Prostate cancer is the most common cancer and the second leading cause of cancer death among men in the United States. Nearly 165,000 men in the United States will be diagnosed with the disease this year. Now comes a study, published in Complementary Therapies in Medicine, that suggests dietary flavonoid intake may reduce the risk of developing prostate cancer.
Flavonoids comprise a large class of plant-based dietary compounds – broadly referred to as phytochemicals – that contribute to the appearance, fragrance, and flavor of many fruits and vegetables. Subclasses of flavonoids include flavonols, catechins, flavanols, flavones, flavanones, and anthocyanidins.
Data from large, population-based studies suggest that diets rich in fruits, vegetables, whole grains, and healthy oils, may reduce the risk of developing prostate cancer. A common element of these foods is their high flavonoid content.
The researchers conducted a case-control study among men living in southern Italy. “We aimed to investigate the impact of specific dietary habits and prostate cancer,” says Giorgio Russo, MD, PhD, a physician at the Urology Clinic of the University of Catania and one of the authors of the study. In particular, they wanted to see whether flavonoids reduced prostate cancer risk.
Participants in the study included 118 men with prostate cancer (cases) and 222 men without the disease (controls). The cases and controls were matched by age, whether they smoked, and body mass index, or BMI, a proxy for body fatness. Body fatness strongly influences prostate cancer risk.
Each of the men completed a food frequency questionnaire that asked questions about what types and amounts of flavonoid-containing foods they regularly ate. Information about flavonoid content in the foods was derived from the Phenol-Explorer database.
Statistical analysis revealed that there were no significant differences in overall flavonoid intake between the men who had prostate cancer and those who did not. However, the researchers did observe differences in intake of the individual flavonoid subclasses among the two groups. Specifically, intake of flavonols and catechins was much higher among the men who did not have cancer.
The study’s findings suggest that high intake of dietary flavonoids, especially flavonols and catechins, may be linked with reduced risk of developing prostate cancer. “These findings are extremely important,” says Russo. “Prostate cancer is the most commonly diagnosed tumor in men, and we don’t really know how to prevent it.” However, only one cohort study has examined these factors directly.
Flavonoids like flavonols and catechins are abundant in the human diet. “Flavonols and catechins are typically present in tea, one of the most widely consumed beverages in the world,” says Russo. “These molecules may play a role in the prevention of prostate cancer by inducing cell growth arrest and apoptosis.” Apoptosis is a type of programmed cell death. Other sources of flavonols and catechins include apples, grapes, and berries.
Future research will investigate the role of the Mediterranean diet in preventing prostate cancer and will analyze the effects of the diet on prostate cancer tissue.