New research from the Channing Laboratory at Brigham
and Women’s Hospital (BWH) reports that frequent consumption of foods
containing the flavonoid kaempferol, including non-herbal tea and
broccoli, was associated with a reduced risk of ovarian cancer. The
researchers also found a decreased risk in women who consumed large
amounts of the flavonoid luteolin, which is found in foods such as
carrots, peppers and cabbage. These findings appear in the November 15,
2007 issue of the International Journal of Cancer.
“This is good news because there are few lifestyle factors known to
reduce a woman’s risk of ovarian cancer,” said first author Margaret
Gates, ScD, who is a research fellow at BWH. “Although additional
research is needed, these findings suggest that consuming a diet rich
in flavonoids may be protective.”
The causes of ovarian cancer are not well understood. What is known
is the earlier the disease is found and treated, the better the chance
for recovery; however, the majority of cases are diagnosed at an
advanced (metastasized) stage after the cancer has spread beyond the
ovaries. According to the National Cancer Institute, the 5-year
relative survival rate for women diagnosed with localized ovarian
cancer is 92.4 percent. Unfortunately, this number drops to 29.8
percent if the cancer has already metastasized.
In this first prospective study to look at the association between
these flavonoids and ovarian cancer risk, Gates and colleagues
calculated intake of the flavonoids myricetin, kaempferol, quercetin,
luteolin and apigenin among 66,940 women enrolled in the Nurses’ Health
Study. In this population, 347 cases of epithelial ovarian cancer were
diagnosed between 1984 and 2002.
Although total intake of these five common dietary flavonoids was
not clearly beneficial, the researchers found a 40 percent reduction in
ovarian cancer risk among the women with the highest kaempferol intake,
compared to women with the lowest intake. They also found a 34 percent
reduction in the risk of ovarian cancer among women with the highest
intake of luteolin, compared to women with the lowest intake.
“In this population of women, consumption of non-herbal tea and
broccoli provided the best defense against ovarian cancer,” concluded
Gates, who is also a research fellow at the Harvard School of Public
Health. “Other flavonoid-rich foods, such as onions, beans and kale,
may also decrease ovarian cancer risk, but the number of women who
frequently consumed these foods was not large enough to clearly
evaluate these associations. More research is needed.”
The research was funded by the National Cancer Institute.