Everyday metabolism, stress, and environmental pollutants cause cells in the body to produce Reactive Oxygen Species (ROS) molecules. ROS can, themselves, be oxygen free radicals. They can also form free radicals through interaction with biological molecules (proteins, DNA/RNA, and lipids).
ROS and free radicals are necessary intermediates in the body. However, too many oxygen free radicals are thought to play a role in cancer and aging. They also play a role in degenerative diseases, such as cardiovascular, Alzheimer's, and Parkinson's (1-5).
Oxygen free radicals and ROS are eliminated from the human body through enzymes (catalase, glutathione peroxidase, etc.). Their interaction with biological antioxidants (transferrin, ceruloplasmin, urate, etc.) also precipitates elimination. Nevertheless, these methods do not completely eliminate ALL these reactive intermediates from the body (6).
One way to help eliminate excess oxygen free radicals and ROS from the body is by consuming antioxidant rich foods. An inverse relation has been shown between the consumption of fruits and vegetables (antioxidant rich foods) and diseases (7-9). A drawback to these studies, though, was determining the exact antioxidant capacity of the food. Another drawback was determining what food component (flavenoids, vitamins, etc.) acts as an antioxidant (10-12).
A method was needed that could measure the antioxidant capacity of a substance. The Oxygen Radical Absorbance Capacity (ORAC) assay is such a method. This assay was first developed by Dr. Guohua Cao in 1993 (13) and was based upon the work of Glazer (14). Dr. Ron Prior, currently at the Arkansas Children's Nutrition Center, has modified and optimized the assay on BMG LABTECH's FLUOstar OPTIMA (15-17)