Talk to me about Comfrey

cmfarm":3m43s3lv said:

After reading the article posted it sounds like it is not recommended to feed to animals due to liver issues.

"SPECIAL NOTE: This article was originally published as "Comfrey for the Homestead" in the May/June 1974 issue of MOTHER EARTH NEWS. At that time, comfrey had not yet been declared potentially poisonous to humans and animals and this article contained information about using comfrey as a vegetable, in tea and as livestock fodder; none of these applications are advisable, according to FDA and FTC recommendations. Comfrey contains at least 8 pyrrolizidine alkaloids, which can build up in the liver to cause permanent damage and sometimes death. Because of this, comfrey preparations are not sold for oral or internal use in the United States, the United Kingdom, Australia, Canada or Germany. "

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ottersatin":13wc5dtc said:

Those of you who grow/feed it; what is your actual experience with it?
Hello alforddm,
I have been feeding Comfrey to my Herd for many years.
I have never seen any problems with it's use.
I however feed it only as a treat, not as a basis of the feed regimen.
The Rabbits seem to love it, when I walk into the rabbitry they run to their cage doors for the thing! I learned of Comfrey from those who came before me, with each item we choose
to feed as in medicine, there comes a search for truth in it's use and benefit.
I feel that the members of my herd have and continue to reap a benefit
from my use of Comfrey. Should things change abruptly within a short time
perhaps I may rethink my use of this what appears to be beneficial plant.
For now I continue to do as I have. We all must decide for ourselves,
what is best for those in our charge.
Ottersatin. ldtimer:

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Rainey":3rzu8za0 said:

We've fed comfrey to goats, rabbits and pigs. Some are more willing to eat it than others. Some will eat it after it has wilted some. It seems to be preferred in its early growth stage, before flowering. We've tried drying it but the result wasn't satisfactory--no one would eat it. I think the hens have also eaten it fresh and plan to try feeding it to them again this season.
I've seen the toxicity studies but also others refuting them. It is also nutrient rich.
We use it in compost and mulch because of the nutrients and in hilling potatoes to help prevent scab.

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carry out the ideal programme of processing all the samples simultaneously. This is possibly of even greater significance thanfirst realized as the alkaloid proved to be unstable and was very easily oxidized and destroyed during extraction. However itcan be seen that with one sample of comfrey tea a Tertiary alkaloid content of ·010 per cent and a total alkaloid content of ·030 per cent was obtained which agreed with that obtained at Exeter University and the Toxicology Unit, whereas withanother sample of comfrey tea the values were ·004 per cent and ·009 per cent respectively. At least part of this differencemay be due to differences in the plant material used for the different tea samples and the conditions for drying the leaves.Comfrey tea naturally is of considerable interest in this study due to the quantities consumed for medicinal purposes bymankind and further observations will be made on this later in the report. It should be noted that mean values are given for two or more different sets of samples taken at different times in the period Sept.-Nov. Although variations were observed between samples, no seasonal trend could be detected.For tertiary alkaloids it is interesting to note that the lowest concentration was observed in Bocking Clone No. 19, whereasabout six times this concentration was observed in the wild stock S. asperum
and this was also reflected in the total pyrrolizidine alkaloid content. In general the tertiary alkaloids constituted about 50 per cent of the total value.The variations observed in the analytical values indicated that much larger numbers of samples and uniform conditionswere required for a comparison of the results to be statistically significant but unfortunately this could not be financiallyustified at this stage. A larger number of chromatographs was also needed for the determination of the R F values usingT.L.C. The method used is very effective in separating out closely related alkaloid compounds but unfortunately is lessreliable in giving repetitively reproduceable results. In Table 1 values are given for the main spot on the plate with a secondfainter spot following fairly closely behind it. Much more work needs to be done to sort out and identify thesechromatographic spots but this was considered to be beyond the scope of this study. However it can be seen that with the possible exception of S. asperum, the alkaloids behaved quite differently from the monocrotaline standard alkaloid havinghigher R F values. In their paper (1) on S. officinale Furuya and Araki detected symphytine and echimidine both of whichthey showed to be diesters having the typical nitrogenous pyrrolizidine nucleus and they found that echimidine had a lower R F
value. Thus the spots observed by us are most probably those of symphytine and echimidine or their closely relatedcompounds. For their research the Japanese workers confined themselves to S. asperum only and used 5Kg (11 lb.) of rootmaterial which contained 0·226 per cent of the crude alkaloid, a massive quantity compared with the 50 gm (1·8 oz.) of driedleaf containing ·030 per cent used by us. However, our results suggest that minor differences in the alkaloid structure maywell exist between the clones. Such differences could be important in terms of the stability of the alkaloids and also their toxicity.In their paper, Furuya and Araki (1) also report on a pharmacological test with rats showing symphytine to have an LD 50 of about 300 mg/Kg; that is an intravenous injection of 300 mg of the purified alkaloid per Kg of rat tissue caused death inapproximately 50 per cent of the experimental animals. Similar experiments with alkaloid extracted from the roots of theBocking clone No. 14 failed to demonstrate a similar toxicity at this level which may reflect slight differences in structure towhich reference was previously made. For many purposes toxicity in rats is equivalent to that in mankind so that these resultsafford definite indication of the level of possible danger comfrey may be in human consumption. Thus in the case of comfreytea if it be assumed that normal methods of infusion could extract just over half the alkaloid that was extracted by 8 hours in aSoxhlet apparatus in the laboratory, each cup of tea could contain 100 micrograms of alkaloid. At this level the consumer could never attain the lethal dose of 300 milligms/Kg tissue found necessary to produce the acute reaction in rats. Even toconsume this quantity it would take a 150 lb. man drinking 4 cups of tea per day a total of 140 years. Furthermore it is knownthat to produce chronic reactions sub-lethal doses over a prolonged period are necessary. Normally such sub-lethal doseswould need to be of a much higher order particularly as sensitivity to the alkaloid decreases with age.Rats fed on a diet containing a high proportion of comfrey flour over a long period were examined after death anatomically, biochemically and histologically for symptoms of a chronic reaction of the liver to the alkaloid. Typically there is a colour reaction in the liver tissue itself, followed by the appearance of tumour cells and ultimately large visible protruding tumours. None of these symptoms were found in the experimental rats. As has been stated the alkaloid proved to be an unstablecompound and was easily oxidized and it would appear conceivable that apart from its low toxivity in the purified state aconsiderable portion of the alkaloid would be destroyed in preparation and cooking of the comfrey flour. With fresh herbagesuch as leaves in salads it is possible to eat only a relatively small quantity and with its high water content the amount oalkaloid thus actually eaten by man would be very small and there would naturally be present in such herbage catalyticenzymes which would hasten its destruction. Livestock which may consume larger amounts of herbage frequently only eat itwhen wilted, and thus at a time when enzymatic breakdown could well have begun. Certainly prolonged and extensive use ocomfrey herbage as a feeding stuff for animals has failed to reveal any deleterious effects, but rather that of considerable benefit to the health of the livestock. Furthermore it must also be remembered that many other species of plant considered safe for foodstuffs actually contain toxic alkaloids but in amounts too small to be harmful.

