Thursday, May 20, 2010

Comfrey - more details

This is an article I've had for several years, it is well worth the read for anyone interested in learning more about medicinal uses for plants.

For those not familiar with the author's by name, Rosemary Gladstar is a well known
Professional Herbalist and Author.

The Comfrey Controversy by Rosemary Gladstar

Over the past several years I've been increasingly aware of the controversy
surrounding the use of comfrey. At first, I simply ignored it, but recent
articles and current information have prompted me to write a response. I've
witnessed so much controversy over favorite herbs. Usually facts are
misleading and after several years of 'black listing' evidence creeps up
that redeems the deposed herb.

Sassafras, one of my favorite tea drinking herbs, was removed from the
market because of the potential toxic effects of the chemical safrole,
(though it's estimated that modern beer is 10 times more carcinogenic than
old fashion sassafras root beers banned by the FDA for the purported
carcinogen, safrole). After thirty years on the herbal black list,
sassafras is in favor again and is showing up in tea blends and formulas.
Pennyroyal has received deplorable press ever since two young women each
drank an ounce of the oil in the 70's and killed themselves. Cautious use
of licorice is recommended because of potential problems with elevated
blood pressure, though most studies indicate that licorice induced blood
pressure is due to concentrated licorice extracts, candy, and syrup, not
the whole root. Even slippery elm is listed as potentially toxic and is
not recommended for internal use. It seems that native women used the soft
inner bark of the elm tree vaginally to induce abortions. With all this
controversy it doesn't surprise me to see comfrey come to 'trial'. But
what does surprise me is the neurosis that herbalists are acquiring over
this comfrey cast. It's enough to give one an ulcer!

Are we getting lost in the backwash of current trends of herbalism that
Lean towards science, scientific testing, and professionalism? Are we
forgetting the value of centuries of recorded use? Is human testing
conducted over thousands of years no longer equal to laboratory scientific
testing? Shouldn't 'empirical evidence' at least be considered, and not
forgotten in the rush of scientific studies and latest 'findings'? Perhaps
it would be good to recall the rich historical documentation of comfrey,
which seems largely neglected in the rush to classify it as toxic.

Comfrey's been a favorite herb of most early herbalists and has been
written about for centuries in the famed old herbals. Hildegard of Bingen,
famous visionary, saint and herbalist of the Benedictines, recommended it
for wounds in the 11th century. Paracelsus, Pliny, Gerard, Dioscoriedes,
and Culpepper were all fans of the herb and recommended it highly. If
current information is correct, these famous healers were killing, not
healing, their patients.

It's no wonder comfrey's been extolled as one of the renowned healing Herbs
of all times. Its very name, Symphytum, means 'to heal'. Rich
concentrations of Allantoin. a cell proliferant that stimulates the growth
of connective tissue and cartilage make comfrey a specific for broken
bones, torn cartilage, swellings, and bruises. It contains tannin as well
as high concentrations of mucilage in its chemical make-up so is not only
soothing but constrictive and healing for wounds, cuts. and tears. It also
contains steroidal saponins making it particularly beneficial for
reproductive and hormonal imbalances. Along with all its specific healing
properties, comfrey is also a delicious and nourishing food herb. It:
contains high amounts of plant digestible calcium, iron. protein (up to
35%, seven times more protein than soybeans), B vitamins and vitamin A,
among other things.

