Cellular systems are always subject to oxidation stress owing to the reactive oxygen system effect (ROS). ROS can generate unfavourable modifications in such macromolecules as lipids, DNA, and proteins. Cellular systems have antioxidant systems to neutralize those unfavourable changes produced by ROS. In human organisms, there are enzymes that influence the equilibrium between pro-oxidant and antioxidant; they also decide oxidizable changes and the risky possibility of degenerative diseases to develop. The potential degeneration types involve glutathione peroxidase (GSHPX), superoxide dismutase (SOD), and catalase. Vitamins C and E, as well as carotenoids and flavonoids play a role similar to the role of enzymes as indicated above. Regarding the fact that they are usually supplied with food, it is an important task and a real challenge for scientists specialised in nutrition to determine optimal doses of both the compounds and nutritive components containing them.