Food and nutrition scientist sheds light on dietary antioxidant research

Ock Chun
Ock Chun

Scientific results on antioxidants and their effect on chronic disease are mixed at best. In theory, antioxidants disable damaging chemical compounds called free radicals that contribute to chronic diseases such as cardiovascular disease and some cancers. But numerous studies suggest that, by themselves, these free-radical-counterinsurgents don’t do much to relieve chronic disease.

What antioxidants can achieve together, however, is a different story. While the impact of individual antioxidants might come up short, more promising results may come from what nutrition scientists call total antioxidant capacity (TAC). TAC measures the cumulative effect of antioxidants on free radicals and may hold clues to fighting chronic disease.

Enter Ock Chun, associate professor in the Department of Nutritional Sciences. For seven years, Chun has been establishing critical baseline data to help identify the links between TAC and chronic disease. Chun established the first database that records the TAC of foods in the US diet and has helped to identify novel correlations between TAC and cardiovascular disease, prostate cancer and more.

Chun received her degrees from the Seoul National University in South Korea: a BS in food and nutrition, a master of public health (MPH) and a PhD in public health. She first came to the United States in 2002 as a postdoctoral fellow at Cornell University. In 2003, she became a research associate in human nutrition at Michigan State University and was appointed professor there in 2006. After a brief stint as an assistant professor at East Carolina University, she came to UConn in 2008 as an assistant professor in the Department of Nutritional Sciences.

Despite a diverse career, Chun says that it was ultimately UConn where she wanted to end up. “In the long term, this is the best place for me. My whole family is around this area. I feel much happier here. I think UConn, and especially this department—their support is great.”

Once at UConn, Chun began gathering baseline data on TAC. Her first project was to create a database that documents the TAC of various foods in the average US diet, something that had never been done before. This investigative protocol was validated by establishing relationships between estimated dietary antioxidant intakes of US adults and the concentrations of antioxidants in blood and urine.

She assayed dozens of foods and identified the top food sources based on TAC. They were, in order: tea, antioxidant supplements, orange juice, wine, beer, bananas, blueberries, oranges, and apples.

Of course, that medley of fruits, vegetables and drink isn’t what US adults eat every day on average, so Chun’s next step was to estimate the dietary TAC of the average US adult. She reached some interesting results. Only 21 percent of adults in this country drink tea, but green tea makes up 28 percent of our dietary TAC because it’s so rich in antioxidants. 80 percent of US adults consume fruits and fruit juices, but these contribute only 17 percent to the TAC of our diet.

Before interpreting these results, it’s important to note that TAC is only a convenient dietary concept. In theory, TAC reflects the synergistic effect of antioxidants on free radicals. As some scientists explain, antioxidants can “talk to each other” to build a stronger cooperative network that can more effectively disable free radicals. But there isn’t one foolproof way to measure TAC. Instead, by using multiple techniques, scientists can draw correlations between TAC and markers of chronic disease.

That was Chun’s ultimate research goal: to understand the impact of TAC on chronic disease. For example, in 2013, one study co-authored by Chun found that a diet with high levels of TAC was highly correlated with lower incidence of cardiovascular disease.

Her most recent research interest has been to study the relationships between TAC and prostate cancer. The verdict is still out on whether antioxidants can help to reduce prostate cancer. Scientific results so far are inconsistent on the subject, but until recently, there hasn’t been much prostate cancer research focused on TAC. In a population-based study in 2013, Chun’s results suggested that greater TAC is associated with less-aggressive prostate cancer.

Chun wants to learn more about the racial and ethnic differences between antioxidant intake and risk of chronic disease, but she says that it’s difficult to find sufficient data on the diet of African Americans. The solution, she says, might be to look at multi-ethnic datasets, comparing data on TAC intake and prostate cancer rates among Asian Americans, Hispanic Americans, African Americans and Caucasian Americans.

The racial and ethnic variables Chun studies in relation to diet are just a glimpse of the broad perspective she has when it comes to food and nutrition. She says that her research is about making sense of all the individual variables involved in nutrition and health: diet, exercise, age, gender, socioeconomic class, etc. By understanding how each of these variables affect someone’s risk or aggressiveness of chronic disease, more effective prevention measures can be established that target individuals and ultimately increase their long-term health.

This broad perspective is something Chun says she learned in her public health education in South Korea. She says her nutrition studies alone weren’t giving her the whole picture.

“I thought that I more wanted to approach nutrition in other aspects and holistically. It’s why I decided to study public health.” It was there that she learned nutrition is very tightly connected to social demographic factors and that there aren’t simple solutions for certain socioeconomic groups like the extreme poor. “It was really helpful in my long-term research.”

Chun is also an expert on research design, which comes in handy when she designs new studies. While inconsistencies still abound in antioxidant research—it’s not clear that eating more TAC-rich foods is a sure-fire way to reduce the risk of chronic disease, for example—Chun hopes she can continue to design sound studies that make clear the specific links between TAC and its impact on chronic disease so that her research can contribute to effective prevention techniques.

By Michael Clausen