The philosophy behind exo/endo/existing antioxidants and our built-in oxidant and antioxidant system.

Free radicals (FRs) and oxidants (Os) have different vital activities in our bodies. Biological redox reactions are the major source for FRs-Os. In normal cases, they are under the control of our body's existing antioxidant (antiO) system. If their amounts exceeds a certain limit, they start to attack and damage various macromolecules and cells. In the case of DNA damage, dangerous diseases such as cancer "the human killer" can be elevated. The expression and regulation of the genes coding for the endogenous (endo) antiO enzymes are important for our health. Genetic polymorphism between different populations reflects the differences between individuals and populations abilities to produce antiOs. This review will discuss general aspects about different types of FRs-Os and antiOs as well as their direct and indirect interaction with genetic materials. The benefit of the antiOs, which can do a lot for our health, will be highlighted.