Pomegranates Prevent Growth of
Hormone-Dependent Breast Cancer
Eating fruit, such as pomegranates, that contain anti-aromatase
phytochemicals reduces the incidence of hormone-dependent breast
cancer, according to results of a study published in the January
issue of Cancer Prevention Research, a journal of the American
Association for Cancer Research.
Pomegranate is enriched in a series of compounds known as ellagitannins
that, as shown in this study, appear to be responsible for the
anti-proliferative effect of the pomegranate.
"Phytochemicals suppress estrogen production that prevents
the proliferation of breast cancer cells and the growth of estrogen-responsive
tumors," said principal investigator Shiuan Chen, Ph.D.,
director of the Division of Tumor Cell Biology and co-leader of
the Breast Cancer Research Program at City of Hope in Duarte,
Previous research has shown that pomegranate juice -- punica
granatum L -- is high in antioxidant activity, which is generally
attributed to the fruit's high polyphenol content. Ellagic acid
found in pomegranates inhibits aromatase, an enzyme that converts
androgen to estrogen. Aromatase plays a key role in breast carcinogenesis;
therefore, the growth of breast cancer is inhibited.
Chen, along with Lynn Adams, Ph.D., a research fellow at Beckman
Research Institute of City of Hope, and colleagues, evaluated
whether phytochemicals in pomegranates can suppress aromatase
and ultimately inhibit cancer growth.
After screening and examining a panel of 10 ellagitannin-derived
compounds in pomegranates, the investigators found that those
compounds have the potential to prevent estrogen-responsive breast
cancers. Urolithin B, which is a metabolite produced from ellagic
acid and related compounds, significantly inhibited cell growth.
"We were surprised by our findings," said Chen. "We
previously found other fruits, such as grapes, to be capable of
the inhibition of aromatase. But, phytochemicals in pomegranates
and in grapes are different."
According to Gary Stoner, Ph.D., professor in the Department
of Internal Medicine at Ohio State University, additional studies
will be needed to confirm the chemopreventive action of Urolithin
B against hormone-dependent breast cancer.
"This is an in vitro study in which relatively high levels
of ellagitannin compounds were required to demonstrate an anti-proliferative
effect on cultured breast cancer cells," said Stoner, who
is not associated with this study. "It's not clear that these
levels could be achieved in animals or in humans because the ellagitannins
are not well absorbed into blood when provided in the diet."
Stoner believes these results are promising enough to suggest
that more experiments with pomegranate in animals and humans are
Powel Brown, M.D., Ph.D., medical oncologist and chairman of
the Clinical Cancer Prevention Department at the University of
Texas M. D. Anderson Cancer Center, agreed with Stoner's sentiments
and said these results are intriguing. He recommended that future
studies focus on testing pomegranate juice for its effect on estrogen
levels, menopausal symptoms, breast density or even as a cancer
"More research on the individual components and the combination
of chemicals is needed to understand the potential risks and benefits
of using pomegranate juice or isolated compounds for a health
benefit or for cancer prevention," Brown said. "This
study does suggest that studies of the ellagitannins from pomegranates
should be continued."
Until then, Stoner said people "might consider consuming
more pomegranates to protect against cancer development in the
breast and perhaps in other tissues and organs.
January 5, 2010