(ChemotherapyAdvisor) – A plant-based diet may prevent aggressive prostate cancer, with current smokers and younger men receiving the most benefit from increased flavonoid intake, results of a study presented during the 11th Annual AACR International Conference on Frontiers in Cancer Prevention Research has found.

Total flavonoid intake was inversely associated with prostate cancer aggressiveness, noted Susan E. Steck, PhD, MPH, RD, Arnold School of Public Health at the University of South Carolina, Columbia, SC, and colleagues.

Preclinical studies have found a chemopreventive effect of flavonoids on prostate cancer “via mechanisms related to anti-inflammation, induction of apoptosis, antioxidation, cell cycle regulation, and impairment of angiogenesis,” she noted. “However, few epidemiological studies have examined associations between flavonoid intake and prostate cancer in humans.”

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Data from patients newly diagnosed with prostate cancer from the North Carolina-Louisiana Prostate Cancer Project (PCaP) were assessed to determine the association between flavonoid intake and disease aggressiveness. Subjects completed a modified version of the National Cancer Institute Diet History Questionnaire, and flavonoid intake was calculated using the U.S. Department of Agriculture’s 2011 Database for the Flavonoid Content of Selected Foods.

The men, 920 African American and 977 European American, were classified as cases if their disease was highly aggressive (eg, Gleason sum ≥8, or PSA >20 ng/mL, or Gleason sum ≥7 and clinical stage T3c-T4c). Men with low and intermediate aggressive prostate cancer comprised the comparison group.

After adjusting for age, race, education, smoking status, and screening history, the highest tertile—vs the lowest tertile—of total flavonoid intake was inversely associated with prostate cancer aggressiveness history (OR 0.75; 95% CI 0.54–1.04).”

“Estimated odds of high aggressiveness prostate cancer with increasing flavonoid intake were reduced further by smoking and age, such that inverse associations were strongest in men <65 years of age (OR 0.62; 95% CI 0.40–0.98 and OR 0.67, 95% CI 0.42–1.06 for the middle and highest tertiles, respectively) and in current smokers (OR 0.25, 95% CI 0.11– 0.54 and OR 0.48, 95% CI 0.22–1.06 for the middle and highest tertiles, respectively),” they reported.

These results did not differ by race. Citrus juices, grapes, strawberries, onions, cooked greens, and tea were the primary contributors to total flavonoid intake. No individual subclass of flavonoids appeared to be protective independently, “suggesting that it is important to consume a variety of plant-based foods in the diet, rather than to focus on one specific type of flavonoid or flavonoid-rich food,” Dr. Steck.

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