Dosing up artificially on antioxidants/vitamins is unnatural and I question wether taking them for a long period is actually beneficial.
Why not try the best means?Colorful fruit & veges! For veges - Broccoli, Spinach, Beetroot, carrots, tomatoes, etc. With fruit - Blueberries (one of the most antioxidant rich foods), raspberries, strawberries, grapes etc. Anything with good colour is great, and not only are you getting antioxidants, but minerals, vitamins & other phytonutrients