Down through the ages in many parts of the world comfrey's been recognized
as one of the great healing herbs and has maintained its scrupulous
reputation....right up to the present day. In 1968 an independent Japanese
scientist first reported finding pyrrolizidine alkaloids, substances that
are regarded as potentially hepatoxic and carcinogenic, in the young leaves
and roots of comfrey. Austrian studies confirmed the Japanese reports. The
news spread through the scientific community and filtered into the herbal
community like wild fire. What a furor those reports caused. A recent
headline in one newspaper states "Warning! Comfrey Tea can Kill You!" Once
considered one of the great all time healing herbs, comfrey now sits on
trial as a possible carcinogen and as a cause of hepatic veno-occlusive

Pyrrolizidine alkaloids (PA's), a broad based chemical group including more
than 200 different alkaloids, are found in a widespread variety of
flowering plants throughout the world. They seem to be most concentrated
in members of the Borage family, the Pea family, and some members of the
Aster family. PA's first became a health concern in the mid 70's when,
during a severe drought several thousand Afghani villagers developed severe
liver impairment, many of whom died. The source of the problem was traced
to PA infected wheat (from a Heliotrope species).

There have been a couple of other epidemics of veno-occlusive disease
occurring in third world countries as a result of accidental and long term
ingestion of PA infected grain (traced to Crotalaria species). These cases
prompted an investigation of plants containing PA's. In the process,
comfrey, the most popular and widely used member of the Borage family, was
analyzed. It is difficult to draw any conclusive information, however,
from the tests given the various results reported. As is so often the case
with studies, there are enough discrepancies and various "scientific
findings" to satisfy what ever we'd like to believe.

Though it is important to be open to the possible dangers of comfrey, it Is
as important to sift through the information and misinformation and to form
opinions based on fact, rather than hysteria. The truth of the matter is
that most plants reveal within their chemical blue print a wide variety of
constituents, many of them potentially harmful. These chemicals form a
synergistic relationship with one another, often nullifying and or
strengthening certain aspects of one another. Michael Tierra states in The
Way of Herbs, "Plants have a dynamically complex biochemistry. In many
instances this allows for small amounts of substances, which when isolated
and concentrated might otherwise be poisonous, to be quite safe and
harmless." The sum total of these hundreds of chemicals determine the
personality, or action of the plant. Judging a plant's action based on one
chemical is like judging a person by the fact that their hair is brown.

Studies conducted in Washington found very minute amounts of Pyrrolizidine
alkaloids in comfrey. Some plants tested had none at all. An independent
researcher in the U.S. found that of three samples tested for pyrrolizidine
alkaloids, one was negative, the second contained only trace amounts, and
the third contained one part per million equaling a sum total of an
infinitesimal amount of this alleged toxic substance. In Steven Foster's
article in the February issue of Herb Companion he cites that 8 PA's have
been identified, though different varieties of Comfrey have various amounts
and only two of the most abundant PA's, according to him, are under
scrutiny. It brings to mind the words of the highly respected Dr. Rudolp
Weiss "Modern methods of chemical analysis are now so sophisticated,
working in nano units (l0 to the 9th power), that harmful substances will
be found almost anywhere, with the result that we feel constantly
threatened." Dr. Weiss, by the way, seemed cautious about accepting
current research on comfrey toxicity.

It might be discerning while reviewing the PA containing factor of Comfrey
to consider the rest of this plant's biochemical characteristics. Comfrey
is rich in allantoin, a cell proliferant, calcium salts, and
mucopolysaccharides, all of which are very nutritious to the cell and may
serve to neutralize the cell inhibiting action of the pyrrolizidine
alkaloids. It is also important to note that the pyrrolizidine alkaloids
found in comfrey are in a "N-oxide", or organic state, unlike those used in
laboratory studies. These organic compounds are more likely to be degraded
when digested in the human body.

Another important issue to consider is the nature of the tests used to
determine the toxicity factor of comfrey. Once identified, the alkaloids
were isolated and injected into laboratory animals in rather massive
amounts, far more than would normally be ingested. Richard De Sylva states
in The Canadian Journal of Herbalism: "The original research (on the
presence of pyrrolizidine alkaloids in comfrey) was seriously flawed. The
laboratory rats that developed tumors on the liver were only six weeks old.
At this age, quite a number of substances would be inappropriate for them
to ingest. As well, the total amount of comfrey ingested formed 30-50% of
their basic diet. This could be compared to human consumption of several
platefuls of comfrey daily. This daily regimen did eventually cause tumors
to grow on their livers and proved only one of the standing laws of
science: that every substance or chemical is a poison if we consume enough
of it." Or as Paracelsus said several hundred years ago, "All things are
poison and nothing is without poison. It is the dosage that makes a thing
poisonous or not." It might be wise to note when observing animal studies
that comfrey is used extensively as a fodder for dairy and beef cattle
throughout the Pacific Northwest with no problems. In fact, farmers are
growing fields of comfrey because of the outstanding results in milk
production and the health of the herds.

