Physiological Context
Although research in vitro indicates polyphenols are good antioxidants and probably influence the ORAC value, antioxidant effects in vivo are probably negligible or absent. By non-antioxidant mechanisms still undefined, flavonoids and other polyphenols may reduce the risk of cardiovascular disease and cancer.
As interpreted by the Linus Pauling Institute, EFSA and the USDA, dietary polyphenols have little or no direct antioxidant food value following digestion. Not like controlled test tube conditions, the fate of polyphenols in vivo shows they are poorly conserved (less than 5%), with most of what is absorbed existing as chemically modified metabolites destined for rapid excretion.
The increase in antioxidant capacity of blood seen after the consumption of polyphenol-rich (ORAC-rich) foods is not caused directly by the polyphenols, but most likely results from increased uric acid levels derived from metabolism of flavonoids. According to Frei, "we can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them."
Read more about this topic: Oxygen Radical Absorbance Capacity
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