Herbalist Danny O’Rawe discusses a holistic approach to contemporary research using the Evidence House.
Introduction to evidence-based medicine
Critics of herbal medicine sometimes lead the public to believe that they should avoid herbal remedies because there is a lack of evidence about the safety or efficacy of medicinal herbs. They often resort to the somewhat exhausted mantra that “just because something is natural does not mean it is safe” (2,3,14, 28). This is on the face of it an accurate assessment, but it may also be a half-truth. It could equally be suggested that because something is natural it is more likely to be safe (due to its longevity of use without incident for example) rather than something which is unnatural, such as a synthetic drug made in a laboratory with all its inherent risks and unwanted side effects. Indeed, it is because of the latter, that the general public often seek a ‘natural alternative’ in the first place.
The general longevity of use in traditional practice over many centuries suggests the vast majority of herbal medicines when used appropriately by practicing herbalists are as safe as fruit and vegetables (indeed many of them are fruits and vegetables), with only a few stronger herbs employed in limited dosages. Part of the problem is that some researchers chose to ignore the existence of the professional herbalist who is trained to flag any potential contraindications which might assuage at least some of the perennial concerns they raise. Instead, some prefer to put across their conflated concerns of an unsuspecting public stepping into the mire, and rather than suggest that the public consults with a professional herbalist; they play on fears and generate uncertainty (13; 16). The objective of this type of criticism is to create a sense of doubt in the public eye, but is it all just smoke and mirrors?
While it’s true to say that some herbs such as Atropa belladonna are dangerous in the wrong hands, access to such plants is legally controlled and these herbs are unavailable to the general public. And while unsuspecting amateurs harvesting from incorrectly-identified species in the wild may cause problems for themselves, such misadventure is not in any way connected to professional herbal medicine. By and large, the majority of herbs used by herbal practitioners are tried and true over long periods of time. A small selection of herbal medicines may be considered more medicinally “potent”, but the discerning herbal practitioner uses restricted doses and fixed durations of use for such herbal preparations and is trained to be aware of any potential toxicity.
The deconstruction of semantics aside, we are still left with the question – is there a lack of evidence for herbal medicine? In order to put this question into context, we might begin by examining the term “evidence” itself. Critics of herbal medicine believe that herbal medicine can only be understood through certain types of evidence.
In a court of law the defendant or prosecution presents corroborating evidence for particular statements to establish the foundations of their arguments. This corroborating evidence may come from diverse sources. The origins of evidence are less important than the strength of such evidence to convince a judge and jury. But what if the judge demanded that only evidence gathered from the City of London could be considered, even if the events around the case occurred outside the City of London? You would be correct to think that such a hypothetical situation would be ludicrous.
Evidence-based medicine
The term evidence-based medicine (EBM) became popular in the 1990s (31). It presents the case that all medical interventions should be “evidence-based”, with the double-blinded randomised controlled trial (RCT) considered the gold standard in clinical research. Systematic reviews and meta-analyses of RCTs (peer review) became the pinnacle of the new evidence hierarchy. The clinician could then use this information to best inform their clinical judgement. However, evidenced-based medicine in this particular reading has a number of confounders and inconsistencies. Firstly, it implies that there was no evidence before EBM or if there was it was circumstantial (coming from outside the City of London in our earlier hypothetical scenario).Secondly, it implies that evidence can only be assessed in a certain way and that this evidence is better than other types of evidence such as expert opinion. The imposing hierarchy of EBM is summarised in Figure 1 below:
On first glance it seems odd to put expert opinion at the bottom of the pyramid and place systematic reviews at the top. The concept of defining evidence in this way may well be a noble attempt to eliminate bias from influencing clinical decision making, but this itself is predicated upon the erroneous belief that bias can be completely eliminated. It seems more likely that bias may only be limited through these processes but only in carefully controlled laboratory conditions (creating internal validity) which unfortunately have little connection to what happens in the real world (lacking external validity).
