Vitamin C affects the immune system, which must be functioning well to combat cancer. White blood cells (WBCs), the immune system's primary fighting force, contain the vitamin. Reviews of the research show that WBCs taken from cancer patents have less vitamin C than do WBCs from healthy people.47,48

Treating cancer with vitamin C has been a controversial issue since Linus Pauling, the Nobel Prize-winning scientist, began to advocate it years ago. Working with a Scottish surgeon. Ewan Cameron, Pauling decided to investigate the possibility that vitamin C might help patients who already have cancer.49 hundred terminal cancer patients were given 10 grams of vitamin C daily (2.5 grams four times per day) and followed until death. They lived an average of 210 days, compared with hospital records of 1,000 "matched controls" (similar patients) who aver aged only 50 days. A follow-up showed an even wider gap between the vitamin C and control groups.50

The rest of the research community was concerned about these results, in part because the 1,000 control patients received no placebo.51 In other words, the patients taking the vitamin might have lived longer because they believed the therapy might have helped them.* Ironically, while conventional medicine has very little interest in psychological intervention in cancer treatment, medical doctors feel no qualms about using the argument that placebo effect, a psychological intervention, might extend life significantly.

*In a placebo-controlled trial, all patients know they might be receiving a treatment or they might be getting an inert placebo. The function of such a control is to remove the psychological advantage of getting something from the purely physical effects of the treatment. Because patients don't know whether they received the real treatment or the placebo, the real treatment group has no psychological advantage over the placebo group. Otherwise there would be a bias; it is well known that people who merely think they have received a real treatment often do better physically.

The Mayo Clinic attempted to test Cameron and Pauling's results. The Mayo Clinic paper, which did have a placebo-control group, reported that vitamin C did not help.52 Linus Pauling protested that the two trials weren't equivalent because most of the Mayo Clinic patients had had chemotherapy, while his patients had not. This distinction might be important because chemotherapy impairs the immune system; and, as mentioned earlier, one way in which vitamin C might help cancer patients is by boosting immune function. Theoretically, a damaged immune system might not be able to take advantage of supplemental vitamin C.

In response, the Mayo Clinic proceeded to do another study testing vitamin C. This time they used patients who had had no chemotherapy.53 The researchers said that this trial was ethical because "there is no known form of chemotherapy for colorectal cancer that has been demonstrated to produce substantive palliative benefit or extension of survival.''54 For this reason, the second Mayo Clinic study was limited to colon cancer patients. Once again, the researchers claimed that vitamin C was useless.