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The very few specific reports of human toxicity related to comfrey all come from the period between 1980 and 1990, when a number of cases of veno-occiusive disease were reported.[9] There is no question about the diagnoses. However, it is important to note that in these cases, the connection with comfrey was not considered in the context of other contributing factors. For example, concomitant illness, the use of prescription or over- the-counter hepatotoxic drugs (like acetaminophen, for example), and impaired nutritional status clearly increase the likelihood that PA-containing herbs will cause hepatotoxicity.

With minimal epidemiological data, what insights can be garnered from the laboratory research into toxicity? As with many statements about herbal toxicity, the evidence proffered comes primarily from rodent studies that utilized high levels of purified PAs. No systematic toxicity testing or clinical trials of comfrey have been performed. Although PA poisoning in humans does occur, it is most commonly a consequence of consuming plants other than comfrey.[10]

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Rainey":1893m4hr said:

It is so hard to tell what is true or not about food/herbs and such. It seems that one doctor will say one thing and then another will say something different. Or things will change from one month to another. I wish it was easier to find true real info about such things.

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I neglected to say in my earlier post in this thread that we feed comfrey, not as a treat nor as herbal treatment, but as part of the mix of forage that we feed instead of pellets. As with anything else, I would not feed comfrey exclusively. Have no study to lend authority but it is my understanding that variety is important to providing a balance when relying on natural feed instead of pellets.
The other thing, which you probably already know, is to put your comfrey where you don't mind it spreading, not where you have something you cherish but which has trouble competing. In our view, extra comfrey is a good thing, because of its uses in the garden as well as feed. But there are places we don't want it and it can be hard to remove--any root bits mean more plants.

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My rabbits love it, and either my rabbits do not become sick from it, or else it isn't being taken in high enough levels to cause problems. The question is: If pyrrolizidine alkaloids build up in the liver...would we be exposed to them them if we ate the liver?

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Rabbits
Rabbits are relatively insensitive to PA toxicosis following the ingestion of contaminated feeds
(Pierson et al., 1977; Swick et al., 1982). For example, when rabbits were given a total dose of
Senecio jacobaea representing more that 12.5 % of their initial body weight over a period of 263
The EFSA Journal (2007) 447, 1 - 50
http://www.efsa.europa.eu Page 22 of 51
days, no obvious clinical signs or significant gross lesions in livers could be observed.
Histological examination showed, however, typical PA associated lesions. After injection of PAs
rabbits do show clear signs of PA toxicity, but an intraperitoneal injection of a dose of 150 mg/kg
body weight (total PAs, not specified) caused death within 24 hours (Pierson et al., 1977).

