbal medicine) are proven to work by means of double-blind randomized placebo controlled trials (RCTs) – if they are able to ‘pass that test’ – then ‘mainstream medicine would simply adopt them’. This is a view of biomedical substance, process and assimilation of cartoon-like quality, that displays either stunning naivety or wilful perversity. In this monotheistic view, biomedicine is portrayed as the only legitimate form of medicine. It has the capacity to incorporate techniques and materials into its scope but only when these comply with its own scientific normative standards – there is no need to question these principles, only to rigorously apply them. In order for CAM practices (or aspects of them) to enter the big tent of biomedicine they merely need to show their passport at the flap – suitably stamped ‘RCT’. In fact biomedicine cannot eat CAM practices whole – they first need to be prepared into a suitably digestible form via marination in approved forms of research. Yet even long steeping of this kind may still fail to render them appetizing. Would Dawkins be surprised to find that doctors (in the UK at least) are not prescribing the heavily research-validated St John’s Wort for depression? For all its evidence-base, this herb somehow remains foreign, it fails to fit in, and meets with the kind of incomprehension and xenophobia that all too commonly characterize the position of the dominant culture in response to the immigrant. Despite what Dawkins has suggested, it appears that the world of biomedicine is not value free.
Since the dominant medical drug model is inflexible, herbal medicines must change their form and divest themselves of their attached traditional rationales if they are to be incorporated into it. We will return to this territory later as we discuss the varieties of phytotherapy and the ways in which herbal practitioners have engaged with or opposed the biomedical project.
In Ayurvedic medicine, as in other traditional systems, taste is central to appreciating the qualities of herbs as well as foods. Joshi et al. (2006) equate ‘taste’ with the Sanskrit word ‘Rasa’ which ‘refers to a complex totality of experience arising from all the perceptory interactions of the material with sensors in the mouth and nasal passages, taste buds, olfactory and chemesthetic receptors’. The notion of ‘Rasa’ incorporates six primary tastes, similar to those already mentioned in ancient Graeco-Roman and Chinese medicine: sweet, sour, salty, pungent, bitter, and astringent. Each primary taste is said to be composed of specific combinations of the elements and exerts particular influences on the Ayurvedic humoural system (i.e. the three ‘doshas’ of kapha, pitta and vata). For example, the sweet taste is composed of earth and water, it increases kapha and decreases pitta and vata. Further differentiations of taste are drawn in Ayurveda, including the concepts of ‘virya’ (which identifies thermal, tactile and other effects with eight descriptions that are formed into four complementary pairs: hot–cold, unctuous–dry, heavy–light, dull–sharp) and ‘vipaka’ (which describes three types of aftertaste: sweet, sour and pungent).
Beauchamp et al. (2005) found that the drug Ibuprofen and a compound found in extra-virgin olive oil (oleo canthal) both caused a similar stinging sensation in the throat. Although possessing different chemical structures, both agents share similar anti-inflammatory activity as COX-1 and COX-2 inhibitors. Joshi et al. (2006) refer to this research, seeing it as offering modern confirmation of the value traditionally placed on taste, and suggesting that: ‘Using “taste” as an additional tool, new phytochemicals of desired therapeutic activity might be more rapidly identified’. Taste is a pharmacological detection tool, since different tastes are triggered by different chemical compounds: bitterness relates to compounds including iridioids, sourness to certain acids, sweetness to polysaccharides, astringency to tannins and so on. In this way, even the most primary, non-technological relationship between people and plants can be rendered to the service of biomedicine. Alongside the plundering of the knowledge of traditional healers and of ancient herbal texts, the very sense of taste itself can be exploited to reductive pharmacological ends. In these realms, the balance between justification and appropriation of herbal medicine is played out: proponents of herbal medicine can use traditional and pharmacological evidence to justify the validity of herbal medicine, while biomedicine can use the same means to appropriate it. This paired agenda is one of the key sites of tension in the interface between herbal and conventional medicine.
