RESUMEN
Much degenerative disease including cancer, diabetes, cardiovascular and rheumatoid disease is now associated with the tissue- and DNA-damaging effects of reactive oxygen species [ROS]. Drugs and environmental chemicals exacerbate the formation of ROS and enhance their toxic effects. However, two interrelated biological defence systems protect against the adverse effects of ROS and environmental chemicals. The 'antioxidant defence system' of glutathione [GSH], superoxide dismutase, GSH peroxidase, and the antioxidants/radical scavengers, vitamin C, vitamin E and retinoids, protect against ROS; and the 'chemical detoxication system' of cytochromes P450, epoxide hydrase, GSH S-transferases, glucuronyl transferases etc., deactivate drugs and environmental chemicals. Both of these biological defence systems need constant replenishment from the daily diet, protein for synthesis of vital enzymes and GSH, lipids and lipotropes [essential fatty acids, choline] for synthesis of phospholipids and elaboration of biological membranes, vitamins [ascorbate, tocopherols, retinoids] as antioxidants and radical scavengers, and energy to produce NADPH which drives and reactivates both systems. Fasting activates cytochrome P4502E1 which generates ROS, as does alcohol; similarly, excessive calories results in conversion of excess energy into ROS production. Conversely, a diet rich in fruit and vegetables, fish, dairy products, whole cereals and pulses, will provide adequate protection against ROS, oxidative stress and risk of degenerative disease