Drinking black tea may reduce your risk of ovarian cancer

Ovarian cancer may well be the most-feared diagnosis for women, even more than breast cancer. Why? Because the vast majority of ovarian cancers are not detected until they are quite advanced: only 15% of all ovarian cancer patients are diagnosed at an early stage of the disease (ovariancancer.org). While about 44% of all women diagnosed with ovarian cancer survive for at least five years after diagnosis, that statistic is for all women diagnosed at all stages.

Over 60% of ovarian cancers are diagnosed at Stage III: metastatic cancer. Only 27.4% of women at Stage III when diagnosed live for 5 years or more. By comparison, 61% of breast cancers are diagnosed at Stage I, when the cancer is still localized, and 98.5% of those women survive for 5 years or more (seer.cancer.gov).

We don't know what exactly causes ovarian cancer. We do know that while about 10% of cancers are caused by a faulty gene, like many cancers diet plays a role. Recently antioxidants, particularly the subtype known as flavonoids, have come under scrutiny for their role in preventing heart disease, diabetes, and Alzheimer's disease, not to mention cancers. An international group of researchers recently made use of data gathered through two large-scale, long-term studies of women, the Nurses' Health Study and the Nurses' Health Study II (AJCN 2014; ahead of print), to assess what link there might be between a woman's intake of flavonoids, a group of subtypes of antioxidants, and their risk of ovarian cancer.

After analyzing the food-frequency questionnaires gathered every four years for over 171,000 women, the researchers could group the women's intake of the different antioxidant subtypes into levels of intake by both their absolute intake of the antioxidant as well as by the amounts of the foods which supply the most significant amounts of those antioxidants. Both the absolute intake and the dietary intake were then compared between those women who developed epithelial ovarian cancer and those who did not.

Although the intake of total flavonoids was not significantly related to risk of ovarian cancer, when the researchers looked at flavonoid subtypes the outcome was rather different. Those who consumed the very highest amount of flavonols and flavanones had a much lower risk of ovarian cancer than those who consumed the least: as much as 28% lower risk. Other subtypes of flavonoids were not associated with a change in risk.

What were the foods most frequently consumed that accounted for the nurses' flavonoid intake? Black tea and onions were the two largest sources of flavonols, while citrus fruit and citrus juices (including grapefruit juice) were the largest sources of flavanones.

What this means for you

Even more reason to switch from sodas to teas. Hot or cold doesn't matter, but it appears that even powdered teas, if made from tea leaves, contain some flavonols. In the Summer, keep a batch of iced tea in the refrigerator and drink that instead of soda. Even if you add sweetener, you'll still get far less sugar than you would in a sugar-sweetened soda, and you'll help reduce your risk of ovarian (and other) cancers.

First posted: September 10, 2014