Oxidative stress is a pathological state that arises when free radicals (collectively known of as reactive oxygen species or ROS) chemically interact with and damage biological molecules. Oxidative stress research has largely focused on the role and effects of antioxidants in protecting these molecules from damage.

Antioxidants in disease prevention

While studies show that that beta carotene, for example, has a pro-oxidative effect in the lungs of smokers, other epidemiological research has demonstrated an inverse relationship between levels of established antioxidants such as vitamin E and C and disease states such as cancer and cardiovascular disease. The levels of these vitamins are also inversely associated with mortality caused by these diseases.Antioxidants may be used in disease prevention but the extent of their benefits is not fully understood. The use of antioxidants to treat disease states induced by oxidative stress is controversial.

Antioxidant source

Most antioxidants are obtained from diet but they can also be taken as supplements in the form of capsules or tablets.

Most fresh fruits and vegetables provide a natural source of antioxidants. Large population studies have shown that regular intake of adequate portions of fruits and vegetables has been seen to protect against numerous cancers, heart diseases and other disorders.

Apart from vitamins such as vitamins E and C, examples of other antioxidants include minerals, resveratrol, beta carotene (a precursor form of vitamin A), selenium, green tea and jiaogulan.

Current antioxidant treatment

Several antioxidants are currently used to treat diseases.

For example, antioxidants may be useful in treating patients after a stroke to protect the nerves and brain cells from oxidative damage and lipid peroxidation. Agents such as superoxide dismutase mimetics, sodium thiopental and propofol can be used to treat reperfusion injury that occurs after traumatic brain injury.

These agents prevent neural cell death. Individuals with neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease also benefit to a certain extent from the use of antioxidants.