A pharmacological perspective reveals a large overlap in the types of chemical compounds found in both foods and herbal medicines. Some substances may be considered to belong in both categories, e.g. garlic and the culinary herbs and spices such as basil and cinnamon have a place in the kitchen and the dispensary. A chemically-based approach to distinguishing between plants as foods and as medicines may begin by acknowledging the considerable overlap between the two groups before making the general distinction that foods tend to be rich in primary metabolites of nutritional value (macronutrients and micronutrients), while medicinal herbs tend to contain less nutritional compounds but a high proportion of secondary metabolites (such as alkaloids, saponins and volatile oils). Foods – when carefully selected and prepared – are generally, and necessarily, extremely low in toxicity and able to provide nutrients to maintain growth, repair and the maintenance of normal physiological functions. Medicinal herbs provide a spectrum of agents from benign to toxic in effect, which can have an adaptive effect on physiology – modulating the response to challenges including those deriving from pathology. This distinction between foods and medicines is essentially the same as that made by the Persian physician al-Majusi (late tenth century), which was in turn based on the writings of Galen (BCE 129–c.216?), which states that:
Ullmann (1978) further describes al-Majusi’s distinctions between foods and medicines, which are based on how the body changes, and is changed by, these two types of substances. Al-Majusi’s perspective is divided into four categories of relationships:
This systemization continues to provide a good model for appreciating the differences between, as Ullmann terms them, ‘remedies’ (i.e. herbal medicines); ‘poisons’ (certain toxic herbs and conventional medicines); ‘remedial food-stuffs’ (those possessing gentle therapeutic activity); and ‘food-stuffs’ (which build the substance of the body). The ability to distinguish between plants that are foods and those that are medicines (as well as those which straddle both categories) in this way has been crucial to human survival. This understanding is also vital in other species, as the science of zoopharmacognosy is revealing (for an introduction to this area, see Engel 2007). The importance of this knowledge is testified to by the number of documents (known as ‘herbals’) from earliest times, dedicated to listing and explaining the therapeutic properties of naturally occurring substances – principally botanical material. A stunning example is the Ebers Papyrus (discovered by Georg Ebers in the 1870s), which gives some 700 remedies for a wide variety of conditions. This ancient Egyptian text, dating from around BCE 1550, is considered the oldest medical text extant. Numerous other herbals are left to us from around the world from Ancient Greece and Rome, Mediaeval Europe, India, Central America and China.
We might now reflect on the nature of the relationships between plants and animals, including humans, particularly with regard to how these have influenced the production of secondary metabolites, and how tolerance and utilization of these compounds has developed.
According to Wynne-Edwards (2001): ‘Evidence of coevolution of plants and herbivores is abundant’. Animals have used plants for food and plants have responded by developing mechanisms to deter them. While some plants may accrue positive gains from being consumed once they have developed seeds (the animal can then spread the seed in useful manure-wrapped deposits), they are at risk of being destroyed without benefit if eaten before this point. Some plant defences are physical (e.g. thorns) but most are chemical. Many chemical defences produced by plants taste unpleasant to us (e.g. intense bitterness) – the unpleasantness is the deterrent, while our retention of this sense of unpleasantness helps to protect us from consuming too much. This poses palatability challenges when working with herbal medicines, and relates to such folk wisdom as: ‘The worse the medicine tastes the better it is for you’.
… mammalian herbivores often consume a diverse diet composed of sublethal doses of chemical defences or carefully consume only the tissues that are least toxic to them … (they) can also evolve detoxification mechanisms that allow them to consume specific plants in spite of their chemical defenses …
Beyond this, animals have evolved to use plant defence chemicals to their advantage, often for the same purposes as the plants themselves. Plants, for example produce antimicrobial compounds for their own needs, which can be used by humans to destroy our bacterial and fungal infections. Plant secondary metabolites may serve multiple purposes within the plant itself, for instance: alkaloids act as a deterrent to herbivores but are also involved in absorption of nitrogen from the soil; flavonoids help to prevent infection in plants but also protect them from UV radiation and play a role in regulating growth. It is important to note that the plant–person relationship works in both directions, animals and plants adapt in response to each other. A major human cause of changes in plant chemistry is that of domestication of food plants. This has led to changes in their chemical composition, including the reduction of more aggressively acting or toxic secondary metabolites. Wild potatoes, for example, are generally too unpalatable and potentially harmful for human consumption but some of their inherent toxicity has been reduced through careful selection and cultivation.
