It has become quite clear that free radicals play an important role in the development of many human diseases. The free radical connection to human diseases is so exciting that two new medical journals which deal solely with this subject have been created. It is now thought that once free radicals are made, they are the primary cause of certain human diseases involving many organs. This theory is supported by a multitude of data.
Free radicals cause damage to the nucleus of the cell and subsequently to the DNA. When certain segments of the DNA are affected, a malignant change occurs, altering the genetic ..ode and leading to cancer.15'16 It is thought that substances called antioxidants can protect against agents that cause cancer. Antioxidants work against (anti-) oxidation (the process in which oxygen reacts with another chemical) and thereby prevent the harmful effects of oxygen on tissue via free radical formation. These protective substances occur naturally in the body, and various nutritional supplements also act as antioxidants (see next section).
The preponderance of evidence suggests that free radicals damage the cells that line the inside of all blood vessels. Due to this initial injury, fats and fibrin and other elements of the blood ultimately form clots and block the arteries. It has also been shown that once a person sustains a heart attack, the injury that occurs within the first 12-24 hours is secondary to free radical damage. Therefore, antioxidants (also called free radical scavengers because they neutralize the free radicals) may have an important role not only in the prevention of cardiovascular disease but also at the time of an ongoing heart attack.