Because of these laboratory findings, an attempt was made to collect Case
histories of individuals who used comfrey and later developed liver
toxicity. However, of the thousands of people who use comfrey worldwide,
only three somewhat questionable cases have been identified, none of which
conclusively point to comfrey as the culprit. In 1984 there was a case of
veno-occlusive liver disease in a 49 year old woman who had been taking
Comfrey- Pepsin tablets for four months. The American Journal of Medicine
reported a case of a woman who reportedly drank as many as I0 cups of
Comfrey tea a day and handfuls of tablets and developed veno-occlusive
liver disease. The third reported case of veno-occlusive liver disease was
that of a 23 year old New Zealand man who died of liver failure reportedly
due to veno-occlusive liver disease. He was said to have eaten four or
five steamed comfrey leaves every day for one to two weeks before he died.

This appears to constitute the complete 'hard evidence' for condemning
comfrey. Not having access to the complete case histories on these
patients I can make no statement of whether, in fact, comfrey is the only
possible etiologic factor for the liver pathology. Even if it is, three
cases out of tens of thousands, perhaps millions of people who use comfrey
is not statistically significant enough to ban its use. If our
pharmaceutical industry were subject to such standards, we would have no
drugs on the market at all. And very few herbs.

No matter what your position on this matter, this toxicity information
should be put in perspective. Mark Blumenthal states, "The comfrey
incident might have looked different if it I had been put into context of a
toxicity scale. One such scale is the HERP index, which classifies the
cancer-causing potentials of various substances. Extrapolating from the
HERP index, former U.S. Department of Agriculture botanist James Duke,
Ph.D., calculates that less than one-fifth an ounce of brown mustard is
twice as cancer causing as comfrey tea, which has roughly the same
cancer-causing potential as a peanut butter sandwich. Wine is 144 times
more cancer causing than an equal amount of comfrey tea."

It is essential to always recall when reading test results that the Whole
is always greater than the sum of the parts. As more and more tests are
being conducted on herbs and the chemicals isolated, it is important to be
open minded about the results; open minded to the fact that science is
fallible. If a plant has been found safe and effective for a thousand years
of human use, it may be wise to question the validity and applicability of
the tests being used. There is generally some unidentified part of the
plant in the form of another chemical or an innate natural wisdom that
allows the medicine, when taken as a whole, to function in a safe and
beneficial manner.

The comfrey controversy continues to rage. Banned in Canada, comfrey
Awaits its fate in the U.S. Some herbalists continue to use comfrey basing
their faith on 'the empirical evidence of the ages' and ignoring current
data. Most herbalists are taking a more conservative discerning stand
Recommending small amounts of comfrey for internal purposes (awaiting
pending information) and continuing to use it externally. Some herbalists,
caught up in the ferver of the tests, have discontinued its use altogether
and advocate others do so also. As for me, until the evidence and 'hard
facts' are much more compelling, I will continue to use comfrey judiciously
for myself and my clients. Meanwhile, the Austrian company that conducted
the original tests verified that the tests were inconclusive and in Japan,
where the alkaloids were first discovered, doctors still continue to
recommend comfrey for cirrhosis of the liver.

Through its whole "trial" comfrey seems unabashed. It continues to
dauntlessly grow. A large luxurious plant, its carefree attitude seems to
say, "if you doubt my safety, don't use me! I've been around a long long
time. I'll outlast the controversy."

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