(HealthDayNews) - A diet rich in chocolate, wine, fruits and vegetables may help protect people from heart disease caused by air pollution, new research suggests.

The researchers found that elderly men were less likely to experience changes in heart function during heavy smog days if they ate foods loaded with flavonoids, an antioxidant found in plants.

For example, eating about 100 grams of blueberries (about three-quarters of a cup) every day might protect older men from smog-related heart disease, said lead researcher Jia Zhong, a doctoral student at the Harvard School of Public Health.

"We as individuals have no regular means to protect ourselves from air pollution," said Zhong's mentor, Dr. Andrea Baccarelli, an associate professor of environmental epigenetics at the Harvard School of Public Health. "Here we have a potential avenue where we can protect ourselves."

Smoggy air can reduce the heart's ability to vary its rhythm. Reduced heart rate variability has been linked to death from heart attacks and heart disease among older people, Zhong said.

"We were looking if there were any factors that could make the harm less significant," Zhong said.

The researchers landed on flavonoids, which are compounds in plants that provide their color. Flavonoids are well-known antioxidants -- substances that may prevent or delay some types of cell damage.

For their study, the researchers focused on 573 Boston-area elderly men taking part in an aging study. They compared clinical measurements taken of the men against air quality measures for their community, and had the men fill out diet questionnaires.