Note from Ilena Rosenthal:
I see the Quackwatch / Healthfrauds campaginers are gving the non
skeptical viewpoint of Vitamin C ... I find their closed minded
bigotry alarming on the subjects they have drawn premature and pharma
favored conclusions on ...
Barrett, himself not even board certified,annointed double Nobel
Peace Prize Winner as one of his many, many targets on his attack
websites (quackwatch / nchaf.org etc.) on this very topic.
www.BreastImplantAwareness.org/QuackWatchWatch.htm
How Vitamin C Stops Cancer
http://www.sciencedaily.com/releases/2007/09/070910132848.htm
ScienceDaily (Sep. 12, 2007) — Nearly 30 years after Nobel laureate
Linus Pauling famously and controversially suggested that vitamin C
supplements can prevent cancer, a team of Johns Hopkins scientists
have shown that in mice at least, vitamin C - and potentially other
antioxidants - can indeed inhibit the growth of some tumors ¯ just not
in the manner suggested by years of investigation.
See also:
Health & Medicine
Cancer
Lung Cancer
Brain Tumor
Plants & Animals
Mice
Biotechnology
Biology
Reference
Polyphenol antioxidant
Vitamin E
B vitamins
Antioxidant
The conventional wisdom of how antioxidants such as vitamin C help
prevent cancer growth is that they grab up volatile oxygen free
radical molecules and prevent the damage they are known to do to our
delicate DNA. The Hopkins study, led by Chi Dang, M.D., Ph.D.,
professor of medicine and oncology and Johns Hopkins Family Professor
in Oncology Research, unexpectedly found that the antioxidants' actual
role may be to destabilize a tumor's ability to grow under
oxygen-starved conditions. Their work is detailed this week in Cancer
Cell.
"The potential anticancer benefits of antioxidants have been the
driving force for many clinical and preclinical studies," says Dang.
"By uncovering the mechanism behind antioxidants, we are now better
suited to maximize their therapeutic use."
"Once again, this work demonstrates the irreplaceable value of letting
researchers follow their scientific noses wherever it leads them,"
Dang adds.
The authors do caution that while vitamin C is still essential for
good health, this study is preliminary and people should not rush out
and buy bulk supplies of antioxidants as a means of cancer prevention.
The Johns Hopkins investigators discovered the surprise antioxidant
mechanism while looking at mice implanted with either human lymphoma
(a blood cancer) or human liver cancer cells. Both of these cancers
produce high levels of free radicals that can be suppressed by feeding
the mice supplements of antioxidants, either vitamin C or
N-acetylcysteine (NAC).
However, when the Hopkins team examined cancer cells from
cancer-implanted mice not fed the antioxidants, they noticed the
absence of any significant DNA damage. "Clearly, if DNA damage was not
in play as a cause of the cancer, then whatever the antioxidants were
doing to help was also not related to DNA damage," says Ping Gao,
Ph.D, lead author of the paper.
That conclusion led Gao and Dang to suspect that some other mechanism
was involved, such as a protein known to be dependent on free radicals
called HIF-1 (hypoxia-induced factor), which was discovered over a
decade ago by Hopkins researcher and co-author Gregg Semenza, M.D.,
Ph.D., director of the Program in Vascular Cell Engineering. Indeed,
they found that while this protein was abundant in untreated cancer
cells taken from the mice, it disappeared in vitamin C-treated cells
taken from similar animals.
"When a cell lacks oxygen, HIF-1 helps it compensate," explains Dang.
"HIF-1 helps an oxygen-starved cell convert sugar to energy without
using oxygen and also initiates the construction of new blood vessels
to bring in a fresh oxygen supply."
Some rapidly growing tumors consume enough energy to easily suck out
the available oxygen in their vicinity, making HIF-1 absolutely
critical for their continued survival. But HIF-1 can only operate if
it has a supply of free radicals. Antioxidants remove these free
radicals and stop HIF-1, and the tumor, in its tracks.
The authors confirmed the im****tance of this "hypoxia protein" by
creating cancer cells with a genetic variant of HIF-1 that did not
require free radicals to be stable. In these cells, antioxidants no
longer had any cancer-fighting power.
The research was funded by the National Institutes of Health.
Authors on the paper are Dean Felsher of Stanford; and Gao, Huafeng
Zhang, Ramani Dinavahi, Feng Li, Yan Xiang, Venu Raman, Zaver
Bhujwalla, Linzhao Cheng, Jonathan Pevsner, Linda Lee, Gregg Semenza
and Dang of Johns Hopkins.
Adapted from materials provided by Johns Hopkins Medical Institutions.
Need to cite this story in your essay, paper, or re****t? Use one of
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Johns Hopkins Medical Institutions (2007, September 12). How Vitamin C
Stops Cancer. ScienceDaily. Retrieved October 30, 2007, from
http://www.sciencedaily.com/releases/2007/09/070910132848.htm
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