Dear Herb Companion,
I am writing in regard to your article in the October/November 2001 issue on the toxicity of comfrey with its pyrrolizidine alkaloids (PAs). I would like to see some positive claims published. Is it not possible that only isolation of this single alkaloid causes it to become toxic to the liver? It would be a tragedy to take this best of all healers off the market.
I have been a constant user of comfrey salve and poultices since 1978 and in 1980 I began making healing comfrey salve, using every part of the plant, including the root (and other healing herbs from my garden). I use it daily as a night cream and for sprains, open wounds, or any injury that needs healing. The healing power of this herb never fails to amaze me. In addition, I am a heart patient and had to take medicine to lower cholesterol. Because this medication can cause liver damage, I?was routinely blood tested. After four years, my liver enzyme increased so I elected to go off the cholesterol medicine and on to several natural products, with good success. Not only did my cholesterol stay down but the high liver enzymes also dropped to the normal range and all this time I remained a daily user of comfrey. My hope is that there are more studies done on the whole plant so that we do not omit this valuable healer unnecessarily.
Thank you for taking the time to write regarding my news item on comfrey. The article was actually in reference to the Federal Trade Commission’s action taken against Christopher Enterprises, Inc. of Springville, Utah, regarding the agency’s position on the company’s comfrey product labeling. The information on PA toxicity related to comfrey was given for background information. I, too, would like to see positive controlled studies on the use of the whole herb. Unfortunately, until someone is willing to fund such studies, we won’t see them. I agree that comfrey is a useful herb, and have also commonly used comfrey salves and poultices since the mid-1970s. Your letter points out some common misconceptions with what has been reported on comfrey.
First, the human case reports in the scientific literature reporting toxicity from comfrey root and/or leaf ingestion (including one fatality) relate directly to use of whole herb preparations–not to the isolated PAs.
I do agree that it would be a tragedy to take this herb off the market. There is currently no restriction on the sale of comfrey products in any form on the American market. Where the regulatory agencies draw the line is in the labeling of such products. Knowledgeable comfrey users such as yourself can make their own decision on the risks versus the benefits of using comfrey in whatever form. That freedom to act does not extend to a freedom for product manufacturers to say whatever they wish on a label, however.
Also, in your letter, you offer proof based on your own experience of the safe use of comfrey based on monitoring of liver enzymes because of liver damage caused by a prescription medicine. The problem with the insidious nature of PA-toxicity from comfrey is that the diagnosis of the toxicity doesn’t show up in liver enzyme tests. It actually takes a tissue biopsy of the liver observed under a microscope by a trained diagnostician to detect veno-occlusive disease of the liver.
I, too, hope that more studies will be done, and will be delighted if the results of those studies are positive. However, if they are negative, I hope people will be open-minded enough to accept the results, even if contrary to their accepted beliefs. I was once a tried-and-true believer in the carte blanche use of comfrey. However, over the years, I have studied and analyzed the scientific literature on comfrey in enough depth to change my previous beliefs. I use comfrey salves on a regular basis, but I do not use comfrey internally. I do not intend to promote fear, but rather rational caution.
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