Shark Cartilage:
The Myths and Possible Truths of its Health Benefits
by www.SixWise.com
Scientists have been studying shark cartilage as a potential
treatment for cancer for decades, based on the fact that sharks
do not appear to get cancer as often as humans.
Scientists suggest that shark cartilage contains compounds
that may fight cancer -- but it may not be effective
in the powdered form sold over-the-counter.
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"Scientists have believed for over 35 years that since
sharks do not appear to develop as much cancer as humans,
there may be something in their systems that protects them
from getting cancer," said Gabriel Feldman, MD, director
of prostate and colorectal cancer for the American Cancer
Society.
The most popular theory behind the idea that shark cartilage
may cure cancer has to do with the composition of the cartilage
itself. Cartilage does not contain blood vessels, which makes
it difficult for cancer to grow in it.
It's thought that cartilage actually makes substances that
block the growth of new blood vessels (angiogenesis) that
would feed a tumor. Therefore, using cartilage to treat a
tumor may keep blood vessels from forming in it, and cause
the tumor to stop growing or shrink.
As news of this "breakthrough" cancer treatment
hit the media, its popularity soared, and surveys from the
late 1990s showed that over 25 percent of patients with varying
illnesses used shark cartilage supplements as complementary
or alternative medicine.
However, the debate is still going strong as to whether or
not shark cartilage is beneficial or just a marketing gimmick.
Is Shark Cartilage a "Triumph of Marketing and Pseudoscience"?
According to Gary K. Ostrander, a research professor in the
departments of Biology and Comparative Medicine at The Johns
Hopkins University, the use of shark cartilage as a cancer
treatment has had dangerous effects on both humans and sharks.
"Since shark cartilage has been promoted as a cancer
cure, not only has there has been a measurable decline in
shark populations, but cancer patients also have been diverted
from proven, effective treatments," he says. "People
read on the Internet or hear on television that taking crude
shark cartilage extract can cure them of cancer, and they
believe it without demanding to see the science behind the
claims."
Out of the many studies that have examined shark cartilage
as a cancer treatment, some have, in fact, found no benefit,
including a 1998 study by the Cancer Treatment Research Foundation
that found "shark cartilage powder has no effect on slowing
the cancer, improving the quality of the participants' lives,
or shrinking the tumors" of 60 advanced stage cancer
patients.
Other laboratory studies on animals have found no effect
from shark cartilage, while still others have found the substance
to be beneficial in slowing the growth and spread of cancer
cells.
The Form of the Shark Cartilage May Make a Difference
Although the Food and Drug Administration has found no conclusive
evidence that shark cartilage is beneficial as a cancer treatment,
clinical trials are underway using substances that are isolated
from shark cartilage.
Shark populations have declined significantly in the
last decade due to an increased demand for shark cartilage
and other shark products.
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"The fact is that it is possible that highly purified
components of cartilage, including from sharks, may hold some
benefit for treatment of human cancers," Ostrander said.
"The key will be to isolate these compounds and design
a way to deliver them to the site of the tumor."
It turns out that powdered shark cartilage and substances
isolated from shark cartilage may have very different effects.
Shark cartilage itself, scientists say, contains molecules
of the active ingredient that are too large to be absorbed
into the bloodstream when they're taken by mouth. Instead
of being beneficial, the cartilage passes through the body
without breaking down or being used.
"Everybody in [the field of oncology] knew way before
this article was published that shark cartilage cannot possibly
be beneficial," said Barrie Cassileth, PhD, author of
The Alternative Medicine Handbook, referring to the 1998 study.
However, "there are possibly chemical components in
shark cartilage that may have a tumor-reducing effect,"
he said.
As it stands, shark cartilage that's available over-the-counter
has gotten mixed reviews. Studies vary on whether it provides
benefits or not, it can be outrageously expensive, and environmentalists
point out that global shark populations have declined significantly
in the last 15 years due to over-fishing and an increased
demand for shark products.
Meanwhile, isolated shark cartilage components may one day
hold promise of benefiting cancer patients. These compounds
-- being developed and tested by several pharmaceutical companies
-- would likely only be available by prescription, and reportedly
come from sharks that have already been slaughtered for meat
(or one day might be made synthetically).
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Sources
National
Cancer Institute
American
Cancer Society
National
Cancer Institute: Cartilage
Science
Daily