What do you mean ‘evidence based’?

Out there on the interwebs it’s a polarised planet. People are shouting in echo chambers about their distinct world views on politics, religion, and science. In the seemingly lovely land of yoga and natural health, there’s just as much argy bargy between factions as elsewhere. One of the main issues centres around what we mean when we say something ‘lacks evidence’ or conversely that something is ‘evidence based’. The truth is rather messy but I’ll do my best to explain what we mean by ‘evidence based’ and how that is defined in the intersectional evolving fields I’m part of.

Evidence Based Practice


evidence based practice

From nursing and health sciences we have this model of Evidence Based Practice that is a great starting point. Evidence based practice (EBP) is defined as ‘the conscientious use of current best evidence in making decisions about patient care’ (Sackett, Straus, Richardson, Rosenberg, & Haynes, 2000).

Where patient/client values intersect with a practitioner’s clinical experience and that of relevant ‘experts’, plus there is current literature supporting the use of that intervention for that type of condition and demographic, we have evidence based practice. Without the input of current peer reviewed research we may still have decent practice and patient/client satisfaction but it is not evidence based practice in the way the current health science paradigm expects.

For naturopaths, nutritionists, herbalists, yoga therapists and others engaged in complementary therapies, there’s a vast body of knowledge that’s been passed down to us in what amounts to a fairly ad hoc, teacher-student lineage style. In fact, this is the same process that conventional medicine has been going through. The idea of evidence based practice is relatively recent in all schools of medicine. The traditional ways of knowing were founded on understanding the basic mechanism of disease coupled with clinical experience. In that way, the whole continuum of health from surgery to homoeopathy share a history, if not a philosophy, of practice that lacks scientific evidence.

Now we have a situation of ‘us and them’, with evidence based practitioners taking a stance of moral high ground, over those who continue to see benefits in a more traditional approach. I’ll leave the medical model to be debated from within, and focus on complementary therapies including my main practice modalities of nutrition, herbal medicine and yoga therapy.

The Hierarchy of Evidence


Glossary of some of the terms in the hierarchy:

Evidence Guideline: a systematically developed statement designed to assist clinician and patient decisions about appropriate healthcare for specific clinical circumstances.

Meta-analysis: a systematic review that uses quantitative methods to synthesize and summarize the results.

Randomized control clinical trial (RCT): randomly allocates participants into an experimental group or a control group and follows them over time for the variables/outcomes of interest.

Systematic Review: a summary of the medical literature that uses explicit methods to perform a comprehensive literature search and critical appraisal of individual studies and which uses appropriate statistical techniques to combine these valid studies.

In terms of research methods, randomised controlled trials (RCTs) are often considered the ‘gold standard’ in research, however they are notoriously rare in natural health fields. The reasons are not just about a lack of funding directed at this kind of research (in fact there’s increasing investment in supplements research, mostly by commercial interests), but also about the way natural medicine is practiced. The individualised protocols typically given do not lend themselves to a reductionist model. So while there is a body of pharmacokinetic research into Chinese herbal medicines (still critiqued for lacking scientific rigour), and ample epidemiological nutrition science, the translation of this evidence into practice requires a more nuanced and holistic approach.

Herbal Medicine Evidence

A lot of work has been done in the study of herbal medicines. From the Rig Veda of India, and the Egyptian papyri Antiquarium of around 3000 BCE, humans have used plants for their medicinal properties. In Europe and the Americas, a vast historical knowledge base exists, in both written and oral form. In Australia a growing interest in indigenous medicine has also unveiled sophisticated use of plants for healing. Current clinical use of herbs still relies heavily on this traditional wisdom, even as many practitioners attempt to embrace evidence based practice.

When pharmaceutical drugs are developed from plant based medicine, the active constituent is isolated and replicated, so that precise dosages can be calculated.  This is in contrast to the variations found in nature, and in the supply of medicinal herbs to herbal medicine practitioners. Attempts to standardise herbal extracts are controversial, and even if each bottle of a named herb was identical in content, when prescribed there is a wide range of dosing strategies and rationales.  From ‘drop dosing’ to ‘mega dosing’, teas, tablets and tinctures are typically prescribed in combination, making analysis of effects very challenging.

So while there is evidence of efficacy for many herbs, in fact the German Commission E provides authoritative information on studied herbs, there is also evidence of adverse effects from herbal medicine. In 2013 Posadzki, Watson and Ernst published in the journal Clinical Medicine, an article called Adverse effects of herbal medicine: an overview of systematic reviews. They found that of 50 systematic reviews of 50 different herbal medicines there were a number of adverse effects, including some very serious such as liver and kidney damage, colon perforation, even death.

