In all oxygen consuming cells, metabolism and oxidative stress generate several intermediates and byproducts that are collectively known as reactive oxygen species (ROS). ROS are necessary intermediates in the human body, but they are also involved in the aging process and in the development of many degenerative diseases, including cancer, heart disease, Alzheimer's and Parkinson's. Herein we describe the determination of the antioxidant capacity of different fruit juices using the ORAC assay; a standardized method that uses Trolox®, a water-soluble analogue of vitamin E, as a standard substance more