Nutritional Pearls: Ovarian Cancer
Michelle is a 55-year-old woman hearing that many of her friends are getting diagnosed with ovarian cancer. She wants to know if there are any nutritional supplements or dietary changes she should make to help prevent a future diagnosis.
How would you advise her?
What is the correct answer?
(Answer and discussion on next page)
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Answer: Drinking black tea may reduce your risk of ovarian cancer.
Given the difficulty of diagnosis, ovarian cancer may well be one of the most-feared cancers. Only 15% of all ovarian cancers are diagnosed at an early stage.1 The 5-year relative survival rate for all types and stages of ovarian cancer is 44%; women diagnosed younger than 65 do better than older women.1
A majority, or 60%, of ovarian cancers are diagnosed at stage 3; only 27.4% of these women live for 5 years or more. By comparison, 61% of breast cancer diagnoses are made at stage 1, when the cancer is still localized, and 98.5% of those women survive for 5 years or more.
The Research
We do know that while about 10% of cancers are caused by a gene mutation, but 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, as well as many cancers. An international group of researchers recently made use of data gathered through 2 large-scale, long-term studies of women, the Nurses' Health Study and the Nurses' Health Study II,2 to assess whether there is a link between a woman's intake of flavonoids and risk of ovarian cancer.
After analyzing the food frequency questionnaires gathered every 4 years from 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 that supply the most significant amounts of those antioxidants. Both the absolute intake and the dietary intake were then compared between women who developed epithelial ovarian cancer and those who did not.
The intake of total flavonoids was not significantly related to risk of ovarian cancer. However, 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 2 largest sources of flavonols, while citrus fruit and citrus juices (including grapefruit juice) were the largest sources of flavanones.
What’s the “Take Home”?
There is even more reason to suggest that your patients 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. Recommend keeping a batch of iced tea in the refrigerator and drink that instead of soda. Even if it is sweetened tea, they still get far less sugar than in any sugar-sweetened soda and the boost in antioxidants can be a key component in lowering the risk of cancer.
References:
- American Cancer Society. Survival rates for ovarian cancer, by stage. 2014 Aug 11. www.cancer.org/cancer/ovariancancer/detailedguide/ovarian-cancer-survival-rates. Accessed September 16, 2014.
- Cassidy A, Huang T, Rice M, et al. Intake of dietary flavonoids and risk of epithelial ovarian cancer. Am J Clin Nutr. 2014 Oct [epub ahead of print] doi: 10.394S/ajcn.114.088708