A study published in The American Journal of Clinical Nutrition shows that flavonoids may decrease the risk for ovarian cancer.
The researchers followed 171,940 Nurses' Health Study and Nurses' Health Study II participants to examine associations between intakes of total flavonoids and their subclasses (flavanones, flavonols, anthocyanins, flavan-3-ols, flavones, and polymeric flavonoids) and risk of ovarian cancer by using Cox proportional hazards models. Intake was calculated from validated food-frequency questionnaires collected every four years.
During 16–22 years of follow-up, 723 cases of ovarian cancer were confirmed through medical records. In pooled multivariate-adjusted analyses, total flavonoids were not statistically significantly associated with ovarian cancer risk. However, participants in the highest quintiles of flavonol and flavanone intakes had modestly lower risk of ovarian cancer than that of participants in the lowest quintile. Two cups of black tea per day, for instance, lowered a woman's risk by an average of 31%.
Flavonols are found in cruciferous vegetables like broccoli and kale, in beverages like tea and red wine, and in fruits like apples and grapes. Flavanones are most often found in citrus fruits, such as oranges, lemons, and grapefruits.
The researchers concluded that "higher intakes of flavonols and flavanones as well as black tea consumption may be associated with lower risk of ovarian cancer." They did note that additional prospective studies are required to confirm these findings.