Vitamin C has long been the most widely used dietary supplement, and much of the initial excitement surrounding this vitamin can be traced back to studies conducted in the 1970s by two-time Nobel Prize winner Linus Pauling. A chemist by training, Dr. Pauling had publicly questioned the adequacy of the Recommended Daily Allowance (RDA) for vitamin C, and he suggested that taking gram doses of vitamin C (1000 mg or more) could be effective in the prevention and treatment of colds. At the time, the RDA was a mere 45 mg per day, an amount considered sufficient to prevent scurvy, the classic disease of vitamin C deficiency.

Pauling took the controversy up another notch when he proposed daily doses of 5 to 30 grams for the treatment of advanced cancers. To this day, the very mention of Pauling’s vitamin C research still sparks heated arguments among medical professionals — oncologists in particular.

Clinical studies of the potential therapeutic value of high-dose vitamin C began in Scotland in 1971. The findings from these early investigations were dramatic indeed. Three studies showed a four-fold increase in survival, and one other showed a nearly six-fold increase in survival for patients with advanced cancer. In that last study, 100 patients with “terminal” cancer were compared to 1000 patients who had been given the same bleak prognosis. As with the previous studies, vitamin C was first given intravenously and then orally, in the range of 10 to 30 grams per day. In addition to prolonging survival, many patients receiving vitamin C reported having more energy and a greater overall sense of well-being.

Understandably, these findings attracted much media attention and ignited an explosion of public interest in using vitamin C for cancer therapy. Many thousands of cancer patients began self-prescribing the vitamin. At the same time, however, some scientists sharply criticized Pauling’s research on the grounds that his early studies were not randomized controlled clinical trials, the “gold standard” of medical research. For this reason, the studies’ findings were deemed unreliable or at best preliminary.

Controlled clinical trials are indeed the best way to assess the true value of any proposed treatment strategy. In the case of vitamin C, the ideal study would randomly assign cancer patients to receive either vitamin C or a placebo (a substance having no biological or therapeutic activity), and to do so without the patients knowing which one they were receiving. Researchers from the Mayo Clinic eventually did conduct two randomized clinical trials. Neither trial found a significant survival advantage with vitamin C. Since then, many authorities have cited the Mayo Clinic research as “overwhelming” evidence that vitamin C was not an effective treatment.

But let’s take a closer look at how these clinical trials were done. In the first study, the cancers were too far advanced to reasonably expect any intervention to affect the outcome (average survival for all patients was only 51 days). A more fundamental flaw of both clinical trials was that the researchers provided vitamin C only in oral form. (In Part 2, we show why the oral method is inadequate.) Moreover, the Mayo Clinic team neglected to follow Dr. Pauling’s recommended protocol for achieving “bowel tolerance” — that is, in order to prevent diarrhea, the oral dose was supposed to have been increased gradually over time.

So where do we stand today? One thing we do know is that the jury is still out on vitamin C as a potential cure for cancer. Though a clinical trial is now in progress in Kansas City, no one has adequately tested Pauling’s hypothesis. To date, at least six clinical studies have concluded that high-dose vitamin C (both intravenous and oral vitamin C) did increase survival in patients with advanced cancers. Only one randomized trial has examined intravenous vitamin C's impact on advanced cancer, and this did not show a survival benefit. In Part 2, we’ll talk about some of the most recent reports concerning vitamin C as cancer therapy, and why, in particular, the intravenous approach may be one of the keys to success.

© Copyright 2010 Mark N. Mead. All Rights Reserved.