Reviewing the Evidence Base for Supplemental Antioxidant Nutrients and Cancer Prevention: What We’ve Learned

A large body of research has investigated the potential role of supplemental antioxidant nutrients (beta-carotene and other carotenoids, vitamin E, vitamin C, selenium) in the prevention of cancer. This presentation will review the scientific evidence on supplemental antioxidant nutrients and cancer prevention, with an emphasis on large randomized controlled trials of these nutrients for the primary and secondary prevention of various cancers in humans. As will be discussed, results from completed trials in general indicate no clear benefit to the use of supplemental antioxidant nutrients for cancer prevention, with some studies finding evidence of harm with certain nutrient supplements in certain populations. At the same time, some studies have suggested promising leads for further evaluation, stimulating a second generation of trials involving supplemental antioxidant nutrients. One such trial is SELECT, which is an ambitious trial that evaluates supplemental vitamin E and selenium (alone and in combination) for the prevention of prostate and other cancers in 32,400 men. Research Needs and Conclusions: The evidence base on antioxidant nutrients and cancer prevention continues to evolve. Randomized trials of supplemental antioxidant nutrients for the primary prevention of cancer are extremely lengthy and expensive, and it will be several year