Ageing is a process that involves numerous irreversible changes. There are many theories trying to explain its causes (e.g. genetic predispositions, lifestyle and other external/environmental factors). A lot however remains unclear and unexplained or even contradictory. Changes occur both on molecular level and on the level of the organism. Reaction rates of these processes can be accelerated or decelerated by external factors.
One external factor that can influence the reaction rate for ageing is the presence of reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS are called free radicals. They react with macromolecules of cell membranes, molecular structures and nucleic acids. As such they gradually influence their function in a negative way. Antioxidants can reduce the activity of these free radicals. Antioxidants are a natural part of food. However, it is not clear what amount and which form is most effective. The phenomenon of ageing is very complex. It is strongly influenced by an individual's health, and our ageing population poses many social, economic and philosophical challenges.