"don't be loyal to tea,
Tea Tippling Linked to Lower Ovarian Cancer Risk
STOCKHOLM, Sweden, Dec. 12 - Middle-age women who drink two or more cups of green or black tea every day may reduce their risk for invasive epithelial ovarian cancer by almost half, epidemiologists here reported.
In a prospective population-based study, Karolinska Institute researchers found a dose-response relationship between the amount of tea a woman consumed and her risk for ovarian cancer, after controlling for potential confounders (P for trend, .03).
Susanna C. Larsson, MSc., and colleagues reported in the Dec. 12 issue of Archives of Internal Medicine.
Women who consumed two cups or more per day lowered their risk for ovarian cancer by 46%, with each additional cup of tea lowering the risk by another 18% (multivariate hazard ratio, 0.82; 95% confidence interval, 0.68-0.99).
Tea's compounds have been extensively studied as chemopreventive agents, the investigators wrote, yet tea's potential against ovarian cancer specifically had yet to be established.
These antioxidant polyphenols, which include catechins, theaflavins, thearubigins, and flavonols, "are abundantly present in both green and black teas and have been shown to inhibit carcinogenesis," Larsson and colleagues wrote.
However, the study also found the women who drank tea also tended to be in better health.
The investigators looked at 61,057 women ages 40 to 76 who filled out a 67-item diet questionnaire between 1987 and 1990. The women were tracked for a mean of 15.1 years through December 2004. At baseline, 68% of the cohort reported drinking tea at least once per month. Most of the women reported drinking black tea with the mean amount consumed being 0.8 cups per day.
Over the study period, 301 women developed invasive epithelial ovarian cancer. The study found even enjoying a spot of tea occasionally offered some benefit.
Compared with women who rarely or never drank tea, those who drank less than one cup daily but more than none reduced their risk (multivariate hazard ratio 0.82; 95% CI 0.62-1.08). Those who drank a full cup per day saw a greater decreased risk (multivariate HR 0.76; 95% CI 0.56-1.04). And women who consumed two or more cups of day had a significantly reduced risk of ovarian cancer (multivariate hazard ratio 0.54, 95% CI0.31-0.91; P value for trend, .03).
These results remained unchanged after factoring in each participant's age of menarche, age of first child birth, age of menopause, hormone use, and family history of breast cancer, the researchers said.
Coffee-drinking appeared to have no effect on ovarian cancer risk in this cohort, the investigators said. The observed association "does not depend on lower coffee consumption among women with high tea consumption," they wrote.
The authors acknowledged there were residual confounding factors. The women who were regular tea drinkers were also those who ate more fruits and vegetables, were slimmer, and generally more health conscious.
"Nevertheless," Dr. Larsson and her team concluded, "the dose-response relationship for tea consumption with ovarian cancer risk makes chance less likely."
More study is needed, they said, but their findings add to the growing body of evidence that supports the cancer-protective potential of tea.
Primary source: Archives of Internal Medicine
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
December 12, 2005
Also covered by: ABC News, Forbes, LA Times
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