Comfrey: Looking at the Research

Last fall I wrote a blog on cinnamon, looking at the research, for the purpose of understanding some of the research that is being done on the herb. I would like to take a closer look at comfrey this time. There is a lot of caution out there around comfrey being used internally so for this time I chose a research paper that focused on the topical use of comfrey root in a cream.

Last time, when we looked at cinnamon I chose to look at a review paper. Review papers discuss the collaborated research from a number of different sources. Our paper on comfrey is not a review but a primary research paper, meaning the authors themselves did the calculations and provided the herb to the test subjects. I found this paper through Pubmed Central, where all articles are free to download in their entirety rather than paying for them.

comfreyWhen I am reading a primary research paper I do not generally read it in the order it is written. I first will read the abstract to see if the topic is what I think it is. Then I will read the conclusion/discussion before I go to the methods and then results sections. I find that when I know where the paper is going I am more effectively able to understand the methods section and determine if their process was valid. Often, the introduction only gives background information and can help you find other studies to look at. There is not generally new information there. Here is the main result quoted from the paper:

The 10% and 20% [comfrey root] creams reduced pain by 50.3% and 52.1% and stiffness by 44.1% and 56.9%, and improved function by 49.5% and 55.3%, respectively.

Going back to the methods section, the first thing that I looked for in this paper was what kind of extract they were using of comfrey. While the abstract mentioned that they used comfrey root, the methods section leaves this information out. The extract used was done by volume not by weight as most tinctures are made and the alcohol was 50% ethanol to 50% water.

comfrey-officinale-few-yellow-flowers-400Second, the preparation used included ‘eucalyptus oil.’ It is not clear if this is essential oil or an infused oil but I believe it is safe to assume it was essential oil. As herbal enthusiasts you probably can already assume that using the eucalyptus in the preparations would have some of the pain revealing action. The authors labeled the eucalyptus and other ingredients (not listed) as inert but there is no way from this study to know if this is an appropriate conclusion or not.

I would like to encourage you to read the paper linked above and see what other information you feel may or may not be appropriate for the study to achieve the conclusions they found. While we all know and love comfrey for pain and joint stiffness due to osteoarthritis it is important to understand how the research is being done not just accepting the facts as they come to us.


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