Researchers cast doubt on antioxidant tests

Are ORAC values, frequently cited on packaging as an indication of the antioxidant levels in a food or drink product, worth the labels they are written on? Maybe not, according to the results of a study by researchers at the University of Massachusetts' Department of Food Science.

They investigated whether simple assays such as ORAC and DPPH could accurately predict a food's antioxidant activity by testing the ability of a variety of antioxidant compounds to inhibit lipid oxidation in two model complex foods: ground beef and an oil-in-water emulsion.

They concluded: "Free-radical scavenging assays such as ORAC and DPPH were not able to consistently predict the ability of compounds to inhibit lipid oxidation in cooked ground beef. While simple one-dimensional free radical scavenging assays can be helpful in evaluating the antioxidant mechanisms of a compound, the data from these assays should not be used to imply that compounds with high free radical scavenging capacities are good antioxidants in food systems."

"ORAC and other measurements clearly only affect the individual ingredient being tested," said James Tonkin, principal at HealthyBrandBuilders, a California-based brand marketing and development firm. "They do not, however, test how a food or product will react in the human body, or whether it will maintain antioxidant protocols when ingested."

Source: Alamed J, et al. Relationships between Free Radical Scavenging and Antioxidant Activity in Foods. J Agric Food Chem 2009;57(7):2969-76.

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