Tea May Fight Ovarian, Breast Cancers
Broccoli, Kale Also Potent Sources of Cancer-Fighting Flavonoids
April 5, 2006 (Washington) -- Potent chemicals found in tea can help fight
ovarian and breast cancers, new research suggests.
Broccoli and kale are also rich sources of cancer-fighting flavonoids, says
Margaret Gates, a doctoral candidate at the Harvard School of Public Health who
has been studying their link to ovarian cancer. Flavonoids are believed to have
antioxidant and anti-inflammatory activity. Her research suggests that women
who increase their consumption of kaempferol, a type of flavonoid, can lower
their risk of ovarian cancer by nearly 40%.
A second study shows that women who consume a diet rich in other types of
flavonoids - specifically, flavones, flavan-3-ols, and lignans -- can reduce
their chance of developing breast cancer by 26% to 39%.
If you can't keep all those scientific names straight, no worries: It
basically comes down to the same thing, the researchers tell WebMD.
For lowering ovarian cancer risk, "tea in particular may be
important," Gates says.
For breast cancer protection, "tea again is the predominant
contributor," Brian Fink, MPH, a doctoral candidate at the University of
North Carolina at Chapel Hill.
Both new studies were presented at the annual meeting of the American
Association for Cancer Research.
Kaempferol Fights Ovarian Cancer
Gates analyzed data on 66,384 participants of the Nurses' Health Study, none
of whom had ovarian cancer at the start of the study. Every few years,
beginning in 1984, the women filled out detailed questionnaires that asked
about their consumption of more than 120 foods.
Using the data, the researchers calculated each participant's intake of five
different flavonoids -- myricetin, kaempferol, quercetin, luteolin, apigenin --
and of total flavonoids. Between 1984 and 2002, 344 of the women were diagnosed
with ovarian cancer.
Gates says there was no link between total flavonoid consumption and ovarian
cancer. Nor did myricetin, quercetin, luteolin, or apigenin significantly
But the greater the consumption of kaempferol -- which the nurses got mostly
from tea, broccoli, and kale -- the lower their chance of developing ovarian
So just how much kaempferol is enough? Gates says 10 milligrams to 12
milligrams a day, the amount found in four cups of tea or two cups of broccoli
daily, appears to be protective. Both green tea and black tea will do the
trick, she adds.
Gates says she'd like to see further research in this area. "If
confirmed, flavonoid consumption would provide an important target for ovarian
cancer protection," she says.
To look at the flavonoid-breast cancer link, Fink studied data from a large
study of breast cancer rates and risk factors conducted among women living on
Long Island, N.Y., in the mid-1990s. In 1996 and 1997, nearly 3,000
participants were interviewed at home about their lifestyle habits and given
questionnaires that asked what they ate and how much they ate.