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, Calif.
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
warranted.
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
preventive agent.
"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."
SOURCE