First popularized by the Nobel Prize-winning chemist Linus Pauling, vitamin C has long been used by alternative health practitioners to support cancer patients. But the practice has been met with skepticism by the medical establishment. Two previous clinical trials of vitamin C failed to find any effect, but these studies used oral vitamin supplements, which cannot generate the high vitamin C levels in the blood that proponents argue is necessary to fight cancer. However, researchers at the University of Kansas have now published a multi-pronged study showing a positive effect of high-dose vitamin C therapy, widely practiced in alternative medicine, for ovarian cancer patients, as well as experimental results that help explain the mechanism behind vitamin C’s cancer-fighting properties.

The researchers gave intravenous (IV) vitamin C to 27 women who were undergoing conventional chemotherapy treatment for advanced ovarian cancer, and found that these women experienced far fewer toxic effects from the chemo drugs. To understand this phenomenon, they exposed ovarian cancer cells and mice with ovarian cancer to vitamin C in comparable amounts to those given to their patients. Vitamin C is typically considered an antioxidant that removes excess oxidative molecules, such as so-called “free radicals,” which can be harmful to cells. But at the high levels that the investigators used, vitamin C took on an opposite role—it promoted oxidation through the formation of hydrogen peroxide.

Because cancer cells are especially vulnerable to damage from oxidation, while normal cells are relatively well-protected from it, the vitamin C treatment was able to selectively target cancel cells—making them more vulnerable to chemotherapy drugs—and leave healthy cells intact. Hopefully these important findings will prompt additional research and, more importantly, encourage more doctors to offer the therapy to cancer patients.

(Source: Science Translational Medicine, 2014; 6: 222ra18.)