Powerful energy booster lurks in produce bin

Researchers at the University of South Carolina have found that quercetin, a compound found in fruits and vegetables, gives a sustained energy boost that's better than a jolt of caffeine.

Quercetin won't replace the health benefits of exercise, said Mark Davis, the lead author of a study conducted by USC's Arnold School of Public Health and reported online last month by the International Journal of Sports Nutrition and Exercise Metabolism. But the fatigue-fighting elements in the compound — found in the skins of red apples, red onions, berries and grapes — might be enough to help people get off the couch and start exercising.

"It's a nutritional strategy to reduce fatigue and improve endurance," Davis said. "There's still a lot of work to be done, but we're encouraged by the initial study."

Davis' study, which followed 12 healthy college-age students who were not athletes, found that after taking quercetin for seven days, participants had a 13.2 percent increase in endurance and a 3.9 percent increase in maximal oxygen capacity, an important measure of fitness.

For the study, funded in part by the U.S. Department of Defense, 12 participants were randomly assigned to one of two groups. Half were given 1,000 milligrams of quercetin per day in Tang.

The other half drank Tang with a placebo. The subjects then rode stationary bikes to the point of fatigue. The participants then received the opposite treatment for another seven days.

A person would have to eat about 100 apples to get 1,000 milligrams of quercetin, Davis said, so they can't get enough to boost energy from diet alone.

His early research on quercetin, work he conducted before studying the impact on humans, suggests that quercetin may increase the mitochondria in brain and muscle cells, Davis said.

He likened the mitochondria to the "powerhouse of the cell," producing most of its energy. Mitochondria in the brain and muscles also are believed to be fundamentally important in battling age-related dementia, obesity, diabetes and cardiovascular dysfunction, he said.

The study indicates to researchers that quercetin works to reduce fatigue, Davis said. The next steps are learning more about how it works.

According to the American Cancer Society, quercetin appears to have anti-inflammatory and antioxidant properties and has been promoted as being effective against a wide variety of diseases, including cancer.

While some early laboratory results appear promising, the society states, there is no reliable clinical evidence that quercetin can prevent or treat cancer in humans.

Davis and his team have recently been awarded a grant to study quercetin's effects on colon cancer. Another grant to look at its effects on breast cancer is in the works.

Davis, who said he and some his graduate students take quercetin supplements to boost their own endurance, said the compound likely has great potential to help with diseases and age-related problems. "Human studies are only in their infancy," he said.

Reach Diane Knich at 937-5491 or dknich@postand courier.com.