HERB - Re: Comfrey -- was chamomile

[Keith E. Brandt, M.D.]

>> If you are using Comfrey routinely, you should be aware that the FDA says
>> that long-term internal use has been found to cause liver cancer in rats.
>> 
>These findings are under debate.  Apparently, the cancer evidence was never
>actually found for COMFREY, just for some close relatives...therefore
>comfrey must also cause it, right?  But other studies have completely
>failed to find any carcinogenic effects of this plant.   (Information
>quoted from my recollection of entries in "The New Age Herbal" and a couple
>other sources I can't remember just now.  Sorry not to document... :-(...)

According to Tyler's "Honest Herbal", Comfrey *is* the culprit. 

"All comfrey species investigated have been found to contain hepatotoxic
pyrrolizidine alkaloids (PAs), but the literature on the subject is
confused due to a glaring lack of attention to proper botanical
identification of the various Symphytum species studied. Common comfrey
contains principally 7-acetylintermedine and 7-acetyllycopsamine in
addition to their unacetylated precursors and symphytine. It does not
contain high levels of echimidine, probably the most toxic comfrey PA.
Echimidine has been identified, along with symphytine and six other PAs, in
Russian comfrey. The former alkaloid is also present in prickly comfrey.
Comfrey root contains about ten times the concentration of PAs found in the
leaves." (page 98)

It continues to say that of 13 commercial common comfrey preparations
tested, 6 contained echimidine, and were therefore contaminated with other
species. Caveat emptor. 

Even the Germans (who use herbs extensively as first-line therapy have very
severe restrictions on the amount of comfrey ingested. (10 micrograms of
leaves, 1 microgram of root per day, no more than 6 weeks per year) (Honest
Herbal, page 99)

>On the other hand, we use comfrey because (among other things) it
>stimulates cell growth.  (knitting broken bones, etc.)  Cancer is --
>essentially -- uncontrolled cell growth.  So I can see how there might be a
>connection.

An old name for comfrey is knitbone, probably because it was used to treat
the pain and swelling of a fracture, not because it was thought to actually
heal the bone. (HH, p 97)

If you're worried about the effects of pesticide residuals, I think you
should be more worried about the carcinogenic potential of comfrey. My
opinion, YMMV.



 

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