Controversial Comfrey. Part 1

Monday, September 19, 2011 11:44
Posted in category Herbology

Used as a healing herb before 400 B.C., comfrey has long been regarded by herbalists as the ideal herb, so universally that of the hundreds of herbs used for healing, another name for comfrey is “healing herb.”

English herbalists consider comfrey to be the most powerful healing agent in the plant world, and 17th century herbalist, Nicholas Culpepper recommended comfrey roots “for all inward hurts and for outward wounds and sores in fleshy or sinewy parts of the body.”

Moved by the suffering caused by the Irish potato famine in the 1840′s, Englishman Henry Doubleday established a charitable association to research the cultivation and use of comfrey, with a vision of the world being saved from hunger by this herb.

A native of Europe and Asia, comfrey is said to have been brought to England by Crusaders returning from the Holy Land. The name comfrey is a corruption of the Latin con firmo, referring to the healing of broken bones. The botanical name, symphytum, is from the Greek symphyo, meaning “to unite,” but throughout the ages it was used to stop heavy bleeding and treat both bronchial and intestinal problems as well. It has many common English names including knitbone, knitback, boneheal, bruisewort, wallwort and consolida.

In magic rituals, comfrey was associated with money and protection from accidents and danger. Lore also says to place a leaf in one’s shoe to ensure a safe journey.

Comfrey belongs to the Borage family, Boraginaceae, which contains 20 different comfrey species and contains up to 4.7 percent allantoin, which promotes growth of new cells. It’s no surprise that comfrey has been used for centuries for its tissue regenerative abilities, as its mucilage soothes and softens skin, while allantoin speeds the healing of fractures by stimulating the formation of callus, the repair tissue that forms around a broken bone and joins it back together by bridging the gap. This explains one of comfrey’s old names, “wallwort,” from the Latin word wallen, to join or grow together.

Another important constituent of comfrey is cholin, known to be a powerful healing agent. Significant anti-inflammatory action is due to the presence of rosmarinic acid and other phenolic acids, and it seems to be effective in destroying harmful bacteria. High in calcium, potassium and phosphorus and many other useful trace minerals, comfrey’s green leaves are rich in Vitamins A and C.

Comfrey paste hardens like plaster, and cloths soaked in it were often wrapped around broken bones on ancient battlefields, making a primitive but effective cast. The juice of the crushed root, mixed with wine, was drunk to stop internal bleeding, particularly uterine hemorrhaging. The powdered root was snuffed up the nostrils to prevent or allay nosebleeds.

Historically, comfrey was used internally as well as externally, and proved especially valuable for gastrointestinal inflammations and ulcers. But comfrey now stands in the crossfire of opposing opinions. Is it an absolute must? Is it ideal for amateur herbalists? Is it perfectly safe and harmless? Or is it hazardous to the health?

In 1978, a study found that rats fed a diet containing comfrey leaves developed liver tumors, and recent studies indicate that comfrey might be carcinogenic. The root and young leaves contain pyrrolizidine alkaloids (PAs), which may cause liver damage if taken in large amounts. Research shows that, as isolated substances, PAs are highly toxic to the liver. It is still unclear whether they are toxic in the context of the whole plant, as they are only present in small amounts, often being completely absent from dried aerial parts. The highest concentration is in the root, and until its safety is confirmed or denied, the root should not be used internally.

Comfrey has been linked with hepatic veno-occlusive disease (HVOD) in which the liver’s blood vessels narrow and impair its function. In one case, a woman developed HVOD after taking six comfrey/pepsin digestive capsules daily and drinking a quart of comfrey tea per day. According to a report published in the New England Journal of Medicine, six comfrey/pepsin tablets could cause HVOD within a few months.

In another case, a boy with Crohn’s disease, a chronic intestinal disorder, took comfrey tea daily and developed HVOD in two years. Both of these cases involved unusually high doses of comfrey over unusually long periods of time. HVOD has never been reported in people taking the herb for brief periods. Experimental animals fed large amounts of comfrey for almost two years developed liver cancer according to the Journal of the National Cancer Institute, but comfrey has never been implicated in any case of human liver cancer, and the two cases of comfrey-induced HVOD do not constitute a major public-health threat. It has been suggested that other substances taken simultaneously by the two HVOD cases may have interacted adversely with the comfrey. The dried leaf contains no pyrrolizidine alkaloids and is considered relatively safe to use internally, and fresh, mature leaves contain very little pyrrolizidine. Comfrey also contains tumor-fighting substances, making it one of the many healing herbs that contain both pro- and anti-cancer chemicals.

In a landmark study published in Science Magazine, cancer authority Bruce Ames, Ph.D., chairman of the Biochemistry Department at UC Berkeley, estimated one cup of comfrey tea posed about the same cancer risk as one peanut butter sandwich (containing traces of the natural carcinogen aflatoxin), about 1/3 the risk of eating one raw mushroom (containing traces of the natural carcinogen hydrazine), about ? the risk of one diet soda (containing saccharin), and about 1/100 the risk of a standard beer or glass of wine (containing the natural carcinogen ethyl alcohol). He also said that comfrey/pepsin tablets carry up to 200 times the risk of comfrey tea.

Anyone with a history of liver disease, alcoholism or cancer should avoid the herb altogether. Until its safety can be established, avoid internal use and external use on broken skin to avoid possible absorption of toxic PAs. Don’t take while pregnant due to fetal hepatoxicity resulting from transferal of PAs from the mother. Take care with very deep wounds as the external application of comfrey can lead to tissue forming over the wound before it is healed deeper down, possibly leading to abscesses.

A final note to this controversy: University of Minnesota scientists report growing comfrey with no detectable PAs, so even those most violently opposing comfrey’s use may soon be able to give their blessings to new varieties of comfrey.

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