Many diseases are associated with Oxidative Stress (OS) Therefore, in developed countries, many people take antioxidant supplementation (52% in the US). The "Identify and treat" approach advocates supplementing antioxidants to people under oxidative stress. This requires quantitation of OS. which is usually based on the steady state concentration of a biomarker. Assay Kits are commercially available and are likely to assist promotion of antioxidants. We think that the term OS is ill-defined because it dependent on the method used to quantitate it. Recently, we demonstrated that oxidative stress, as assayed by a single test, cannot be used as a diagnostic tool. We propose quantitating OS and ranking antioxidants on the basis of kinetic studies, specifically on the basis of the lag preceding serum lipid peroxidation ex-vivo. We also give examples of studies conducted this way that yield reasonable results. We wish to discuss ways to promote the influence of the results of scientific research on the consumption of food supplements.