Written by Dr. Viv Rolfe
The weaving together of scientific herbal evidence and the extensive back-catalogue of traditional knowledge and practitioner experiences, is a recognised goal within the herbal community (1). Often, knowing where to look for good quality herbal research, and how to search for what is up and coming, can be quite a challenge. Online tools can be used to help search for clinical information, and there are a number of different types of article that are useful. The aim of this article is to provide a brief explanation of what these are, and how to search for them.
The best way of gathering evidence in a consistent manner regarding the effects (good and bad) of a herbal remedy on a group of people is through doing a clinical trial. To achieve a good quality trial, many methods need to be in place including randomisation, blinding, placebo-controlled (best summarised here (2)). People reading a clinical trial paper can look out for these buzz-words as a starting point for sifting out the higher quality papers from lower quality papers.
When several clinical trials have been completed on a subject, (for example with herbs such as Turmeric or Ginseng where there is an abundance), researchers might choose to pool the data and summarise the results from them in a systematic review. In essence a systematic review summarises evidence from a variety of experiments researching a common topic, in order to more accurately assess an outcome with as much evidence as possible. As with trials, these must follow a precise methodology to minimise the author’s bias from the process (best summarised here (3). Again, buzz-words for selecting the best reviews would be those that have used a specialist organisation (e.g. Cochrane Organisation, Joanna Brigg’s Institute), and those that have used validated tools to produce a high quality report (e.g. AMSTAR, PRISMA) or evaluated the trials that they have selected in a robust way (for example looking for risk of bias tools and other factors that signify the quality of a study). These are some simple pointers, and as the reader gets more familiar with clinical trials and systematic reviews, you will begin to understand the finer nuances.
So how to get started and search for stuff?
As the numbers of systematic reviews continues to grow, authors are As the numbers of systematic reviews continues to grow, authors are recommended to share their intended protocols on PROSPERO (4). Sadly this doesn’t stop many similar reviews being published, but it is a fun place to search for work that is ongoing. In the search box, a simple phrase like “Herb OR Botanical OR Plant” can yield a number of ongoing reviews. For example, there is an interesting study underway looking at the role plant compounds can play in suppressing sweet taste receptors in the mouth, and the protocol is clearly outlining the research question, searches and methods that the review will use (5).
If a review is complete and published, it should say so on PROSPERO, or you can search for the authors names in a second online database PubMed. This is a free tool from the US National Library of Medicine and it is a hub to search for scientific papers from around the world. Of course, of importance to the world of herbal research is the use of Asian journals, and a number of these are well represented. (Additional searches can also be done to retrieve more localised information (6). The simplest way to use PubMed is to use the ‘clinical queries’ search (7). On this page you can search for any herb and you’ll see articles relating to COVID-19 (a recent addition) alongside a list of other clinical studies; these studies include clinical trials and systematic reviews, although occasionally there is a stray article that has crept through the search strategy, but on the whole, it is pretty precise.
Another important thing to remember is that plant nomenclature is complex and everchanging. Thankfully the Medicinal Plant Naming Service (MPNS) at Kew Gardens fixes this problem. Here you can type in the name of a medicinal plant, and it will show you the synonyms and homonyms of this species including both common names and Latin binomials.
A fantastic feature that it has, is that you can search scientific databases for research without having to manually type in all of the different names of a plant. Sometimes plants have over 50 names so this saves a tremendous amount of time.
The steps are as follows using the example of chamomile:
- Go to Royal Botanic Gardens, Kew: Medicinal Plant Names Services
- Type in plant name Chamomile
- Select the most frequently used scientific name, in this case it is matricaria chamomilla
- Click search externally
- Click NCBI or Google Scholar (in this case we will use NCBI- Pubmed)
- Click Pubmed Central
- If you would like to search for a plant and a specific condition insert the condition in quotation marks as well. For example “Matricaria chamomilla” “Anxiety” .
- You can also search using all scientific names used for this plant by clicking this option on the right and following the same protocol
Once you start searching you’ll find there is a wealth of information out there. It is important to recognise that the assessment of herbs and preparations through these methods established by western medicine is problematic, where iOnce you start searching you’ll find there is a wealth of information out there. It is important to recognise that the assessment of herbs and preparations through these methods established by western medicine is problematic, where individualised natural preparations intended as a holistic approach are squeezed through the mechanics of looking at single ingredients for one biological target. However both scientific and clinical research methods are advancing to allow for more complexity through ‘omic technologies and use of big data. So it is likely in the future that these methods will reflect more of the spirit of herbal medicines to help with further integration and ultimately wider choices for the public regarding their health.
1. Roy Upton (2021) Can We Integrate Traditional Knowledge and Modern Science? (Part 7). Available: https://www.herbalreality.com/integrate-traditional-knowledge-modern-science/
2. Trish Greenhalgh (1997) How to read a paper: Papers that report drug trials BMJ 1997; 315 :480 doi:10.1136/bmj.315.7106.480
3. Trish Greenhalgh (1997) How to read a paper: Papers that summarise other papers (systematic reviews and meta-analyses) BMJ 1997; 315 :672 doi:10.1136/bmj.315.7109.672
4. PROSPERO (2021) International prospective register of systematic reviews. Available: https://www.crd.york.ac.uk/prospero/
5. Antonio Segura-Carretero et al (2021) Plant-derived compounds and suppression of sweet-related responses. PROSPERO 2021 CRD42021248971 Available: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021248971
6. Madhur Aggithaya et al (2015) Literature searches on Ayurveda: An update. Ayu. 2015;36(3):238-253. doi:10.4103/0974-8520.182754
7. PubMed Clinical Queries (2021) Available: https://pubmed.ncbi.nlm.nih.gov/clinical/