There is not necessarily a direct relationship between the antioxidant content of a food sample consumed and the subsequent antioxidant activity in the target cell.
This novel Antioxidant Food Table enables us to calculate total antioxidant content of complex diets, identify and rank potentially good sources of antioxidants, and provide the research community with comparable data on the relative antioxidant capacity of a wide range of foods. We have now performed a systematic measurement of the total antioxidant content of more than 3100 foods. Most assays for assessing total antioxidant capacity generally result in similar ranking of foods. A disadvantage of the FRAP assay is its inability to detect other small molecular weight thiols and sulfur containing molecules of e.g. This may be an advantage when using the FRAP assay, because glutathione is found in high concentrations in foods but it is degraded in the intestine and poorly absorbed by humans. Most other assays have higher reduction potentials and measures glutathione and other thiols. Thus, the FRAP assay does not measure glutathione. The FRAP assay directly measures antioxidants with a reduction potential below the reduction potential of the Fe 3+/Fe 2+ couple. Assay conditions, such as extraction solvents, were optimized regarding detection of both lipophilic and hydrophilic antioxidants. Most importantly, the modified FRAP assay is a simple, fast and inexpensive assay with little selectivity. Based on careful considerations (see Blomhoff 2005 and Halvorsen et al 2002 for discussion ) we chose to use a modified version of the FRAP assay by Benzie and Strain for total antioxidant analysis. the 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) equivalent antioxidant capacity (TEAC) assay, the ferric-reducing ability of plasma (FRAP) and the oxygen radical absorbance capacity assay (ORAC) assay. Several assays have been used to assess the total antioxidant content of foods, e.g. It is hypothesized that antioxidants originating from foods may work as antioxidants in their own right in vivo, as well as bring about beneficial health effects through other mechanisms, including acting as inducers of mechanisms related to antioxidant defense, longevity, cell maintenance and DNA repair.
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Antioxidants can eliminate free radicals and other reactive oxygen and nitrogen species, and these reactive species contribute to most chronic diseases. The large majority of these phytochemicals are redox active molecules and therefore defined as antioxidants. Most bioactive food constituents are derived from plants those so derived are collectively called phytochemicals. We suggest that both their numerous individual functions as well as their combined additive or synergistic effects are crucial to their health beneficial effects, thus a food-based research approach is likely to elucidate more health effects than those derived from each individual nutrient. Because of the complexity of this relationship, it is likely that a comprehensive understanding of the role of these bioactive food components is needed to assess the role of dietary plants in human health and disease development. Understanding the complex role of diet in such chronic diseases is challenging since a typical diet provides more than 25,000 bioactive food constituents, many of which may modify a multitude of processes that are related to these diseases. It is widely accepted that a plant-based diet with high intake of fruits, vegetables, and other nutrient-rich plant foods may reduce the risk of oxidative stress-related diseases.
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