The RCT is a methodology which is used in testing the efficacy of new drugs, treatments and health care services. The use of RCT research is considered highly effective by its supporters because it is thought to minimise allocation bias (Nunan, Heneghan and Spencer, 2018). The significant characteristic of RCTs is that trials usually include a control experiment alongside the main treatment. These are known as placebo-controlled studies. They are used in comparing changes recorded in the active treatment group in order to ascertain that the placebo group that was not included in the treatment does not react in a similar manner. This serves the purpose of proving whether the active treatment actually had an impact on the active study group. In this way it can be established whether or not a new drug is superior to placebo. But how do you establish a placebo?
Comparing a drug to a placebo in an RCT sometimes implies that the placebo effect has a fixed value, say 30%, so the new drug must be equal to or greater than placebo in terms of safety and effectiveness and yet placebo effects may be greater or lesser than 30% depending on many factors. For example, there may be more than one placebo effect depending on the circumstances, so placebo controls may actually potentially increase bias in some cases (9).
But let’s assume in a double blind randomised controlled trial that a new drug is found to be greater than placebo and no major adverse reactions are recorded. The trial and methodology should then be independently replicated and a statistically similar result would be expected. Replication trials should mimic the methodology of the original trial, and statistically similar results would either validate the original study or bring it into question. When we speak of gold standards, this extra layer of scrutiny would help to strengthen the clinical trial process. In turn systematic reviews and meta-analyses might include replication trials as specific inclusion criteria.
What if the RCTs are not independently replicated? The results may be unreliable, and the primary research data would be flawed? What if researchers later conducting a meta-analysis only include certain RCTs (some of which may be flawed) and not others (which may not be flawed) in a peer review? In that case secondary and tertiary research could also be flawed, casting shadows over the whole process.
What of researcher conflicts of interest; study cohorts which are not representative of the general public; unrealistic sample size; lack of preclinical screening for participants; use of unrealistic dosages or durations of use; and statistical bias? There are many problems with such a rigid methodology, if full checks and balances are not put in place.
Professor John Ioannidis put this into stark perspective with his highly influential paper Why Most Published Research Findings are False, which has become the most cited research paper of all time (19). Ioannidis argues that due to a lack of replication trials, statistical incongruence and the initial “truth” of a research question, most research may be false. If Ioannidis is correct, could this culture of false or erroneous data account for increasing iatrogenic events which now sees modern medicine as a leading cause of death in annual all-cause mortality statistics? (22) This would imply that there is a crisis in the current EBM paradigm.
On the other hand, expert opinion at the bottom of the EBM pyramid (Figure 1) might be in need of a paradigmatic reappraisal. Imagine a physician who has seen thousands of patients and developed successful healing strategies over many years in real world situations. Would it be advisable to value their expert opinion above the results of a potentially flawed clinical trial?
David Sackett, nominated by his peers as the “Father of EBM” for his pioneering work, describes EBM as an amalgam of the best systematic research, expert opinion and the patient’s rights and choices (29). If we follow Sackett’s description, we see a tripartite approach, not a single approach that favours filtered over unfiltered information but a multifaceted approach which values systematic research alongside expert opinion, and importantly brings in the vital component of patient experience and opinion.
Patient-centred care has become a popular term in modern medical parlance, and yet many patients do not feel satisfied by the care they receive under the current medical model. Patient satisfaction is an important and commonly used indicator for measuring quality of care. Disempowerment of the patient may occur because of long waiting times; the all too brief consultation process where empathy does not occur and where key information can be missed; but also because of side-effects and/or a lack of efficacy of prescribed medications and procedures (17).
Taking these comments into consideration, there are problems and obstacles within the current paradigm of EBM. We must also consider how useful this methodology is to herbal medicine in particular?
The RCT process is designed for pharmaceutical drugs within a reductionist paradigm, where a candidate drug with a single therapeutic target is examined. Clearly, the multi-constituent nature of herbs (with multiple therapeutic targets) does not fit easily into this model. Some researchers have tried, occasionally successfully, to put herbs through such scrutiny, but the cost and time involved may hardly be worth the effort, especially when it is often not reflective of or does not contribute to an understanding of the practice of herbal medicine.
