vitamins C, E
Cellular systems are subject to constant oxidative stress by reactive oxygen species (ROS). Oxidative stress has been implicated as a factor in the aetiology of a variety of degenerative diseases and in the ageing process. ROS are capable of causing adverse modifications of macromolecules including lipids, DNA and proteins. Cellular systems also possess antioxidant defence systems whose role is to minimise adverse oxidative changes. The balance between prooxidant forces and antioxidant defence systems influences the body's susceptibility to prooxidant damage. A variety of nutrient and non-nutrient dietary constituents, including vitamins C, E and carotenoids, have been shown to affect this praoxidant/antioxidant balance and consequent risk of certain degenerative diseases. Defining optimal intakes of these nutrients and non-nutrients is a key challenge in nutrition research. (C) 1998 Elsevier Science Ltd. All rights reserved.