Free radicals are molecules or atoms that has single unpaired electron. As an organism aging, along with it, the body accumulate free radicals over time. However our body system have a complicated system of multiple antioxidants. A list might include: Gluthothione, Vitamin C, Vitamin E, and enzymes such as catalase, superoxide dismutase, and several forms of peroxidases.
These antioxidants come from the foods we eat. If you are healthy your body can manufacture some antioxidants like SOD and Gluthothione. However, it is essential to add an antioxidant supplement to aid your body in providing sufficient amounts of antioxidant power against free radicals.
To get more information about free radicals and the damage that it can cause, you can watch the video below.