Should Antioxidant Supplementation Be Contraindicated During Active Cancer Treatment?

Dear Editor, Many patients undergoing cancer treatment take antioxidant supplements in the belief that they are harmless or protective. Emerging mechanistic evidence suggests this assumption deserves urgent scrutiny, and I write to propose that clinicians proactively counsel patients on this point. According to PubMed, reactive oxygen species act on a gradient in which high levels limit cancer cell survival during certain windows of initiation and progression, such that dietary antioxidant supplementation—which has generally proven ineffective or detrimental in clinical trials-may promote cancer cell survival during those windows. Oxidative stress, in other words, is partly a barrier the tumor must overcome, and lowering it pharmacologically may remove that barrier.