The late Linus Pauling was a chemical genius, but he, like everyone else in the world, was not correct all the time. When he was competing with Crick and Watson to identify the structure of DNA, he wrote a paper claiming that DNA was a triple helix. This is chemically impossible, but he got the paper published anyway because he was a member of the National Academy of Sciences. In the latter years of his life, he concluded that mega doses of vitamin C would cure the common cold and be a viable treatment for cancer. Again, he was wrong. The truth, as outlined in the forthcoming study, shows that the opposite is true.
Vitamin C Supplements may Reduce Benefit from Wide Range of Anticancer
DrugsSubject: Vitamin C Supplements may Reduce Benefit from Wide Range of
Anticancer Drugs
Embargoed for Release:
Ocotober 1, 2008, 12:01 a.m.
Vitamin C Supplements may Reduce Benefit from Wide Range of Anticancer Drugs
PHILADELPHIA – In pre-clinical studies, vitamin C appears to substantially
reduce the effectiveness of anticancer drugs, say researchers at Memorial
Sloan-Kettering Cancer Center.
These new findings, published in the October 1 issue of Cancer Research, a
publication of the American Association of Cancer Research (AACR), came from
studying laboratory cancer cells and mice, but the study’s authors say the same
mechanism may affect patient outcomes, although they add this premise needs to
be tested.
“The use of vitamin C supplements could have the potential to reduce the ability
of patients to respond to therapy,” said Heaney, an Associate Attending
Physician at Memorial Sloan-Kettering Cancer Center.
Use of vitamin C during cancer treatment has been controversial. Some studies
have suggested that because vitamin C is an antioxidant it might be beneficial
to cancer patients. But some classes of chemotherapy drugs produce “oxygen free
radicals,” unpaired oxygen molecules that can fatally react with other molecules
in a cell, forcing cell death. In this theory, vitamin C could sop up the
radicals, keeping the cancer cell alive despite chemotherapy treatment.
Heaney and his colleagues tested a wide variety of chemotherapy drugs – those
that produce reactive oxygen and those that work in other ways – on cancer cells
in the laboratory, that were pretreated with dehydroascorbic acid (DHA), the
form that ascorbic acid (vitamin C) takes to enter cells.
They found to their surprise that every chemotherapy drug they tested – which
included targeted agents like Gleevec – did not work as well if cells were
pretreated with vitamin C, as they did on untreated cancer cells. In the cell
culture experiments, 30 to 70 percent less cancer cells treated with vitamin C
were killed depending on the drug tested.
They then checked these findings by implanting the cancer cells into mice, and
again found that, in an animal model system, while chemotherapy kept untreated
cancer in check, tumors grew more rapidly in mice that were given cancer
pretreated with vitamin C.
The research team, which includes researchers from Columbia University, then
delved into the mechanism by which vitamin C may be protecting these cells, and
discovered that it wasn’t because the nutrient was neutralizing oxygen-free
radicals.
They found instead that DHA was restoring viability to the cancer cell’s damaged
mitochondria – the cell’s all-important power plant that, when injured, sends
signals to force a cell to die.
“Vitamin C appears to protect the mitochondria from extensive damage, thus
saving the cell,” Heaney said. “And whether directly or not, all anticancer
drugs work to disrupt the mitochondria to push cell death.”
Heaney says that the amount of DHA used in the experiments resulted in an
intracellular buildup similar to what could be seen in cancer patients using
large supplemental doses of vitamin C.
Researchers at Memorial Sloan-Kettering Cancer Center have long been researching
the connection between vitamin C and cancer therapy, and these new findings
expand on their earlier observation that vitamin C seems to accumulate within
cancer cells more than in normal cells.
“We recognized that DHA is the form of vitamin C that gets into cells, and that
the tumor microenvironment allows cancer cells to convert more vitamin C into
DHA,” he said. “Inside the cell, DHA is converted back into ascorbic acid, and
it gets trapped there and so is available to safeguard the cell.”
Heaney says that he suspects that vitamin C is good for the cells of normal
tissue because it provides more protection for the mitochondria, and thus
probably extends cell life. “But that isn’t what you want when you are trying to
eliminate cancer cells,” said Heaney, who notes that cancer patients should eat
a healthy diet, which includes foods rich in vitamin C. It is use of large doses
of over-the-counter vitamin C that is worrisome, he says.
END
Many so-called alternative physicians inject vitamin C into the veins of cancer patients. This procedure often works, but not because vitamin C is acting as an anti-oxidant. To the contrary, pharmacological doses of vitamin C produce hydrogen peroxide when injected into the blood. The hydrogen peroxide enters the cancer cell and kills it. The hydrogen peroxide can also be generated within the cancer cells. Large oral doses of vitamin C do not accomplish these results. As the study above shows, mega oral doses of vitamin C can promote cancer cell growth by stabilizing the mitochondria.
Now you know. I am never going to discuss this topic again.
Stay tuned...
Grouppe Kurosawa, Medicine in the Public Interest
