A wide variety of foods has been tested using this method, with certain spices, berries and legumes rated highly in extensive tables once published by the United States Department of Agriculture (USDA), but withdrawn in 2012 since no correlation between test results and biological activity could be determined, stating that no physiological proof in vivo existed in support of the free-radical theory.
Values are expressed as the sum of the lipid soluble (e.g. carotenoid) and water-soluble (e.g. phenolic) antioxidant fractions (i.e., “total ORAC”) reported as in micromoles trolox equivalents (TE) per 100 gram sample, and are compared to assessments of total polyphenol content in the samples.
|FOOD||SERVING SIZE||ORAC, TROLOX EQUIV., ΜMOL PER 100 G|
|Small Red Bean||½ cup dried beans||13,727|
|Wild blueberry||1 cup||13,427|
|Red kidney bean||½ cup dried beans||13,259|
|Pinto bean||½ cup||11,864|
|Cranberry||1 cup raw (whole berries)||9,584|
|Blueberry||1 cup raw (cultivated berries)||9,019|
|Artichoke hearts||1 cup, cooked||7,904|
|Raw unprocessed Cocoa bean||1 oz||7.840|
|Blackberry||1 cup raw (cultivated berries)||7,701|
|Red Delicious apple||1 apple||5,900|
|Granny Smith apple||1 apple||5,381|
|Sweet cherry||1 cup||4,873|
|Black plum||1 plum||4,844|
|Russet potato||1, cooked||4,649|
|Black bean||½ cup dried beans||4,181|
|Gala apple||1 apple||3,903|
With nearly all vegetables, conventional boiling can reduce the ORAC value by up to 90%, while steaming retains more of the antioxidants.
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 of the intact food or its milled powder, others will evaluate ORAC units in fresh or frozen 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 compared to intact whole 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.