Vitamin C has been used as an alternative therapy for cancer for several decadesbut previous scientific research into orally administered vitamin C was able to find little evidence of effectiveness.
However, a new study carried out by the University of Kansas suggests that giving some cancer patients high doses of vitamin C intravenously rather than orally, alongside conventional chemotherapy, may help to kill cancer cells and also reduce some of the toxic side effects.
The research found that giving infused vitamin C together with two conventional chemotherapy drugs, carboplatin and paclitaxel, stopped ovarian cancer in the laboratory and also reduced toxic side effects of chemotherapy in ovarian cancer patients.
Senior study author Qi Chen, Assistant Professor in the Department of Pharmacology, Toxicology and Therapeutics at the Kansas University Medical Centre, explains:
"What we've discovered is that, because of its pharmacokinetic differences, intravenous vitamin C, as opposed to oral vitamin C, kills some cancer cells without harming normal tissues."
For their clinical trial, the researchers recruited 27 patients who had just been diagnosed with stage 3 or stage 4 ovarian cancer.
They all underwent conventional chemotherapy with paclitaxel or carboplatin, but some also received high doses of vitamin C intravenously. They were then followed for 5 years.
The researchers found that, compared with the patients who did not receive vitamin C in addition to conventional chemotherapy, the toxic effects of the therapy tended to be less in the patients given vitamin C.
In another experiment, the researchers found vitamin C killed cancer cells in mice with ovarian cancer, but only at concentrations that can be achieved if given intravenously. They noticed no toxic effects or changes due to chemotherapy in the animals' livers, kidneys and spleens.
Co-researcher Dr. Jeanne Drisko, who specialises in integrative medicine, says:
"We now have a better understanding of vitamin C's anti-cancer action, plus a clear safety profile, and biological and clinical plausibility with a firm foundation to proceed. Taken together, our data provide strong evidence to justify larger and robust clinical trials to definitively examine the benefit of adding vitamin C to conventional chemotherapy."
The study was published in Science Translational Medicine.