Could the RCT process be reconfigured in such a way so as to examine the protocol a herbalist uses in clinical practice for a particular condition, and compared with an orthodox treatment, rather than testing a single herb or constituent against an imagined placebo? Might this provide evidence of the efficacy and safety of herbal medicine if it is designed to reflect actual practice?
Systematic research can be useful provided it is relevant to herbal practice. Where it is not relevant to practice it may be considered as “background information”. The danger of an obsessive approach to EBM and a paradigm enthralled to scientism is that it may also eclipse other important strands of evidence.
Building an evidence house
What if the playing field is levelled and we consider other strands of evidence equally and without imposing an EBM-like hierarchy? I propose an “evidence house” model for herbal medicine research on egalitarian lines, where each room yields key information which can establish a foundation of evidence upon which to build. In contemplating this approach I decided that I would examine those stems of evidence upon which I have drawn for practical information and which have since informed my practice and led to successful outcomes for my patients.
While some information offers very basic clues, my approach here is not be overly concerned with the initial ‘strength’ of the data, but rather whether or not these clues may in time provide practical, safe and effective outcomes in clinical practice through comparison and consolidation of other multiple strands of data.
I am alert to the potential weaknesses in such a model in a reductionist sense but I stress that a perceived deficiency in one room may be supported by strengths in another and that it is a combined or holistic approach that might provide the best evidence for herbal medicine. For example, a traditional practice may provide the original clue on how to use a particular herb or treat a certain condition. On its own, this reference to a traditional use may be unsatisfactory but what if the clue is supported by evidence from one or more of the other rooms in the evidence house? And what if the original clue is not supported?
The six “rooms” for building the proposed evidence house are as follows.
- Tradition
- Folklore
- Organoleptics
- Phytochemistry
- Systematic Research
- Empiricism
Imagine an architect’s blueprint of a ground floor in which all 6 rooms share a “hallway”, meaning that they connect or integrate with each other holistically in the evidence “house”. Each has, or could be considered as having, various strengths and weaknesses and there may be ways of evaluating each of these for “structural integrity” and creating better insulation in time as the model is developed through further research.
All of these rooms alone have yielded clues which in time have led to practical results in my clinical practice, and this is the main criteria upon which I will draw in presenting this model. Some rooms have helped more than others but I reiterate that the room itself is not hierarchically more important as a singular evidence base. What is important is how one room connects to the other rooms and how the collective gathering of information from multiple rooms leads to an evidence base for safe and effective health outcomes. This approach combines quantitative and qualitative data and both objective and subjective viewpoints. Let us consider each room as if we are viewing the house.
Tradition
From the beginning of my dedication to herbal medicine, I learned from a tradition. By tradition I mean historical texts which were not lay commentaries but rather, practical guides written by professional practitioners intended as the furtherance of knowledge. These herbals were textbooks in schools of medicine across the world until relatively recent times, written by learned physicians and based on their own experiences and observations. This differentiates tradition from folklore (the “room next door”) because it is based on the experiences of practitioners whose vocation in life was dedicated to the healing profession. These early physicians, in the cases of Dioscorides or Avicenna for example, were also well-travelled and drew upon other traditions outside of their locality, comparing and contrasting, amalgamating or rejecting different aspects of information and practice over long periods of time. Their written wisdom is then passed down the generations to new students and apprentices who continue the tradition. In the case of the aforementioned authors, this process may occur over several centuries. Such authors, then, are not only important to herbalists but to the history of medicine itself.
Over the passage of time, we find new herbals appearing; sometimes blindly or lazily following the classic authors without scrutiny; sometimes challenging concepts or contributing new wisdom. The corpus of herbals is actually immense but it is possible to look at certain authors whose significance and contributions were such that they become historical beacons. It is possible to trace the use of a single herb over the centuries by giving precedence to such classical texts in the Western Herbal Tradition to show continuity of medicinal uses along with fresh approaches and scholarly commentary. Such a process has been neatly established by herbalists already (32).
