According to the Los Angeles County Department of Health, ovarian is the third leading cause of death behind (1) lung and (2) breast. A new study assessed the benefit of flavonoids, which are present in black tea, for the prevention of ovarian cancer. The study was published last August in the American Journal of Clinical Nutrition by an international team of researchers.
Flavonoids have been shown to have a wide range of biological and pharmacological activities in in laboratory studies. They include anti-allergic, anti-inflammatory, antioxidant, antibacterial, antifungal, antiviral, anti-cancer, and anti-diarrheal properties. The study authors note that the impact of various dietary flavonoid subclasses on the risk of ovarian cancer is unclear, and limited studies in the medical literal have focused on only a few of the different types of flavonoids.
The investigators conducted a study to assess associations between regular flavonoid intake and the risk of ovarian cancer. The study group comprised 171,940 women enrolled in the Nurses’ Health Study and Nurses’ Health Study II. The researchers examined associations between ingestion of total flavonoids and their subclasses (flavanones, flavonols, anthocyanins, flavan-3-ols, flavones, and polymeric flavonoids) and the risk of ovarian cancer. Flavonoid intaked was calculated from validated food-frequency questionnaires collected every four years.
The researchers found that during 16–22 years of follow-up, 723 ovarian cancer cases were confirmed via medical records. Statistical analysis revealed that, overall, total flavonoids were not statistically significantly associated with ovarian cancer risk. However, women who were in the top 20% of flavonol and flavanone intakes had a somewhat lower risk of ovarian cancer than did participants in the lowest 20%. The association for flavanone intake was stronger for serous invasive and poorly differentiated tumors, compared to nonserous and less-aggressive tumors. Intakes of other subclasses were not significantly associated with risk. In food-based analyses, which were used to compare women who consumed more than 1 cup of black tea to those who consumed less than 1 cup of black tea per day, the women who consumed more than one cup had a32% decreased risk of ovarian cancer.
The authors concluded that higher intake of flavonoids as well as black tea consumption may be associated with lower risk of ovarian cancer. They recommended that further prospective (forward-looking) studies should be conducted to confirm their findings.
The researchers are affiliated with: Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, United Kingdom; the Department of Epidemiology, Harvard School of Public Health, Boston, MA; and the Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA.