ROLE OF FREE RADICALS IN HEALTH AND DISEASE
Recently, there has been an increasing awareness among people in the prevention of disease and more especially the role of free radicals in health and disease. The oxidative properties of oxygen play a vital role in diverse biological functions such as utilization of nutrients, electron transport to produce ATP and the removal of xenobiotics. Despite the fact that oxygen is essential for life, it can also provoke damaging oxidative events within cells. Oxygen, by its transformation to more reactive forms like superoxide radical (O2−•), hydroxyl radical (•OH) and hydrogen peroxide (H2O2) can nick DNA causing mutagenesis and carcinogenesis, damage essential enzymes, resulting in loss of enzyme activity, as well as denature structural proteins and can also provoke uncontrolled chain reactions, such as lipid peroxidation or autooxidation reactions (e.g. polymerization of catecholamines). Reactive oxygen species are generated by the mitochondria as toxic by-products of oxidative phosphorylation or from exogenous sources. Endogenous free radicals could also be generated from immune cell activation, inflammation, mental stress, excessive exercise, ischemia, infection, aging, cancer. Many forms of cancer are thought to be the result of reactions between free radicals and DNA, resulting in mutations that adversely affect the cell cycle and eventually lead to malignancy. Free radical damage within cells has been linked to a wide range of diseases including arthritis, arteriosclerosis, Alzheimer’s diseases and diabetes. It has been estimated that the average person has around 10,000–20,000 free radicals attacking each body cell each day. Although free radicals appear to be the main factor in many diseases, cells have evolved defense mechanisms for protection against ROS -mediated oxidative damage by producing antioxidants, which are either naturally produced in situ, or externally supplied through foods and supplements....
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