Antioxidants - Vitamins As Antioxidants, The Vitamins, Current Research On Antioxidants
Posted Sep 11 2009 4:56pm
In biology, antioxidants are scavengers of small, reactive molecules known as free radicals and include intracellular enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase. Antioxidants can also be extracellular originating as exogenous cofactors such as vitamins. Nutrients functioning as antioxidants include vitamins, for example ascorbic acid (vitamin C), tocopherol (vitamin E) and vitamin A.
Trace elements such as the divalent metal ions selenium and zinc also have antioxidant activity as does uric acid, an endogenous product of purine metabolism. Free radicals are molecules with one or more unpaired electrons, which can react rapidly with other molecules in processes of oxidation. They are the normal products of metabolism and are usually controlled by the antioxidants produced by the body or taken in as nutrients.
However, stress, aging, and environmental sources such as polluted air and cigarette smoke can add to the number of free radicals in the body, creating an imbalance. The highly reactive free radicals can damage nucleic acids and have been linked to changes that accompany aging (such as age-related macular degeneration, an important cause of blindness in older people) and with disease processes that lead to cancer, heart disease, and stroke.
The brain is particularly vulnerable to oxidative stress. Free radicals play an important role in a number of neurological conditions including stroke, Parkinson disease, Alzheimer disease, epilepsy and schizophrenia. Some other diseases in which oxidative stress and depletion of antioxidant defence mechanisms are prominent features include hepatic cirrhosis, pre-eclampsia, pancreatitis, rheumatoid arthritis, mitochondrial diseases, systemic sclerosis, malaria, neonatal oxidative stress and renal dialysis.