The great complexity of herbal medicine makes it challenging to translate evidence into practice, and with potent physiological effects possible, it is wise to take a cautious approach to herbal medicine, especially when used in conjunction with other pharamaceuticals, as potentising or blocking of drug actions is possible. A well known example is that of Hypericum perforatum, common name St John’s Wort, a herb indicated for mild depression amongst other uses. Many people self prescribe this herb, with tableted forms available in health food shops and pharmacies. However St John’s Wort acts on a biochemical pathway through the liver that increases the metabolism of drugs. That means any medication taken alongside St John’s Wort will clear the body more quickly than expected, minimising the effectiveness of the drug.

Still think natural = safe? Herbs are powerful medicine and should be given the respect they deserve. While they may save lives in the absence of conventional medicine, they are generally not well indicated in combination with conventional drugs. If you are seeking herbal remedies, see a qualified practitioner, hopefully one who keeps up with current evidence, is a member of a professional body, and has insurance! It’s also very important to tell your doctors if you are taking any herbal medicines, even if you think they are gentle and safe, as interactions may impact your care.

Nutritional Medicine Evidence

Since it’s unethical to ask humans to eat only one food over a period of time, nutritional science is also very complex. Observational studies of populations and the prevalence of chronic disease is one approach, and the epidemiological studies certainly provide evidence that informs nutritional guidelines for preventive health. Studying the chemistry of individual foods is as fraught as herbal studies, and given that self report measures of food frequency are notoriously inaccurate, it’s perhaps not surprising that nutrition is a hotly contested and controversial area.

What is proven is that nutritional needs vary across the lifespan, and that most people do not meet the minimum nutritional guidelines, such as eating 5 serves of vegetables each day. In fact, evidence based nutrition is pretty straightforward and some would say, rather dull. Why would anyone bother with 5 serves of veg, 2 fruit, a handful of lean protein, a serve or two of dairy or an alternative, and some complex carbohydrates, when the loudest voices in nutrition are shouting about miracle cures for complex multi-factorial conditions such autism and cancer?

It’s not that we don’t know what will optimise nutritional status and well-being for most people, it’s more that people have a complex relationship with food. We have some evolutionary tendencies to maximise our intake of flavour, fat and energy content that don’t serve us well when our lifestyles are mostly sedentary and we can access a days worth of calories without even standing up (drive through anyone?).

In terms of disease specific dietary protocols, ‘experts’ continue to argue, and vested interests within dietetics are widely blamed. Individuals metabolise food differently, so even a recommendation as seemingly straightforward as to decrease simple carbohydrates to manage blood glucose fluctuations will need to be assessed in individual cases.

We may be overfed yet undernourished in terms of nutrient density, so many people turn to supplements. the evidence for taking vitamin and mineral pills is flimsy at best. Occasionally a study is published showing that people with a certain condition have lower levels of a certain nutrient, however that does not mean that taking a supplement of that nutrient will prevent the disease. So we are left with #jerf meaning Just Eat Real Food, or as the journalist Michael Pollan famously quipped ‘Eat real food, mostly plants, not too much’.

fruit and veg carbs

Mind Body Medicine and Yoga Therapy Evidence

In the canons of yoga we have claims of antiquity, with texts from the Vedic era (1500 BCE – 500 BCE) translated to support the views of different communities, likely to reflect socio-political agendas as much as any benevolent goal. In more recent times (20th century) we have had charismatic ‘expert’ teachers making claims of specific benefits for different asanas (postures) and pranayama techniques (breathing exercises).

Thankfully we also have an exponentially expanding body of literature demonstrating how very effective yoga and meditation are for people with a variety of health conditions. Strong evidence exists for using yoga as a therapeutic intervention in conditions including cardiovascular risk reduction and depression. There are also rigorous studies showing yoga as a useful complementary therapy in anxiety, sleep disorders, pain syndromes, diabetes, cancer of many types and especially breast cancer. What stands out in the yoga therapy literature is that even when results were insignificant for some measures, the self reported quality of life scores always improve.

Client Centred Care

Improvements in quality of life are meaningful, and this speaks directly to the aspect of evidence based practice that includes listening to clients/patients. Regardless of whether there is sound statistical data to support every clinical decision, we are well served to keep the client themselves front and centre. By consulting, coaching, actively listening and applying all our ways of knowing, we can collaborate with the people we aim to serve to provide the best possible care, informed by all forms of evidence.

So as we work towards improving natural medicine practice, and bridging the paradigm divide between evidence based practice and traditional knowledge, we need to be ready and willing to accept not knowing. There’s a wisdom in uncertainty. It may not draw the big crowds, you may not make your millions on selling herbal diet pills, but you will have integrity and be of genuine service to others, by placing yourself in the vulnerable position of not knowing everything.

In this way, complementary therapists of all modalities can embrace complementary ways of knowing, and provide excellent evidence informed services that improve well being in the community.