Comfrey Cautions

   Cautions:

    "May cause liver damage if taken internally." L Ref. Fp.33

    "Not recommended for internal use except under careful supervision." L Ref F.p.33

    "Don�t use if pregnant." L Ref. Fp. 33

     " In 1968, Japanese scientists first reported the presence of pyroolizidine
   alkaloids in comfrey. Subsequent Australian research found these alkaloids in
   several plants of the Borage family and reported that rats red with up to 33% of
   comfrey leaf in their diet suffered liver cancer. But one of the few investigations
   using the whole plant has shown that it is not carcinogenic but the very opposite.
   Moreover, japanese doctors recommend a vinegar extract of the herb for
   cirrhosis of the liver. Several studies have found that comfrey can influence the
   sex hormones (note its steroidal saponin content) which stimulates the ovaries
   and testes. Ref. F p.33