The use of high-dose intravenous vitamin C dates back to the work of Dr. Linus Pauling in the 1970s. After his seminal work on the nature of the chemical bond between molecules, which won him the Nobel Prize in Chemistry in 1954, Pauling turned to biochemistry, and eventually to the area of nutritional supplements, where he became a notable advocate of vitamin C. Laboratory studies showed that high doses of vitamin C killed cancer cells. A Scottish surgeon, Ewan Cameron, thus implemented clinical trials of high-dose vitamin C in cancer patients, and eventually high doses of vitamin C came to be used in cancer patients, often administered intravenously. This treatment fell into disrepute after the Mayo Clinic conducted trials with vitamin C that showed no effect. But the Mayo Clinic investigators hadn’t administered the compound intravenously or in the doses recommended by the previous investigators. Instead, they gave it orally, and in lower doses.
The use of intravenous vitamin C then languished, administered only in the most alternative of cancer clinics, until NIH researcher Mark Levine began investigating it in his laboratory. Levine found that the route of administration of vitamin C had a major effect on its concentration in the body. The lab studies of vitamin C showed that a concentration of 5-40 millimoles of vitamin C per liter is necessary to kill cancer cells. Levine’s work showed that this concentration is not achievable through taking vitamin C orally. The body tightly regulates the amount of vitamin C that we absorb through the GI tract, and no matter how much vitamin C we swallow, we can’t get this level of vitamin C in the bloodstream. However, when vitamin C is given intravenously, it’s able to bypass this tight regulation. With sufficient doses, it’s not a challenge to get blood levels of vitamin C high enough to kill cancer cells.
With Levine’s work, high-dose intravenous vitamin C (IVC) began to look more interesting again. However, it took the success of two ovarian cancer patients taking high-dose IVC along with their chemotherapy, at a Kansas clinic, to get IVC into proper clinical trials. Dr. Jeanne Drisko at the University of Kansas noted and published the results of these patients, who both remained alive at least 3 years, following the use of IVC and other antioxidants in conjunction with chemotherapy. She began the research program that has led to a resurgence of scientific interest in IVC, and to several clinical studies that we at the Block Center feel demonstrate the safety and the potential for efficacy of this non-toxic therapy. The most recent of her papers appeared February 5th in the journal Science Translational Medicine.
Vitamin C is well known as an antioxidant. Ideas about the interaction of antioxidants and cancer cells, as well as antioxidants and chemotherapy, including IVC, have become more nuanced in the past few years however, because of discoveries about just how these antioxidants work inside cancer cells, especially when they are given at high concentrations. Scientists in several labs around the globe have recently published papers demonstrating that when high doses of antioxidants are administered to cancer cells, they frequently stop acting like antioxidants, and start acting as pro-oxidants (the opposite of antioxidants), promoting free-radical activity and in fact, generating free radicals. At the same time, they retain their antioxidant activity in normal cells. We summarized some of these studies in a blog titled “Antioxidants as pro-oxidants,” posted on November 12, 2013.
This paradoxical mechanism, and the reason it occurs, has been elucidated for vitamin C by the work in the laboratory of Dr. Drisko and her colleagues. The mechanism is based on this: vitamin C has a distinctive reaction with metal ions, particularly iron. When high-dose vitamin C interacts with metal ions like iron, which are present in high levels in tumors, it creates hydrogen peroxide. Hydrogen peroxide is a pro-oxidant, capable of causing free radical damage. In normal cells, the enzyme catalase disables hydrogen peroxide. Thus, in normal cells, vitamin C retains its antioxidant effect. Tumor cells, however, lack catalase, and cancers are thus vulnerable to damage from hydrogen peroxide. Tumor cells also selectively take up vitamin C, so they accumulate it to higher levels than normal cells – increasing their vulnerability to hydrogen peroxide. So it appears that high-dose IVC preferentially targets cancer cells with hydrogen peroxide. This explains why IVC, even in surprisingly high doses, can be harmless (or even beneficial) to normal cells, but at the same time, kill tumor cells. Furthermore, since IVC creates a pro-oxidant effect, it is unlikely to counteract the effect of chemotherapy.
A further study in the University of Kansas labs showed that intravenous vitamin C at correct doses in fact synergized with carboplatin and Taxol, the chemotherapy drugs usually given to ovarian cancer patients, and enhanced their effects in mice bearing ovarian tumors. Drisko and her colleagues also have been running clinical trials of IVC in ovarian cancer patients, and have been able to validate that it reduced side effects of chemotherapy in these patients. Larger-scale trials are needed to ascertain whether IVC really improves the effectiveness of chemotherapy in patients, as it did in mice. But at this point it does appear safe for use alongside chemotherapy, and potentially effective. In the near future, the journal Integrative Cancer Therapies (Dr. Block is Editor-in-Chief) expects to publish an article reviewing all of the human studies on intravenous vitamin C in cancer, which affirms the safety and potential efficacy of this treatment.
The Block Center does make IVC available to our chemotherapy patients, as one part of our comprehensive, individualized approach to treatment. There are few concerns with side effects of high-dose IVC, but there is a blood test for inherited glucose-5-phosphate dehydrogenase (G6PD) enzyme deficiency, which patients must undergo before treatment. Also, patients with the disorder hemochromatosis (too much iron in the blood) should not have IVC treatment.