Comfrey is the victim of a bad press, inaccurate reports, and four true cases of toxicity which in themselves are not straight forward, but suggest overdosing on comfrey. Governments in the UK and Australia have restricted the uses of comfrey root or banned the plant respectively.

The problem is two-fold: firstly there are two "comfreys" and reference to them is often casual. Regular, common, medicinal comfrey is Symphytum officinale. Russian comfrey, the great compost heap maker, is Symphytum x uplandicum. Medical herbalists in the UK, from whose written reports I am extrapolating, point out that Russian comfrey was probably the herb used in the toxicity trials, yet regular comfrey is also restricted or banned.

Secondly, when the toxicity tests were done in the late 70's, a chemical constituent called pyrrolizidine alkaloid was isolated, extracted from comfrey leaves and injected into baby rats at what many medical herbalists consider an "unrealistic level". In other words far more comfrey than a human would eat to get such a toxic level of PAs. Also baby rats are smaller than humans; they do not have the same metabolism as humans, and an isolated chemical injected outside the rat's stomach wall is not the same as a human eating leaves with many chemical constituents and digesting them normally. A chemical in isolation will cause different reactions from a group of chemical constituents containing that one as well.

To digress, but to explain I hope, Aspirin is a synthesized chemical, acetylsalicylic acid, based on a real life plant constituent found in Meadowsweet and Willow. Aspirin can cause ulcerations of the stomach lining. Meadowsweet has a soothing, gummy constituent called mucilage which lines the stomach, preventing erosion of the stomach wall but allowing the anti inflammatory properties of the salicylates of the herb to be utilized. OK?

So -- the bad guys in comfrey, the PAs were isolated and did bad things. But that too must be qualified.

The early research, late 70's, concluded that these PAs do indeed cause liver damage in humans. Medical herbalists would point out that Pyrrolizidine alkaloids can cause obstructions of the veins in the human liver, known as hepatic veno-occlusion, but were not shown to cause liver cell abnormalities and that the level of alkaloids in comfrey was too low to cause specific damage to liver circulation in any case.

And finally, is comfrey carcinogenic? The carcinogenic alkaloid has been identified as symphytine which apparently is about 5% of the total alkaloids in comfrey.

The original, often cited report was written by Culver et al in 1980. There have since been many criticisms of the research itself, how the scientific testing was conducted, which comfrey was really used, etc. What I found most interesting was the tumors in all but three of the rats were benign -- out of three groups of 19-28 rats and 3 groups of 15-24 rats. And the three malignant tumors were of low malignancy. There were clear cut cases of liver damage. That's in rats.

There are four cases involving humans which do implicate comfrey. One involved a woman who was finally diagnosed as having veno-occlusive disease and did consume a quart of herbal tea/per day that contained comfrey. A second case involved a boy with Crohns disease who was treated with conventional medicine for some time before going over to comfrey root & acupuncture. The long running malnutrition may have weaken the liver, predisposing it to the venal obstruction problem. Comfrey root was blamed. The drugs were not considered as possibilities. The third case involves a woman who overdosed! 10 cups of comfrey tea a day and handsful of comfrey pills. After 9 years, she had serious liver problems. The fourth case became a fatality. A vegetarian, given to specific food binges for weeks, took an unknown amount of comfrey for flu like symptoms possibly over a period of four months. The particulars of his case are blurred. All cases involve comfrey. In at least three, there are suggestions of overdose or abuse of the plant. WHICH plant, I don't know.

There are also disagreements about the efficacy and safety of leaves versus root. Some studies show the leaf to be almost alkaloid free -- thus safe. The UK finally restricted the internal use of comfrey root saying that there are still too many unanswered questions. Most medical herbalists I know will politely to vigorously disagree, but the law restricts the root. At least externally the root's OK here and the leaves can still be used as tea or poultice.

I'm sorry this is so long, but bear with me one more paragraph, please. I must credit Penelope Ode, MNIMH, former Editor, writing in Herbs, the British Herb Society magazine & Margaret Whitelegg, MNIMH, whose paper for the National Institute of Medical herbalists to the UK government in Defence of Comfrey was later published in the European Journal of Herbal Medicine. Both were published in 1993. I cannot do justice to their articles so briefly, but I do hope I have fairly summarized their writings. Any misstatements, confusion of explanations here are mine.

Rene Burrough rburrough@dial.pipex.com 

You might also think of using Symphytum, the homeopathic preparation of Comfrey, used for a long time for (and I quote from Murphy's Material Medica), Symph. is of great use in wounds penetrating to perineum and bones, and in non- union of fractures, irritable stump after amputation, irritable bone at the point of fracture, ...injuries to bones, cartilages, periosteum with excessive pain, or painful old injuries, pricking, stitching pains, remaining after wound is healed worse from touch. Deficient callous, affects spine, joint, knee. and also injuries to the eye are helped by this remedy. If this description fits the patient, 30c would be a good place to start, once per day.