For years antioxidants have been touted as a way to protect against cancer based on very little hard clinical data. A large trial in the 1990’s in lung cancer prevention showed the opposite effect: that adults taking large doses of antioxidants were more likely to get lung cancer. Now comes a study in experimental animals using a mouse melanoma model. The animals were fed N-acetyl cysteine or NAC and Trolox, a vitamin E analogue, as part of an experiment in which they were given melanoma. The animals who received the NAC and Trolox developed accelerated lymph-node metastases in spite of the fact that the oxidation reduction ratio of glutathione in metastatic lymph nodes was improved. This change in ratio, however, caused the melanoma cells to act in a more virulent manner. Does this translate into meaningful clinical evidence? Dr. Stark says, “Not yet, but the evidence in favor of harm from anti-oxidants is mounting, and this well-done animal experiment is further evidence. What the lung cancer vitamin trial taught us, if anything, is that we cannot replicate in pill form whatever benefit naturally occurring anti-oxidants, such as those seen in fruits and vegetables, can provide. This study also gave exogenous drugs, not foods, to the animals and they did poorly. Based on this paper and a mountain of other data, it would be bad advice to recommend to patients that they take large doses of vitamins or anti-oxidants while undergoing cancer therapy. It’s not clear that the scientific community is very interested in pursuing this line of research, at least at the moment, so the definitive answer may not be forthcoming any time soon.”
Update 2020: there has been some additional interest in this subject since this article was posted in 2015. In 2017 a thoughtful review published in Integrative Cancer Therapies concluded that much work neeeded to be done to assess whether there was any role to adding oxidants to cancer therapy. The article is available in the public domain. Dr. Stark can email you a copy. Subsequent articles have shed no additional light. The problem of getting funding for such research when there is no patentable product being tested remains.