For years, claims about dietary antioxidants were based on two laboratory methods: oxygen radical absorbance capacity (ORAC) and total phenolics (TP). Although these measurements describe antioxidant capacities of foods and food ingredients, their use in marketing claims were misleading and confusing.

In theory, the higher the value of either ORAC or TP, the greater the antioxidant capacity and thus the greater the health and wellness benefit. Today, with a better understanding of how antioxidants work in the body, ORAC and TP values have lost their credence and, in fact, are shunned by FDA and the Federal Trade Commission, which regulates advertising claims.

This is why the term “superfood” has come to be associated with antioxidant-rich foods. For example, Kuli Kuli Foods, Oakland, CA, uses moringa, a leafy green, nutrient-dense vegetable to make its Moringa Superfood bars.

“Most consumers don’t know what ORAC means anyway, but they do know that antioxidants are good for them,” said Lisa Curtis, CEO and one of the company’s founders. “Moringa is very high in antioxidants, and we call it out as ‘Moringa Superfood’ on our bars, which is an indirect way of flagging that it’s a concentrated source of antioxidants.”

Just how super are moringa and other foods with antioxidant properties? Scientists at the University of North Carolina (UNC) Chapel Hill Nutrition Research Institute (NRI) at the NC Research Campus (NCRC), believe they have developed an assay that quantifies the biological effects of antioxidants.

These researchers learned that activation of antioxidant response elements (AREs), a system in the human body that turns on genes that, in turn, will produce enzymes responsible for boosting cellular protection against free radical damage. Thus, AREs mediate against cell damage. ORAC and TP assays do not measure capacity to activate AREs, but this new assay does.

Applying the assay to food products will help companies evaluate the antioxidant activity of their goods, giving them scientific evidence to share with consumers and regulators, according to Steven Zeisel, MD, PhD, UNC NRI director.

The first study using the assay was conducted in partnership with the Dole Nutrition Institute (DNI), the NCRC-based education and research arm of Dole Food, Thousand Oaks, CA. Results were published in the September 2015 edition of Journal of Nutrition.

The findings revealed that out of 134 extracts of fruits and vegetables, 107 activated AREs in human cells. Some of the most effective activators include avocado peel, carrot, red pear peel, pineapple, lemon flesh, green pear peel, Red Delicious apple peel, spinach and a variety of lettuces.

Each fruit and vegetable in the study was also evaluated for ORAC and TP. Scientists found that some fruits and vegetables that measured low in ORAC or TP were high in their ability to activate AREs.

“Our assay changes how we can recognize constituents of fruits and vegetables that improve our internal antioxidant defenses,” Dr. Zeisel said. “We are interested in using our novel antioxidant assay to help companies identify the components of their products that actually do this.”