One of the confounders in this approach discussed by these authors is the identification of a plant. Different common names, incomplete descriptions or poorly drawn figures may be misrepresentative of a plant when comparing one author with another in historical texts and cause dilemmas of identification and for tracing continuity, at least until the times of Linnaeus and the development of the standard Latin binomial classification of genus and species. Such a pitfall has also been negotiated by a number of scholars such as Beck (6)in the case of Dioscorides, or (1) in the case of Avicenna, and is no longer as big of a problem problem in modern times with international acceptance of Latin binomial classification. In fact there is a research project at Kew Gardens being conducted to solve this very issue. A researcher can now chart the history of a plant’s medicinal uses over thousands of years.
Importantly, the use of what herbalists refer to as “energetics” is also a crucial and fundamental aspect of herbal medicine tradition because its application, irrespective of the herb or herbs used, is still pertinent today. This is all the more relevant because it is precisely this heuristic tool of energetics that allows for individualised protocols within a holistic paradigm. Compare a bespoke strategy such as this with the apparent one size fits all approach of allopathic medicine.
Energetic differentiation establishes principle qualities of disease using basic concepts such as hot, cold, dry or damp and variations thereof. Similarly, a herb or herbal formula can also be categorised as hot, cold, dry or damp or variations thereof. Part of the practitioner’s traditional role is to access the patient and decide which of these categories best relates to the patient’s symptoms in terms of having an excess or a deficiency of these basic qualities. A patient could be too cold or too hot, but they could also be cold and dry, hot and dry, or hot and damp (but not cold and hot, or dry and damp. which are mutually incompatible). These conditions can progress and change so that someone who starts off too hot can become too cold in time. The practitioner must use pattern recognition to deduce the initial imbalance as well as the progress of that imbalance. Once recognised through good case taking and diagnostic examination the physician uses herbs in a treatment of opposites, according to the appropriate action of the herbs. In rudimentary terms, the “strength” of the herbal protocol would also be surmised from the stage of disease progression as well as the patient’s individual predicament by using a system of degrees.
A person with the common cold may feel cold and shivery or hot and sweaty. This would require a different approach in each case. Compare this to allopathic medicine where there is no differentiation and both patients may receive the same antibiotic treatment.
The traditional holistic approach does not end here.
The patient is also given adjunct advice whose remit is to challenge the potential causes of their condition, thereby treating both causes and symptoms in a holistic root and branch approach. In the Hippocratic school of thought, for example, we find reference to the 6 non-naturals – six areas of life over which the patient has some influence and which ultimately affects their health. The non-naturals include fresh air; motion and rest; sleeping and waking; food and drink; excretion and detoxification and the passions/ emotions. Incorrect diet and lifestyle choices may lead to contra-naturals, or symptoms, in the Hippocratic model. In a sense then, traditional herbal medicine is not so much a system of healthcare as the practice of ‘life-care’.
This basic view of herbal tradition describes fundamental principles which are as valid today as they were in centuries past. By researching a herb in classic texts at various junctures in time, the researcher discovers uses, preparations, specific indications, energetics, dosages (though not always), contraindications, synergies with other herbs and other practical information developed over immense periods of time. This tried and true information can be applied practically, and it is a route by which many first find themselves intrigued by the possibilities of medicinal plants.
Folklore
Although folklore is certainly a part of Tradition in its wider sense, it can also be treated separately. While the herbal Tradition can be discussed in terms of herbal medicine as a vocation and a profession, there are also myths and legends particularly in rural areas where local people (folk) carry on ancient oral traditions about the local use of plants (lore). Such lore is often dismissed as archaic, superstitious or at best anecdotal but such accusations belie a partiality. Common people often filter their understanding of the world through the lens of local customs, beliefs and religions which create cultural meaning and identity. In dismissing folklore, one may also be dismissing the entire culture that goes with it!
A modern reader wanting to understand such a culture from an ethnobotanical perspective might embrace local customs, beliefs and religions as a means to set the scene for a wider cultural understanding within which such customs evolve. For example, a piece of lore might call for the use of a herb for a particular condition but this may be accompanied by prayers, songs or magic rituals which the modern reader may feel is out of time or incongruent within the current scientific paradigm. Therefore because of this “superstitious” misunderstanding of folk tradition in general, any suggestion of a folk cure being effective is often dismissed.
