Vinson and Michael Coco, Jr., a chemistry student at the university, analyzed four commercial brands of popcorn, including two air-popped and two microwave varieties.
They evaluated antioxidants known as polyphenols. These compounds are found in a wide variety of plants. Antioxidants undo the damage that can be done by unstable molecules known as ''free radicals."
"Everyone knows plant foods have antioxidants," Vinson tells WebMD. "But nobody has even looked at what is in popcorn with respect to these compounds."
Vinson and Coco ground up the hull and the ''fluffy stuff," Vinson says, and checked the polyphenol levels.
Most of the polyphenols -- about 90% -- were in the hull, Vinson says.
The four brands tested had slightly different serving sizes, from a little under an ounce to a little over. The antioxidants per serving ranged from about 242-363 milligrams (mg).
In comparison, they found that a serving of many fruits has about 160 mg of polyphenols.
Popcorn's polyphenols are not as diluted with water as those are in fruit, Vinson says."Popcorn starts out about 15% water and ends up a couple percent."
He calls popcorn "a wonderful high-fiber snack," but like other experts, he warns that adding too much butter and other oil can quickly ruin popcorn's healthy image. He presented the study, which was partially funded by Weaver Popcorn Company, today in San Diego at the American Chemical Society's annual meeting.
Antioxidants in Popcorn: Study Details
The study is a good first step, but it wasn't designed to measure health benefits, says Jeffrey B. Blumberg, PhD, professor of nutrition at Tufts University and senior scientist and director of Tufts' Antioxidants Research Laboratory.
The next step is to figure out how much of popcorn's polyphenols get out of the hull and into your gut, Blumberg says.
Blumberg is studying polyphenols and other substances in whole grains. He is evaluating how much of the compounds, and which ones, get into the blood. That study is supported by the U.S. Department of Agriculture and cereal maker Kellogg's.
"We already know whole grains are good for you," Blumberg says. What scientists now need to figure out, he tells WebMD, are which components are really important in improving health.
The information could be useful for people who grow crops, he says. They could then grow the crops to produce whole grain with more of the compounds found to be healthiest.
The Vinson study does suggest that popcorn is not bad as a snack, says Kantha Shelke, PhD, a Chicago food chemist and spokeswoman for the Institute of Food Technologists.
"Popcorn is a whole grain," she says. "It's minimally processed." But more information is needed, she says, on what amount of popcorn's antioxidants actually go to work in your body.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.