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Significant differences in the species-specific sensitivity to PAs have been noted, which
correlate with the expression of biotransformation enzymes involved in the metabolic
conversion of individual PAs. It is generally recognized that rodents, as well as pigs, poultry,
cattle and horses are very sensitive to PA intoxication, whilst sheep, goats and rabbits are not.

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Comfrey is an herbal medicine with a history of effective therapeutic use in humans. It has documented anti-inflammatory and wound-healing properties and many holistic healthcare providers view comfrey as a crucial element in their repertoire of herbal therapies for treating injury and disease in humans. However, because PAs are an intrinsic component of comfrey, its therapeutic use might increase the risk of liver toxicity. Clearly, the risk of hepatic damage during treatment with comfrey will be influenced by its source, the amount consumed, the duration of treatment, and the health and nutritional status of the patient. However, the information currently available is not sufficient to permit an accurate assessment of the risks or potential therapeutic benefits of comfrey. A more precise and credible measure of health benefits would ensure appropriate use by herbalists and medical practitioners.

Research to date has often been flawed by the use of inappropriate animal models and faulty experimental design. Correct botanical identification and analysis of the plant material for PA content and profile is essential. In addition, animal species vary widely in their susceptibility to PA toxicity, and the toxic response is dependent on the specific PA. Therefore, it seems imperative that toxicity testing be conducted in several animal species.

Perhaps the most direct approach to assessing the benefits and attendant risks of the therapeutic use of comfrey would be to screen the current population of comfrey users. A direct determination of risk would offer the greatest protection to individuals currently consuming comfrey, and provide the information required for placebo-controlled prospective clinical studies designed to determine efficacy and define safe use.

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Conclusions
Individual clinical trials showed evidence of benefit for ankle distortion, back pain, abrasion wounds and osteoarthritis. Topical application appears to be safe but further rigorous assessment is needed. Systematic reviews focussing on particular indications may clarify the treatment effect and safety of external comfrey preparations.

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Rainey":1rasy1n7 said:

I neglected to say in my earlier post in this thread that we feed comfrey, not as a treat nor as herbal treatment, but as part of the mix of forage that we feed instead of pellets. As with anything else, I would not feed comfrey exclusively. Have no study to lend authority but it is my understanding that variety is important to providing a balance when relying on natural feed instead of pellets.
The other thing, which you probably already know, is to put your comfrey where you don't mind it spreading, not where you have something you cherish but which has trouble competing. In our view, extra comfrey is a good thing, because of its uses in the garden as well as feed. But there are places we don't want it and it can be hard to remove--any root bits mean more plants.

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the reluctant farmer":1rasy1n7 said:

In the area I grew up in it was regularly used by the Polish & Russian immigrants who had migrated there, and it rapidly spread from small homesteads to becoming invasive with the use of industrial tilling methods. My understanding was that it was used by the old settlers as a medicine by poultice or through tea/tonic and also as an animal food. I'd suspect that either the toxicity reports come from large amounts or if it is eaten in isolation. Possibly they were eating other things alongside it that balanced out any accumulation. I think Rainey's approach makes sense, and I intend to be feeding it this year since I have some plants my mom dug up and gifted me with. Will check out how my meat mutts do with it...

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michaels4gardens":1333dy4r said:

I have done some research on feeding comfrey, -when more then 35% of the diet was comfrey, I began to see lighter spots on the livers, and slight yellowing of the liver,[at 8 week butchering] and the growing rabbits slowed down on growth rate. I fed 25% as a part of the ration for 3 years, and saw a good increase in growth rate over the litters that did not get it. I saw no problems with the breed stock at all [but did not kill any of them to look] the greatest advantage was when the kits were still nursing, --it seems to me- does produce more milk when fed comfrey.

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alforddm":36gun4bz said:

michaels4gardens":36gun4bz said:

I have done some research on feeding comfrey, -when more then 35% of the diet was comfrey, I began to see lighter spots on the livers, and slight yellowing of the liver,[at 8 week butchering] and the growing rabbits slowed down on growth rate. I fed 25% as a part of the ration for 3 years, and saw a good increase in growth rate over the litters that did not get it. I saw no problems with the breed stock at all [but did not kill any of them to look] the greatest advantage was when the kits were still nursing, --it seems to me- does produce more milk when fed comfrey.

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Do you still feed comfrey? So, according to your observations an amount up to 25% of the diet can be beneficial?

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