The American linguist Kenneth Pike saw a similar discrepancy in the anthropological sciences. He coined the terms Emic and Etic in his seminal 1967 text Language in Relation to a Unified Theory of the Structure of Human Behaviour to describe the difference between looking at the worldview of another through your own cultural lens to “establish an objective, scientific approach to the study of culture” (Etic) and looking at it within the context of “grasping the world according to one’s interlocutors’ particular points of view” (Emic). Emic assumes the role of “native perspective”; Etic the role of an “arm’s length” approach (27).
However, some scholars have begun to compare ancient descriptions with modern interpretations. This is an instance of taking a clue from one room and supporting it with clues from another. For example, researchers compared Ginger (Zingiber officinale) in Persian folk medicine with indications from modern research, concluding that modern uses of Ginger confirmed the traditional folk uses of Ginger. The research also revealed that there were other properties from traditional folk use which have yet to be elucidated in a modern context thereby offering more new clues for medicine (21).
In order to consider folklore as an evidence base I refer to my original criteria – does it yield practical information which can lead to safe and successful clinical outcomes? Ethnobotany is the study of human relationships to plants. A study of this subject may yield useful information when assuming an Emic approach, using Pike’s descriptors. This does not mean such a study is without its own inherent problems. There may be discrepancies with the correct botanical identification of the plant in question if it is known by a local name which cannot easily be equated to its modern binomial taxonomy. There may be an absence of cultural context in regards to the customs and rituals which may accompany it. There may also be a dilution of the original practice over the generations. These confounders do not prevent the discovery of practical information.
For example, researchers considered a number of plants from 10th century Anglo-Saxon texts for their potential use as antimicrobials. In the study, several preparations of Agrimonia eupatoria, Arctium minus and Potentilla reptans were screened for antimicrobial activity against gram-positive and gram negative bacteria (Watkins, Pendry, Sanchew-Madina and Corcoran, 2012). The texts examined had previously been considered as having “little or no value to medical understanding” (8). The authors cross-referenced from several translations of the Anglo-Saxon texts to negotiate potential confounders and keep close to the original clinical indications. All plants demonstrated antibacterial efficacy and the authors concluded Anglo-Saxon texts may be a good source for rediscovering plants lost to current herbal practice (34).
An ethnobotanical study of Allen & Hatfield’s Medicinal Plants in Folk Tradition: An Ethnobotany of Britain and Ireland (2004) which has been gathered from multiple sources including the work of the Irish Folk Commission based on oral tradition, concluded that many of the plants studied may be potential sources for new therapies (10).
Ethnobotany is unfortunately an area of concern where indigenous information is stolen to discover interesting compounds for novel drug discovery. The term ‘biopiracy’ is sometimes used to describe this theft of cultural intellectual property from native cultures (4) If used respectfully, it offers data which can be cross-referenced with other ethnobotanical uses in other parts of the world, much like historical research of traditional use in established herbals, and provides clues which can be filtered through other rooms.
Organoleptics
The term organoleptics refers to the use of the senses to acquire information. The skills of the wine taster or the perfumer who can detect and describe multiple flavours or scents are well known to modern culture. In the history of herbal medicine we also find reference to a concept known as the Doctrine of Signatures which infers that the shape of a plant or plant part may resemble a part of the body and so it must be intended for healing that part, by the signature of God. However, this may be an oversimplification. The shape may be important, but so too is the taste of the herb, the scent of the herb, its colour, its texture, its location and so on. Rather than fixating on shape alone, information may be gathered and consolidated from multiple sensory experiences. For example, a sweet-tasting plant may reveal the presence of polysaccharides or a salty taste might reveal the presence of mineral salts such as magnesium and potassium. A bitter taste may reveal the presence of alkaloids. An aromatic scent might reveal the presence of terpenes. A yellow colour may indicate a connection to the liver; a red colour may indicate a connection to the heart and so on.
