How do antioxidants prevent chronic diseases such as cancer, heart disease, and macular degeneration?

Maybe: For macular degeneration - free radicals appear to play a significant role. There is currently a prevention arm of the areds which is looking at supplements in preventing the progression of macular degeneration. It's often better to eat a good diet, exercise and reduce other risk factors than take supplements. Oh yes, please don't smoke!

Oxidative stress: We know oxidative stress can cause changes in cells and become cancerous. So logic would say, antioxidants would prevent cancer.But unfortunately studies to this day have yet to prove antioxidants do anything to prevent cancer. This needs to be investigated further.