Antioxidant supplements provide no benefit, may even be harmful. See 2007 meta-analysis by Goran Bjelakovic, Dimitrinka Nikolova, Lars Gluud, Rosa G. Simonetti, and Christian Gluud, published in JAMA:
“Mortality in Randomized Trials of Antioxidant Supplements for Primary and Secondary Prevention: Systematic Review and Meta-analysis”.