Juice could ward off cancer in smokers.

Although citrus products confer numerous health benefits to the population as a whole, a new study shows that citrus is a particularly wise dietary choice for smokers. According to researchers at the University of Hawaii's Cancer Research Center in Honolulu, drinking grapefruit juice every day could reduce the risk of developing cancer from smoking.

The Hawaiian group, led by Loic Le Marchand, conducted a study on 49 smokers of Asian ancestry. The volunteers smoked on average 10 cigarettes a day, were not taking any medications or dietary supplements, and generally were in good health.

The researchers put the smokers on a special diet for 6 weeks and analyzed their urine samples throughout that time. Partway through the study, the researchers asked the smokers to drink a 6-ounce glass of grapefruit juice three tunes a day for a week.

Soon thereafter, concentrations of naringenin--a flavonoid in grapefruit juice--increased significantly in the smokers' urine. The flavonoid concentrations dropped back down after the smokers stopped drinking the juice. Previous studies have shown that naringenin can have anticancer effects.

Urine analyses revealed that the spike in naringenin was associated with a significant decrease in the activity of the liver enzyme known as CYP1A2. That substance is known to activate certain cancer-causing chemicals that are present in tobacco smoke.

The team cautions that the results are preliminary and that, because of genetic differences, people absorb varying amounts of naringenin.