Philippus Theopastrus Bombastus Von Hohenheim (1493-1541) also known as Paracelsus wrote his famous comments on signatures in the text Supreme Mysteries of Nature (1656). Jacob Boehme (1575-1624) wrote Signatua Re-rum (The Signatures of All Things) which was a contemporary work. TheGiambattista Della Porta (1535-1615) text Phytognomonica (1588) is even earlier, and mention must also be made of William Cole (1626-1662) and his book The Art of Simpling (1656) which serve as early works in regards to organoleptics, however these concepts and methods are much older than the 16th century! They developed independently across centuries in multiple cultural centres – Europe, China, America, India and Africa (12)). Many ancient tribes discovered the medical properties of plants in manners such as this, gaining empirical data from sensory information. The concept of entrainment with plants does not literally mean “talking to plants” but implies the tacit gathering of information between two living beings through sensory engagement.
Spending time in the company of plants is what Aristotle would call “learning by doing”. Developing the senses in this way may take years to learn but in time allows one to elucidate constituents and also to intuit from other information to create tacit patterns of association that can only come from direct encounters. Modern research also confirms organoleptics. De Medeiros et al., 2015 found significant associations between both taste and therapeutic indications (p<0.001); and smell and therapeutic indications (p<0.0001). (23) provide evidence for a highly significant association between the organoleptic properties of plants and the use of these species as medicine. Geck et al., 2017 show that organoleptics guide the choices of the therapeutic actions of medicinal plants.
Organoleptics is something of an art form but with careful practice, the novice can gain useful information of a practical nature, but for some this may take decades. However, initial clues from inspecting a plant, no matter how strange they may seem at first, can be compared with clues from other rooms.
Phytochemistry
It may seem tangential to consider phytochemistry as a singular source of evidence; however the effects of a plant’s primary and secondary constituents are now largely established in terms of their effects on the body. Taking an unfamiliar plant and researching its chemical composition allows a fundamental understanding of what a plant might do medicinally, once its phytochemistry can be elucidated. This information can be found in research databases and with practice via organoleptic techniques. In the absence of historical record or clinical trials, knowing a plant’s phytochemistry can provide an understanding of both therapeutic qualities and potential cautions if toxic constituents are present.
Phytochemical analysis such as high performance liquid chromatography (HPLC) involves both qualitative and quantitative analysis of plant chemistry. While qualitative analysis is concerned with the presence or absence of a compound, quantitative analysis accounts for the quantity or the concentration of the compound present in the plant sample (15).
Several phytochemical databases already exist such as Phytochem and Duke’s, documenting qualitative and quantitative levels of primary and secondary compounds in plants. Considerable research has been done into singular constituents. For example, alkaloids are now known to have a notable physiological effect on the body in general because they have a structural relationship with neurotransmitters such as dopamine or acetylcholine (33). Another family of phytochemicals, flavonoids, are similarly well documented and some constituents such as the polyphenolic compound quercetin have demonstrated antioxidant, antifungal, anti-carcinogenic, hepatoprotective, and cytotoxic activity (5).
When working with an unfamiliar plant, perhaps one which has little historical information or research, information as to its potential medical uses can be gained by knowing the range of secondary metabolites present and whether they are water soluble (hydrophilic) or fat soluble (lipophyllic) which would inform of the most appropriate solvent to use for crude extraction, depending on the intended actions.
One confounder, and perhaps the bane of this approach, is to see one constituent as having more importance than other constituents (much like the question if one type of evidence is superior to another). This is reductionism at work where value is placed on a single compound and medicines are standardised to meet very specific levels of this compound because it has been previously found to have a certain effect in cell lines for example. The original medicine is thus modified, and may be considered a phytopharmaceutical. A case in point here may be Ginkgo biloba leaf, which does not have a long history in herbal medicine but systematic research has tended to use standardised extracts in past research and so some promote the standardised extracts accordingly. But, is there more to Ginkgo than gingkoflavones?
Plants generate compounds in the wild to deter pests and diseases or in reaction to its overall environment. The traditional use of a herbal medicine has been the use of the whole herb, plant part or crude extract where there will be seasonal and locational variability in constituents. A plant’s medicinal actions occur when a combination of phytochemicals interacts with the epithelium on ingestion. It is the combination of actions, not one action in particular, that creates the healing effect. Indeed, when singular compounds are extracted side effects may ensue because a compound may be toxic or non-toxic depending on the presence of other constituents.
