Papaya - a world class meat tenderizer, natural digestive aid, prevents ulcers, and also a soft contact lense cleaner.Comfrey The Safety Factor
Comfrey has been found to contain chemicals (pyrrolizidines) that in large amounts cause serious liver damage and cancer in laboratory animals. As a result, Canada banned comfrey (and coltsfoot), and herb critics are pressing for similar bans in the United States.
The liver Scare
Comfrey has also been known to cause liver damage in humans. Excessive amounts of the herb can cause a disorder known as hepatic veno-occlusive disease (HVODJ, or Budd-Chiari syndrome, in which the liver’s blood vessels narrow, impairing its function.
In one case, a woman developed HVOD after four months of taking six comfrey/pepsin digestive capsules daily and drinking a quart of comfrey tea a day. According to a published report in the New England Journal of Medicine, six comfrey/pepsin tablets a day could cause HVOD within a few months.
In another case, the parents of a boy with Crohn’s disease, a chronic intestinal disorder similar to ulcerative colitis, took him off standard treatment and gave him comfrey tea instead. After two years, he developed HVOD.
Both of these cases involved unusually high doses of comfrey for unusually long periods. HVOD has never been reported in people taking recommended amounts of the herb for brief periods.
The Cancer Question
Experimental animals fed large amounts of comfrey for almost two years developed liver cancer, according to the Journal of the National Cancer Institute. Roots caused more cancer in the animals than did leaves.
Comfrey also contains tumor-fighting substances, making it one of many healing herbs that contain both pro- and anticancer chemicals. Comfrey contains appreciable amounts of antioxidant nutrients-vitamins C and E and beta-carotene, which the body converts to vitamin A. The American Cancer Society recommends a diet high in antioxidant nutrients to help prevent cancer.
Safety Issue Unresolved
Today, authorities are divided on comfrey’s safety for internal use. Critics continue to villify the herb. A study published in the Lancet estimated a single cup of comfrey root tea might constitute a “significant health risk.”
But Britain’s National Institute of Medical Herbalists says, “No man, woman, or child has been recorded as suffering toxic effects from taking I recommended doses! of comfrey leaf or root as medicine.”
In a landmark study published in Science, cancer authority Bruce Ames, Ph.D., chairman of the Biochemistry Department at the University of California at Berkeley, attempted to estimate the average person’s lifetime cancer risk from exposure to hundreds of man-made and naturally occuring carcinogens. He estimated one cup of comfrey tea posed:
- About the same cancer risk as one peanut butter sandwich, which contains traces of the natural carcinogen aflatoxin.
- About one-third the risk of eating one raw mushroom, which contains traces of the natural carcinogen hydrazine.
- About half the risk of one diet soda containing saccharin.
- And about one-hundredth the risk of a standard beer or glass of wine, which contains the natural carcinogen ethyl alcohol.
Dr. Ames also estimated that comfrey/pepsin tablets carry up to 200 times the risk of comfrey tea.
The lesson is clear: Don’t use comfrey/pepsin tablets. Many other herbs aid digestion without any risk of liver damage.
Anyone with a history of liver disease, alcoholism, or cancer should steer clear of the herb altogether. But Dr. Ames’s work strongly suggests that for the occasional user, comfrey’s hazards have been blown out of proportion. 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.
A Safe Path
The Food and Drug Administration lists comfrey as an herb of “undefined safety.” For otherwise healthy non-pregnant, non-nursing adults who are not taking other medications and have no history of liver disease, alcoholism, or cancer, comfrey may be considered relatively safe for short-term occasional use in amounts typically recommended.
Comfrey should be used in medicinal amounts only in consultation with your doctor. If comfrey causes minor discomforts, such as stomach upset or diarrhea, use less or stop using it. Let your doctor know if you experience any unpleasant effects or if the symptoms for which the herb is being used do not improve significantly in two weeks.
Easy to Grow
Comfrey is a hardy 5-foot perennial with large, hairy, lanceshaped leaves, thick, spreading roots, a hollow, bristly stem, and bell-like flowers, which may be white, blue, or purple.
Comfrey can be started from seeds, but it grows best from root cuttings taken in spring or fall. An inch-long piece of root planted in 3 inches of soil almost always produces a plant. Set cuttings 3 feet apart. The herb grows in any well-drained soil and tolerates full sun or partial shade.
Comfrey spreads vigorously. Contain it in a pot, or border it with sheet metal to a depth of 12 inches.
Leaves may be harvested when the flowers begin to bud.
Gather the roots in autumn, after the first frost, or in spring before the first leaves appear. Wash harvested roots thoroughly and cut them into slices to dry. Then powder them in a blender or coffee grinder. Store in a sealed container.
Just as necessity is the mother of invention, safety scares are often the mother of hybridization. University of Minnesota scientists report growing comfrey with no detectable pyrrolizidines. Even the herb’s harshest critics may soon be able to give their blessings to new varieties of the herb.