Featured Research

New Assay Can Improve Health Appeal of Antioxidant-based Products

January 22, 2016

The UNC Chapel Hill Nutrition Research Institute at the NC Research Campus developed a new and more reliable method to measure antioxidant capacity. The assay is available to companies investing in antioxidants to improve the health appeal of their products.  

 The global market for natural antioxidants is a multi-million dollar industry today, but by 2022, market reports predict it will be valued in the billions.

The reason?

Health-conscious consumers want the health benefits derived from naturally occurring bioactive compounds in fruits and vegetables like polyphenols and carotenoids because they provide antioxidant protection, meaning they stabilizing free radical molecules in the body that cause cellular damage. Research links their consumption to reduced risk for heart disease and some cancers, alleviation of diabetic symptoms, slowing of the aging process and improved cognition.


Steven Zeisel, MD, PhD

The challenge comes when consumers and, more often, government regulators demand proof that the antioxidants in a product provide the health benefits promised. The UNC Chapel Hill Nutrition Research Institute (NRI) at the NC Research Campus (NCRC) in Kannapolis, NC developed an assay that measures activation of antioxidant response elements (AREs), a system in the human body that turns on genes that in turn produce enzymes responsible for boosting cellular protection against free radical damage. By working with the NRI to apply the assay to products, companies gain a new approach to evaluate the antioxidant activity of their products that can give them scientific evidence to share with their consumers and inquiring regulators.

“In the past,” said Steven Zeisel, MD, PhD, UNC NRI director, “we recognized antioxidants as chemicals that can tie up damaging free radicals or by their chemical structure, but these assays did not always detect molecules that can strengthen our internal protection systems that protect our cells from oxygen and UV damage. Our assay does.”

Assay Results 


A new assay identified lettuce varieiteis as an activator of AREs. Photo credit Wikipedia.

The first study using the assay was published in the Journal of Nutrition and conducted in partnership with the Dole Nutrition Institute (DNI), the NCRC-based education and research arm of Dole Food Company. The findings revealed that out of 134 extracts taken from the peels and flesh of fruits and vegetables, 107 activated antioxidant response elements (AREs) in human cells.  Some of the most effective activators included 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 compared to the classic antioxidant assays, total phenolics and ORAC (Oxygen Radical Absorbance Capacity scores).  Scientists found that some fruits and vegetables that measured low in ORAC or total phenolics were high in their ability to activate AREs.

Insufficient Models of Measurement

In 2010, the US Department of Agriculture denounced the use of ORAC values as a measurement “due to mounting evidence that the values indicating antioxidant capacity have no relevance to the effects of specific bioactive compounds, including polyphenols on human health.” Despite the insufficiency of ORAC values, they are still used for antioxidant content measurement along with total phenolics, a method that identifies polyphenol structures in food but not how those structures impact human health.


Nick Gillitt

“This suggests that traditional measurements of antioxidant capacity do not give the full picture,” commented Nicholas Gillitt, PhD, vice president of nutrition research for Dole Food Company and DNI director. “For Dole, these findings have opened up an entirely new line of research that will help us better understand the health benefits of our products.”

A New View of Antioxidants

Zeisel is working with companies to test their products for antioxidant capacity, and additional clinical trials are underway to develop the application of the assay further.

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

Learn more about the UNC Nutrition Research Institute and the Dole Nutrition Research Institute.

Read more featured research. View scientific journal articles.



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