Phytochemistry can help to corroborate ancient uses in the absence of systematic research. Organoleptics can help to identify constituents and effects in a similar way. This is a good example of how the interrelationship between each room helps to improve the overall structure of the evidence house.
Systematic research
Modern forms of research such as double blind randomized controlled trials are not wholly applicable to herbal medicine because of their reductionist philosophical underpinning. A standard trial tends to investigate the effects of one compound on one molecular target. This is unsuitable because herbal preparations contain multiple constituents with multiple molecular targets. I have already discussed some other inherent problems earlier. However, clinical trials can be designed in such a way so as to evaluate the herbalist “package” (the in depth consultation, the bespoke formula and tailored advice) and its effects on a particular health condition. For example, a pilot study (n=45) was conducted by herbal practitioners to assess the effectiveness of professional herbal practice in the treatment of menopausal symptoms. All participants completed the study. The treatment group (n=15) demonstrated a statistically and clinically significant reduction in menopausal symptoms compared to controls (n=30). Reduction in symptoms for the treated group was 9.05 points greater than that for the control group, CI 5.08-13.03, as were changes in vasomotor scores (mean 1.81, CI 1.00-2.62). Libido increased (mean 0.69, CI 0.38-0.99) in the group receiving herbal treatment (18).
Another study (n=120) into the alleviation of menopausal symptoms used a herbal formula containing Chamomilla recutita, Foeniculum vulgare and Crocus sativa (25). The formula was tested against placebo in different dosages in a randomized triple blind study. After 12 weeks of daily treatment there were significant improvements in physical, psychological and urogenital domains in group B who had taken a dose of 1000 mg, 120 mg, 60 mg of the aforementioned herbs in drop form, whereas improvements in symptoms were less significant in the other dosage groups (Madhavian, Najmabadi, Hosseinzadeh, Mirziaean, Aval and Esmaeeli, 2019). Such a trial is informative about dosage as well as the particular herbs that could be used to treat menopause. Bringing a greater emphasis to qualitative approaches helps to unpack other aspects of the herbal package, such as patient centred care through empathy and the length of time herbalist consultations typically afford (11).
Studies such as these are appropriate because they inform about herbal practice. Other studies which, for example, utilise a single isolated compound on a susceptible inbred animal at unrealistic doses are being geared towards the development of pharmaceutical drugs and have no bearing on actual practice. Unfortunately, background information such as this is sometimes used to justify or refute usage.
Qualitative studies, for example using questionnaires to access patient perceptions may also be valuable. Mixed-method research which utilises both quantitative and qualitative disciplines may also yield useful information, but the main criterion for any systematic research applies here – does it ultimately inform about herbal practice?
Empiricism
If we consider the EBM pyramid in its current form as a hierarchy of evidence, we may ask who decides which type of evidence is superior and which type of evidence is inferior, and what criteria are used to make these distinctions? On first glance it appears that these distinctions are made through an epistemological bias which favours one type of knowledge above another. It seems ironic that what we consider to be “expert opinion” is ranked at the very bottom of the EBM pyramid. The term “expert” can also be misleading because it suggests complete knowledge of a subject which is not possible, but what is implied by EBM is that knowledge gained through empiricism is somehow inferior to knowledge gained from rationalism and quantitative data. The relegation of empirical knowledge in this way reveals an epistemological bias which may undervalue traditional herbal medicine (20).
Empiricism is the theory of knowledge which claims that most or all our knowledge is obtained through sensory experience over time, rather than through rational deduction (24). Therefore knowledge gained a priori is considered by empiricists to be inferior to knowledge gained a posteri in philosophical terms. Practitioners of traditional herbal medicine gained knowledge over the ages largely through empiricism. It is only with the development of reductionist philosophy, such as the mechanisation of the body as promoted by Descartes and the scientific method as espoused by Bacon that rationalism became prominent and increasingly dominant as a philosophical paradigm.
