Health: Ayurveda and evidence-based research

Dr K K Aggarwal


There are six types of pieces of evidence accepted in the literature.


  1. Pratyaksha: What Is seen or observed? These are observational studies and accepted in the scientific community.
  2. Anumana or the evidence based on the inference of a defined hypothesis
  3. Upamana is the evidence based on the analogies
  4. Arthapathi are the pieces of evidence based on circumstantial evidence
  5. Anulupdhi is evidence based on the theory of negation
  6. Shabda is undisputed evidence as written in textbooks and taught to us


Let us take an example: Neem or Azadirachta indica is a good antiseptic


  1. Pratakysha: I would look for any observational study
  2. Anumana: I will look for any double-blind study In the literature
  3. Upamana: As per Ayurveda any plant which is bitter in nature will have anti-Pitta qualities
  4. Arthapati: Circumstantial evidence and Anupalibdhi, a piece of evidence by negation.
  5. Shabda: Would refer to Sushrut Samhita references as a gold standard.

An Ayurveda doctor will follow the Shabda evidence, but a modern medicine doctor may like to get Anumana as the evidence. But both are accepted as a piece of evidence.



  1. Primary (original) research involves data that are collected from individuals or clusters of individuals, with clusters defined by physician, clinic, geographic region, or other factors.
  2. Within primary research one should consider the hierarchy of evidence to minimize the risk of bias
  3. For studies evaluating therapy or harm, well-conducted randomized clinical trials are superior to observational studies, which are superior to unsystematic clinical observations
  4. Questions regarding benefits (and harms) of intervention are best answered with randomized controlled trials; whereas questions regarding risk factors for disease and prognosis are best answered with prospective cohort studies.
  5. Systematic reviews and meta-analysis are best for answering single questions (the effectiveness of tight glucose control on microvascular complications of diabetes). They are more scientifically structured than traditional reviews, being explicit about how the authors attempted to find all relevant articles, judge the scientific quality of each study, and weigh evidence from multiple studies with conflicting results. These reviews pay particular attention to including all strong research, whether or not it has been published, to avoid publication bias (positive studies are preferentially published). Systemic reviews and meta-analyses
  6. Summaries and guidelines –represent the highest level of complexity. Ideally, guidelines are a synthesis of systematic reviews, original research, clinical expertise, and patient preferences. At their best, summaries and guidelines are a comprehensive synthesis of the best available evidence, from which the guidelines themselves follow. Guidelines should, therefore, be based on a critical appraisal of the relevant original research and systematic reviews. There are several examples of multiple guidelines on the same topic making contradictory recommendations


The accepted standards for guideline development include:


Rely on systematic reviews


Grade the quality of available evidence


Grade the strength of recommendations


Make an explicit connection between evidence and recommendations


Strength of the recommendation


A recommendation is a strong recommendation to do (or not do) something, where the benefits clearly outweigh the risks (or vice versa) for nearly all patients.


Number 1 reflects a strong recommendation. A weak recommendation is made either when risks and benefits are more closely balanced or are more uncertain. Number 2 reflects a weak recommendation.


Quality of evidence


Assessment of evidence quality in GRADE reflects confidence in the estimates of benefits, harms, and burdens.


GRADE can be implemented with either four levels of evidence quality or with three levels such that the “low” and “very low” categories are combined.


Three levels use a letter (A, B, or C) for high-, moderate-, or low-/very low-quality evidence.


High-quality evidence typically comes from well-performed randomized controlled trials or other overwhelming evidence (such as well-executed observational studies with very large effects).


Moderate-quality evidence typically comes from randomized trials with important limitations or from other study designs with special strength.


Low-quality evidence typically comes from observational studies or from controlled trials with very serious limitations. Very low-quality evidence typically comes from non-systematic observations, biologic reasoning, or observational studies with serious limitations.


Based on the above we must come out with the strength of evidence and quality of evidence for every Ayurveda treatment.

Let us review Azadirachta Indica in the PubMed


  1. There are 2467 studies on the subject
  2. There are over 138 mentions in heading
  3. There are 92 RCT
  4. 308 systemic reviews
  5. 30 observational studies



From modern medicine point of view, Azadirachta indica will have Grade 1 A in terms of scientific evidence that it has medicinal properties.