Oxygen Radical Absorbance Capacity - Comparisons of ORAC Values

Comparisons of ORAC Values

The United States Department of Agriculture, previously a publisher of ORAC data, withdrew its web publication of ORAC values for common American foods in 2012 due to absence of scientific evidence that ORAC has any biological significance.

When comparing ORAC data, care must be taken to ensure the units and food being compared are similar. Some evaluations will compare ORAC units per gram of dry weight, others will evaluate ORAC units in wet weight and still others will look at ORAC units per serving. Under each evaluation, different foods can appear to have higher ORAC values. For example, although a raisin has no more antioxidant potential than the grape from which it was dried, raisins will appear to have a higher ORAC value per gram of wet weight than grapes due to their reduced water content. Likewise, the large water content in watermelon can make it appear as though this fruit is low in ORAC. Similarly, the typical quantity of food used should be considered; herbs and spices may be high in ORAC, but are applied in much smaller quantities than for other foods.

Numerous health food and beverage companies and marketers have erroneously capitalized on the ORAC rating by promoting products claimed to be "high in ORAC". As most of these ORAC values have not been independently validated or subjected to peer review for publication in scientific literature, they remain unconfirmed, are not scientifically credible, and may mislead consumers.