However, in herbal medicine empiricism always tends to the individualisation of treatment. Conversely, in reductionist medicine the individual patient is labelled with a disease (machine with broken part) and the emphasis is on more universal treatment protocols. Nonetheless a consequence of this approach may be to confound the concept of patient centred care within the current reading of EBM.
A holistic approach considers that a body is an interconnected whole with multiple influences that can affect any particular part. A “broken part” may therefore not be at fault in and of itself, nor are things always down to genetic “bad luck” (though of course with some conditions this is inevitable). Rather illness is often caused by an ongoing homeostatic imbalance in one or more systems of the body. To focus solely on the perceived “broken part” misses this wider reality. It can also be argued that most diseases are consequences of poor diet and lifestyle choices (30). To focus on “broken parts” as being self-responsible confirms rational medicine’s place as a system for a masking of symptoms rather than a removal of causes, and so confutes the perception of patient centred care by neglecting the bigger picture.
Rational philosophy contends that empiricism is subjective and that different observers may have different interpretations of the same object. The rationalists argue that elimination of bias, at least insofar as this is possible, helps to remove the doubt that may be caused by these conflicting views. Yet, by disengaging with causative factors and avoiding a holistic approach, the patient is not wholly treated, leaving room for error. It is argued that a better approach may therefore be a combination of rationalism and empiricism as practiced by the 2nd century Roman physician Galen (35). Indeed, central to the argument for an “evidence house” for herbal medicine is that we draw on multiple sources of evidence without preference.
What has become known as ‘practice-based evidence’ places greater emphasis on the experiential approach where the practitioner gains knowledge by working directly with patients rather than theorising about them. The practitioner learns over time what does or doesn’t work in real world conditions. After treating a number of patients with the same condition or similar symptoms, the practitioner learns to understand the triggers and drivers which lead to a particular imbalance. In time the practitioner also notices that the same herbs or herbal combinations and particular adjunct advice may often be indicated for this condition. This empirical knowledge is therefore an important evidence base that is generated over time. It is the foundation upon which many of our classic herbals were written. The case-series which documents the herbal treatment of a condition in multiple patients is an evidence base that can be developed from such empirical data.
Practice-based evidence also bears some hallmarks of a long term clinical trial. Recently, researchers examined what are referred to as N=1 trials which incorporate much of the rigour of clinical trials, but are designed for individual patients. Individualising treatment interventions and outcomes in research designs is consistent with the movement towards patient-cantered care, according to the authors (7).A more inclusive approach to evidence also encapsulates qualitative data from patient observations and narratives, creating space for involvement and therefore patient empowerment.
Conclusions
To ascertain evidence for the safety and efficacy of herbal medicines by systematic research alone is in and of itself a limited and limiting process. Such reductionism is inconsistent with the holistic paradigm of herbal medicine. However, one form of research and evidence can be complimentary to another. A double blind randomised clinical trial may back up a historical use described in a classic herbal for example (26). An ethnobotanical use may provide hypothesis for clinical research and so on. Part of the problem with modern research into herbal medicine though is the focus on singular constituents perceived as active ingredients rather than the vocational practice of herbal medicine itself and what it has to offer. While the study of phytochemistry provides insight it is best served by focusing on the matrix of compounds rather than a singular compound. It can also help give weight to historical observations or folk practices.
In this more complex assessment of herbal medicine, we may be better served by drawing on a holistic perspective. The evidence house offers multiple rooms of information which connect into each other to form a whole foundation. Each room may lead the researcher to practical information which can deliver successful outcomes, although each room taken alone has its own pros and cons. Information from one room can go some way to offsetting the limitations of another room in a complimentary manner. This prevents epistemological tensions and allows for a greater appreciation of traditional herbal medicine.
Further research could be done into each room and a potential weighting, the strength or weakness of evidence, could be quantified for each room but this may be a slip towards reductionism. Rather, a researcher might consider that where there is an obvious weakness in one room, there may be strengths in other rooms. Drawing on all of these areas, and perhaps others not mentioned here, answers the question on how to access the safety and efficacy of a herbal medicine while attempting to avoid the clash of incongruent paradigms.
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