Monday, July 30, 2012

The Comfrey Controversy

Comfrey root and leaves (Symphytum officinale) has been an herb used for most of human history. Nicknamed "knitbone" and "boneset," this sweet, cool and moist herb, yielding from damp places in Europe, has long been used in the repair of damaged tissues. Its large oblong leaves have a hairy quality to them and when cultivate here in the US, it has the tenaciousness to take over your garden.

Comfrey: The Wound Healer
Comfrey is, in my opinion, the best herb for repairing broken bones and treating strains, torn ligaments, bruises and joint issues. Internally and externally it is amazing at promoting the healing process of tissue, bones and muscles and also helping to mediate proper scar formation. Allantoin, one of its constituents, is said to be responsible, at least partly, for its wound healing properties by stimulating cell proliferation, increasing the body's immune system and decreasing inflammation. Comfrey is so amazing at wound healing that if it is used topically on deep wounds, there is a chance that the surface tissue can heal, sealing in infection and creating a possible abscess.

Other Uses
Comfrey is also helpful for ulcers and ulcerative colitis. It contains mucilage that soothes ulcers and the wound healing properties help to heal them. Other uses of comfrey include being an expectorant for bronchitis, dry coughs and TB and its tannins make it an astringent, helping to control hemorrhaging.

Comfrey Has Been Bastardized!
Comfrey has been used for hundreds of years; however, over the last 30 years its credibility and reputation have been tarnished due to the presence of pyrrolized alkaloids (PA's) in this plant. PA's have been shown to cause hepatic toxicity, particularly hepatic veno-occclusive disease, which is when the small and medium sized veins in the liver become blocked. Comfrey root contains more PA's than the leaves, and the young leaves contain a higher concentration than the mature leaves. S. officinale has the lowest PA concentration of the comfrey species.

The Lowdown on Pyrrolized Alkaloids
Most of the human data on PA toxicity comes from cases of consuming plants high in PA's other than comfrey. In the 1980's and 90's several cases of hepatic toxicity from comfrey were reported and several people died. But these reports of toxicity did not take into account other factors such as other underlying illnesses that may be responsible, the use of hepatotoxic over the counter drugs or the nutritional state of the individuals. Most of the other research done with comfrey is done on rats and as David Hoffmann points out, Rode gives us 4 limitations of the research done so far with comfrey:
  1. Not all PA's have the same toxicity and the ones in comfrey are far less toxic than in other plants, which can cause serious human toxicity. Is it acceptable to generalize the toxic nature of some PA's to all PA's?
  2. Not all animals have the same reaction to PA's. For example, pigs are easily poisoned by the PA's present in other plants, but they can eat large quantities of comfrey as food and show no toxicity. If rats were to consume the same percentage of comfrey (based on the weight of animal), they show significant toxicity. Are rats acceptable models for the human consumption of PA's, particularly the ones found in comfrey?
  3. Comfrey species vary in PA content. S. officinal contains less toxic PA's than Russian comfrey (Symphytum x uplandicum). If research is conducted using Russian comfrey than the results are not reliable and should not be generalized to all forms of comfrey.
  4. Studies of isolated PA's and extracts are not representative of the whole plant. The whole is greater than the sum of its parts. One example of this is white willow bark. This plant contains salicylic acid, commonly known as aspirin. Aspirin is known to cause ulcers. Even though white willow bark contains salicylic acid, it does not cause ulcers; in fact, it can be used to help treat them. This is because white willow bark also contains other constituents that buffer the effects of the salicylic acid. So even if the PA's in comfrey, when isolated, cause toxicity, there might be another ingredient in the plant that helps to buffer this toxicity.

Overall, these safety assumptions are based on inadequate data and as a result, comfrey has been banned in Australia, restricted in New Zealand and the UK offers no oral medications that contain comfrey. In the US, the FDA has banned comfrey for internal use and even question its safety topically (there is only a very small amount of PA's that are absorbed through the skin). So the FDA has banned the internal consumption of comfrey which may be linked to two deaths and may show some liver toxicity (which is not well demonstrated); however, the FDA ignores the thousands of deaths every year that is caused by pharmaceuticals. Prescription narcotic drug overdoses now claim 1 life every 14 minutes in the United States and as for the people who took exactly what was prescribed to them in exactly the correct dose, they account for 100,000 deaths a year. Why aren't theses FDA approved pharmaceuticals banned for internal consumption?

Even though there needs to be more research and human studies done to prove or disprove safety concerns regarding comfrey, I DO NOT recommend using comfrey internally for anyone. I, personally, take comfrey internally for short periods of time for certain issues because I feel that the therapeutic advantages outweigh the risk involved. For legal purposes, I am sad to say that not until comfrey is shown to be safe within the medical community and the FDA will I be able to recommend it to others for internal use.


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to the best herbs for healing. Emmaus, Pa: Rodale Reach.

Gladstar, R. (2001). Rosemary Gladstar's family herbal: a guide to living life with
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Hoffmann, D. (2003). Medical herbalism: the science and practice of herbal medicine.
Rochester, Vt.: Healing Arts Press.

Levy, J. d. (1997). Common herbs for natural health (Rev., expanded ed.). Woodstock,
N.Y.: Ash Tree Pub..

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