WASHINGTON — Snack foods such as popcorn and breakfast cereals contain large amounts of healthful antioxidants called polyphenols, according to scientists who spoke Aug. 18 at the 238th National Meeting of the American Chemical Society in Washington.

"We found that, in fact, whole grain products have comparable antioxidants per gram to fruits and vegetables," said Joe Vinson, a chemist at the University of Scranton in Pennsylvania. "This is the first study to examine total phenol antioxidants in breakfast cereals and snacks, whereas previous studies have measured free antioxidants in the products."

Polyphenols are found in such items as fruit, vegetables, chocolate, wine, coffee and tea. They are known for their potential role in reducing the risk of heart disease, cancer and other diseases. Whole grain cereals have been known more for their fiber content.

"Early researchers thought the fiber was the active ingredient for these benefits in whole grains, the reason why they may reduce the risk of cancer and coronary heart disease," Dr. Vinson said. "But recently, polyphenols emerged as potentially more important. Breakfast cereals, pasta, crackers and salty snacks constitute over 66% of whole grain intake in the U.S. diet."

Whole grain cereal made with wheat contained the most antioxidants, and it was followed in descending order by corn, oats and rice cereals, Dr. Vinson said. Raisin bran had the highest amount of antioxidants per serving, primarily because of the raisins. Bran cereals made from wheat do not have more antioxidants than wheat cereals, but they do have more fiber.

Whole grain flours are high in antioxidants, according to the study, which was funded internally by the University of Scranton. Whole grain snacks have slightly lower levels of antioxidants than cereals with popcorn having the highest level of antioxidants among all snacks. The amount of antioxidants in each class of cold cereal varies.