Free radicals (or reactive oxygen species) are highly reactive molecules, either endogenously created in the body during normal metabolic processes or exogenously introduced by the environment. Although essential to life, oxygen is the main source of these potentially damaging free radicals. Free radicals are unstable and reactive compounds since they contain ‘extra’ energy (often in the form of an unpaired electron in the outer shell of the molecule). To reduce this energy load, free radicals react with cells, tissue or other molecules in the body, and in the process, interfere with the ability of cells or organs to function properly.
Free radicals can have several exogenous sources. Examples of environmental sources of free radicals include exposure to ultraviolet (solar) radiation, cigarette smoke, air pollution, ozone, heavy metals, gamma or X-ray radiation, and excessive use of alcohol.
Free radicals are believed to play a role in a number of different disease conditions, including the aging process, cardiovascular diseases, several inflammatory diseases and even some forms of cancer. Reducing the exposure to free radicals and sufficient intake of antioxidant nutrients may help to reduce the risk of free radical-related health problems.