The origins of herbal therapy then, lie very deep – through co-evolution with plants we are hardwired for a dynamic interaction with plant secondary metabolites. This relationship is not limited to the purely physical level. O’Doherty et al. (2001) have shown that both pleasant and unpleasant tastes influence the amygdala (a brain structure associated with emotional and mental activity) and the psychoactive (especially hallucinogenic) properties of some plants can be considered as a particular category of deterrent innovation that have influenced humans profoundly – shaping beliefs about the world.
Much of the literature on herbal medicine (most pertinently the growing body of texts considering herbal safety issues) seems ignorant of this primeval dance. We have learned not only to tolerate a great range of plant chemicals but beyond this we have also been successful in turning many of them to our advantage. We can utilize plant resins in stimulating leucocytosis for instance, or triterpenoid saponins from plants such as ginseng (Panax ginseng) to improve our energy, endurance and stamina. Such gains are the remarkable fruits of our long interplay with the botanical realm – we spurn them at our peril.
At a micro-level, we can discuss the relationship between people and plants in chemical and pharmacological terms: referring, for example, to triterpenoid saponins and their ability to induce intracellular generation of adenosine triphosphate (ATP) leading to enhanced energy, endurance and stamina. The macro-tier however, has to do with the relationship between Homo sapiens and, in this example, Panax ginseng. Many herbs contain triterpenoid saponins but the particular herb in question, in each specific case, is sufficiently chemically and structurally different to be classified as a distinct and separate species. For instance, although they both contain triterpenoid saponins, Panax ginseng and Siberian ginseng (Eleutherococcus senticosus) do not have exactly identical therapeutic actions since they do not share precisely the same chemical make-up. Successful herbal medicine is practised with an appreciation of both the pronounced and the subtle distinctions between herbs that share key chemical constituents.
Some herbal authorities decry the tendency to focus on herbs at the micro-level at the expense of the macro-aspect. One does not have to choose between the two, however. Both levels of scrutiny possess their own validity and each may be impoverished when it stands alone. Some critics of the phytotherapy approach have associated it with an undue and unbalanced focus on reductive pharmacological scrutiny of the plant. This need not be the case, since it is perfectly possible to view narrow (but potentially helpful) pharmacological insights in the context of a broader appreciation of the whole plant. We will return to the discussion of phytotherapy towards the end of this chapter.
The comparison of micro-scrutiny via focus on areas such as phytochemistry with macro-perception of the plant in its entirety is pivotal in appreciating the distinctions between the conventional medical utilization of plant products and that of herbal practitioners. It is a tenet of herbal medicine that whole herbs must be prescribed rather than the isolated active constituents derived from them. This is the difference between making a medicine directly from strips of, e.g. willow bark (Salix spp.) itself as opposed to extracting acetyl salicylic acid (aspirin) from it. When liberated from the context of the (many) other phytochemicals present in the plant a single active constituent will not behave in quite the same way as the whole plant. Typically, the isolated constituent exhibits one pronounced quality of the whole plant (taken from among many less prominent ones) but does so more aggressively and with greater potential to generate adverse effects. Occasionally, an isolated constituent may show activity that could not be anticipated from knowledge of the whole plant. Commonly then (but by no means exclusively), use of the whole plant compared with isolated active constituents will demonstrate activity which is:
(Note: Many of the adverse effects generated by conventional drugs signify attempts at detoxification by the body – this includes many rashes, digestive upsets, headaches, nausea and vomiting, etc. Herbal medicines are more ‘food-like’ in their complexity and are less likely to trigger pronounced elimination responses.)
