Evidence for complementary medicines: the value of science and traditions

medicines under magnifying glass

Brenda Davy takes a look at the the evidence base for CMs

Complementary medicines have existed for centuries and have provided the basis for many of the formulations of ‘conventional’ medicines that are widely available today.

More commonly referred to as vitamins, minerals and herbal supplements, these medicines have become part of our mainstream healthcare practice in Australia as well as globally.

The evidence for complementary medicines can be either ‘traditional’ or ‘scientific’. Each of these requires rigour and the allowable claims coming out of each type of evidence differs.

Many complementary medicines have a plethora of traditional evidence. This is a well-recognised form of evidence accepted by the Therapeutics Goods Administration and allows specific traditional-use claims to be made.

Traditional evidence for complementary medicines refers to a history of use of at least 75 years (considered to represent three generations of use), although sometimes extends to thousands of years, within a particular traditional medicine paradigm. This could refer to traditional Chinese medicine, Ayurvedic medicine, or Western herbal medicine, amongst others.

Most cultures developed systems to treat their sick and injured, so there are many different paradigms for traditional medicine. Some traditional medicine systems are easier to trace this development, due to the long history of detailed written records, such as found with traditional Chinese medicine.

Others are more difficult to trace, and further work is required to create accurate records to prevent this information from being lost.

Many traditional ingredients have a well-established period of widespread traditional use which is extensively recorded in recognised evidence sources for traditional medicine such as materia medica, monographs and publications from various international regulatory authorities.

The rigour required for traditional evidence is substantial and more about this can be found on the TGA website.

‘Scientific evidence’ also exists for many complementary medicines. Scientific evidence refers to quantifiable data and includes: clinical trials in humans; epidemiological evidence; animal studies; and other evidence of biological activity.

Scientific indications are usually supported with data from relevant scientific evidence, and there are many high quality sources of scientific evidence, including:

  • peer-reviewed original clinical research in well cited journals;
  • systematic reviews of the clinical research relating to particular subject areas;
  • unpublished studies or ‘Propriety research’ (as long as they meet the required criteria); and
  • secondary sources or non-clinical studies.


The advantage of referencing peer-reviewed research is that these studies have typically been subjected to rigorous methodological evaluation that ensure that the results are robust and valid.

The methodological design is a key feature for determining the quality of the evidence. If the parameters used in the study are not precise, then the results will be of less value, however a study conducted using accurate measures, well-matched controls, and appropriately adjusting for confounding factors provides far greater confidence in the results (and therefore the evidence and efficacy of the product) than an uncontrolled, or poorly measured study that fails to differentiate between correlation and causation.

The rigour required for scientific evidence is also substantial and more about this can be found on the TGA website.


Brenda Davy is the Strategy Manager Complementary Medicines, Australian Self Medication Industry.

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