Antioxidant properties in vitro and in vivo : realistic assessments of efficacy of plant extracts.

Abstract Diets or plant extracts (food supplements) rich in phytochemical antioxidants are able to reduce the incidence of non-communicable diseases such as cardiovascular diseases, diabetes, stroke and different types of cancer. Antioxidant properties are key criteria for the evaluation of the health-beneficial potential of a food, as a consequence, accurately assessing the antioxidant properties becomes critical. The various in vitro assay methods are important tools available for evaluating the antioxidant potential of foods. They are simple and can provide highly reproducible results for comparison of the different foods. A brief summary of the in vitro assay methods and in vivo commonly agreed key biomarkers and evidences is presented in this review. However, high antioxidant properties in vitro does not always lead to increased antioxidant values ex vivo or in vivo . Many factors can affect this, among them stability to stand the physicochemical and enzymatic degradation in the gastrointestinal tract, and bioavailability to the various tissues or organs of these phytochemicals are perhaps most important.