|Cancer hopes as Vitamin C injections kill mice tumours
Herald | August 5, 2008
Vitamin C that is injected rather than swallowed could provide a new lifeline for cancer patients with a poor prognosis and few treatment options, according to new research.
Scientists say the therapy halved the growth of aggressive tumours in mice, killing cancer cells while leaving healthy tissue unharmed.
Tackling cancer with vitamin C would also have the added advantage of being less expensive, the research claims.
The body usually keeps tight control of vitamin C levels in the blood.
However, a new US-based investigation, led by Dr Qi Chen from the National Institutes of Health in Maryland, Ohio, found that the mechanism can be by-passed if the vitamin is injected straight into the bloodstream instead of passing through the digestive system.
When this is done it releases the powerful anti-cancer potential of the vitamin.
Experiments showed that high levels of vitamin C in the blood generate hydrogen peroxide, which is lethal to tumours. The chemical forms in the spaces between cancer cells, damaging membranes, upsetting metabolism and scrambling DNA.
Even the growth of aggressive, hard-to-treat cancers was held back in the studies. But healthy tissues appeared to resist the effects.
The use of high-dose vitamin C as a complementary or alternative cancer treatment was first promoted in the 1970s. Patients have taken the vitamin both by mouth and intravenously. But despite some positive outcomes, there has been insufficient reliable evidence that the therapy works leading conventional cancer experts to dismiss claims that vitamin C can treat cancer.
Dr Chen's investigation involved testing the effects of vitamin C on laboratory cell lines and cancer-ridden mice.
Laboratory tests showed that two hours of exposure to the vitamin significantly reduced the survival of ovarian, pancreatic and brain tumour cancer cells.
Similar results were achieved when mice bearing the same kinds of tumours were injected with vitamin C.
Writing in the journal Proceedings of the National Academy of Sciences, the scientists said: "Pharmacologic concentrations of ascorbate decreased tumour volumes 41-53% in diverse cancer types known for both their aggressive growth and limited treatment options."
They said a "rapid and sustained increase" in hydrogen peroxide was detected in tumour fluids within 30 minutes of the treatment commencing.
An early stage patient study showed that similar therapeutic levels of vitamin C in the blood could be achieved when ascorbate was administered intravenously in humans.
The scientist added: "A regimen of daily pharmacologic ascorbate treatment significantly decreased growth rates of ovarian, pancreatic and glioblastoma tumours established in mice.
"Similar pharmacologic concentrations were readily achieved in humans given ascorbate intravenously. These data suggest that ascorbate as a prodrug may have benefits in cancers with poor prognosis and limited therapeutic options."
Dr Alison Ross, science information officer at Cancer Research UK, said: "This is encouraging work but it's at a very early stage because it involves cells grown in the lab and mice. Much more research is needed before we'll know whether vitamin C could be a viable cancer treatment in the future.
"There is currently no evidence from clinical trials in humans that injecting or consuming vitamin C is an effective way to treat cancer. Some research even suggests that high doses of antioxidants can make cancer treatment less effective, reducing the benefits of radiotherapy and chemotherapy."
Vitamin C supplements have been hailed since the 1970s as an aid for fighting colds, principally thanks to the US Nobel Prizewinning chemist Dr Linus Pauling, who championed it.
However, in July last year, Australian and Finnish scientists describe d the claim as a myth, saying that there was no evidence that, for the average person, taking extra vitamin C can stop coughs and sneezes.