‘Whole’ is, however, a debatable concept. If we infuse or decoct a herb in water, or prepare it in other ways such as by using alcohol as an extractive medium (in making herbal tinctures), we do not have every constituent in the resulting liquid, since there will be lots of plant material left behind in the pan or press. The only way to get every constituent into the body is to consume the whole herb, e.g. as a powder. Even then, some constituents will deteriorate or transform while the herb is being dried, processed or stored (albeit that some such changes, in particular cases, may serve to enhance the efficacy of the herb). Then again, whatever the number or quality of constituents present in the preparation, it is uncertain how many will actually cross the body’s membranes in order to exert physiological effects. Nonetheless, we can still draw a picture of differing chemical complexity between herbal preparations (which will contain hundreds of different chemical compounds) and conventional medicines – whether plant-derived or otherwise (which are generally single compounds). Herbal medicines are chemically complex, whereas conventional drugs are chemically simple.
This vision would come to pass and to fruition in modern pharmacology as alchemy gave rise to chemistry. In zeroing in on ever-finer detail however, the bigger picture is obscured: the most prominent active constituents in medicinal plants are contextualized within a package of many other, more subtly acting, constituents and co-factors that, far from being ‘dross’, may play a significant role in shaping the overall actions of the plant. Medicinal plants, the herbal practitioner contends, are not mixed ores in need of refining but, rather, the finished article.
Appreciation of the chemical complexity of the ‘whole’ plant presents pharmacological challenges both technically and conceptually. The complexity can extend to such an extent that a single herb may have a great number of different actions. For example, yarrow (Achillea millefolium) is said to be a: diaphoretic, antipyretic, peripheral vasodilator, anti-inflammatory, spasmolytic, bitter tonic, styptic (haemostatic), antimicrobial, anti-haemorrhagic and vulnerary (wound healing) herb (Bone 2003). It is only when one appreciates the great diversity of chemical composition in plants that one can understand or accept the possibility that a single herb might encompass the breadth of actions that would require assembly of a large part of the conventional pharmacy to be matched. It is in the nature of herbs, as ‘polypharmacies’ in and of themselves, to influence more than one ‘target’ at a time; their effects are diffuse, complex and wide ranging. Such therapy enables (and, to be optimally successful, requires) a broad approach to the patient that allows for the emergence of unique healing pictures since the outcomes of this type of medicine cannot be fully predicted due to the wide variety of body systems that may be modulated. To practice herbal medicine then, it is essential to be comfortable with a degree of uncertainty regarding the form of results (but in which practice of medicine is this not also true?). The key to successful herbal practice is to be highly sensitive and responsive to the patient’s changes (no matter how subtle) at each consultation, varying the prescription accordingly. Herein lies a central feature of herbal practice: as the patient’s picture changes over time, the herbal prescription they receive will also change to reflect and positively adapt or propel these developments, since a course of professional herbal treatment is a dynamically evolving rather than static process.
A herbal medicine needs to be considered as a different type of pharmacological entity to a conventional drug. The latter are simple chemical compounds, whereas herbal medicines are, at least in terms of the whole plant starting material, highly complex organisms. In fact, it is beyond the power of current pharmacological knowledge to completely analyse and track the chemistry of whole herbs – or indeed to come anywhere near achieving such a goal. The chemical complexity of herbal medicines increases of course as several herbs are combined in a particular treatment – comprising perhaps 25 herbs in a classical Chinese medicine formula, for example. The chemical make-up, or at least the relative quantities of each compound, in individual species of herbs also varies depending on growing and processing factors, which include:
Attempts have been made to tame the wild complexity of herbs by standardizing preparations with regard to key active constituents (it is impossible to standardize a herb on all constituents – many of which have not yet even been elucidated). Although many herbal practitioners are wary of any attempt to manipulate the chemistry of herbs, standardization in its most useful manifestation merely consists of measuring key constituents and blending different batches to provide a specified minimum level of one or two compounds. The complex nature of plant chemistry is reflected in the practice of herbal medicine with regard to the consultation. The approach to the patient reflects (and is consistent with) the nature of the medicinal materials used:
• Herbal practitioners claim to ‘use the whole plant to treat the whole person’, with allowance being made for the complexity and variability of the person, just as must occur (to some degree) with the plant.
• Typically, long consultation times in modern herbal practice provide space to explore the patient’s history across its full range, giving credence to information that might in conventional medical consultations be considered ‘dross’.