Comfrey, or Symphytum officinale Linn, has been cultivated since about 400 BC, as a healing herb. Ancient Greeks and Romans used comfrey to stop heavy bleeding, to treat bronchial problems, to heal wounds and for broken bones. Poultices were made for external wounds and tea was consumed for internal ailments.
Controversy about the safety of comfrey for internal use is still debating, even though comfrey based herb also offers therapeutic benefits. Comfrey can only be used externally as a medicinal herb for the content of allantoin. Several scientific studies reported that comfrey may be carcinogenic, since it appeared to cause liver damage.
The Scientific Studies
A 23 year old man with hepatic veno-occlusive disease and severe hypertension, died from liver failure. He was a vegetarian, and because of his illness, took comfrey leaves which are known to contain poisonous compounds called pyrrolizidine alkaloids. (Yeong ML, et al. 1990)
Comfrey leaves extracts 20% with dose 25 and 40 ml/kg bw (body weight) have an effect of lowering male mice's blood sugar levels, in which comparable to chlorpropamide (a drug that is used to treat type 2 diabetes mellitus) suspension of 22.5 mg/kg bw. (Amrizal M. 1998)
From above study by Indonesian scientist, Amrizal, many Indonesian herbalists also claim that comfrey, or kompri in Bahasa Indonesia, is useful to treat diabetes mellitus. But, it will need further scientific evidence to convince that comfrey based herb, is safe for internal use.
The present study identifies p-DGA (phytochemical poly (3-(3, 4-dihydroxyphenyl)glyceric acid)) from Caucasian species of comfrey (Symphytum caucasicum), as a potent agent against human prostate cancer (PCA) without any toxicity, and supports its clinical application. (Sangeeta S, et al. 2012)
Comfrey root extract is used to treat muscle and joint complaints. It is proven to relieve pain, inflammation, swelling of muscles, arthritis, acute myalgia in the back, sprains, contusions and strains after sports injuries, also in children aged 3 years and older. (Staiger C. et al. 2012)
External Use Only
In 2001, the US Food and Drug Administration banned comfrey based products which intended for internal use. Here are some comfrey based products for external use I found on Amazon.
|Burt's Bees Res-Q Ointment||Dr. Christophers Formulas Comfrey Ointment|
T.M. Teynor, D.H. Putnam, J.D. Doll, K.A. Kelling, E.A. Oelke, D.J. Undersander, and E.S. Oplinger. (1997)