Increased intracellular levels of reactive oxygen species (ROS) may result in tissue damage and are therefore associated with various diseases, especially with cancer. Apart from their potentially harmful functions, ROS have been identified as important mediators of essential cellular processes like apoptosis. Antioxidants are the cellular antagonists of ROS and act to neutralize the cytotoxic impact of oxyradicals. In healthy individuals, antioxidant systems serve to maintain intracellular ROS levels below a certain threshold, permitting the functionality of essential ROS-mediated signaling...