Measurement of the antioxidant status of dietary constituents, low density lipoproteins and plasma.

There is a considerable interest in antioxidants as bioactive components of food and as nutritional agents with a role in the maintenance of health and in disease prevention. There are situations in which knowledge of the individual levels of specific antioxidant components might be less useful than the total antioxidant potency of the medium concerned, the total antioxidant activity being determined by the combined reducing activities of its constituents. Such situations might be in the understanding of the structure-activity relationships of pure antioxidant compounds, in the determination of the antioxidant contributions of specific dietary components and how this relates to the antioxidant composition and activities of the individual constituents, and in the study of decreases in plasma antioxidant activity in individuals under oxidative stress in specific disease states. This article describes the application of the ABTS radical cation method to the measurement of the total antioxidant activity in order to address these questions.