Pomegranate Juice & Prostate Cancer
"A critical weekly review of important new research findings for health-conscious readers..."
Last Updated: 10/12/2008
POMEGRANATE
JUICE & PROSTATE CANCER
According
to the American Cancer Society, an estimated 186,000 men will
be diagnosed with prostate cancer in the
Biologically
active compounds in pomegranate juice, known as ellagitannins, are known to have powerful antioxidant
and
anti-inflammatory effects. These powerful dietary
antioxidants are related,
chemically, to the antioxidants also found in green tea, which is
another area
of intense focus in cancer prevention research (please review my
archived
columns for reviews of important and recently published research on the
potential
health effects of green tea).
Previous
research studies, looking at human prostate cancer cells
growing in cell cultures, and implanted in mice as well, have suggested
potential
cancer prevention and cancer treatment roles for pomegranate juice
extracts. In a
recently published
clinical study, pomegranate juice supplements were found to slow down
the
progression of recurrent prostate cancer in patients who had previously
undergone treatment with surgery or radiation therapy.
Moreover, when the serum of these patients
was added to cell cultures containing human prostate cancer cells, the
serum
collected after patients consumed pomegranate juice both slowed down
the growth
of the prostate cancer cells and increased the death rate of these same
cells.
A
new research study, just published in the journal Molecular Cancer Therapeutics by
scientists at UCLA, adds important new information about the possible
role of
pomegranate juice in the prevention and treatment of prostate cancer.
Nuclear
Factor Kappa-B, or NF-κB, consists of a group of proteins
referred to, collectively, as transcription factors.
Transcription factors act by activating
multiple genes in both normal cells and cancer.
Activation of the NF-κB signaling pathway turns on a
variety of genes
that appear to play an important role in the development and
progression of
many cancers, including prostate cancer.
NF-κB has also been implicated in the effects of chronic
inflammation on
the development of several cancers, including prostate cancer. Moreover, activation of
NF-κB also appears to
enable cancer cells to resist the effects of chemotherapy and other
cancer
treatments, and appears to be linked with more aggressive tumor
biology, and a
resulting increase in the risk of cancer recurrence.
While
almost all prostate cancer cells are initially sensitive to
hormonal therapies that block the male sex hormones (androgens),
patients with
advanced prostate cancer who are treated with androgen blocking agents
will
eventually develop prostate cancer cells that are resistant (or
androgen-independent) to such therapies.
When metastatic prostate cancer tumors become
androgen-independent,
these tumors then become unresponsive to most clinical therapies.
In
this study, pomegranate extract was added to androgen-independent human
prostate cancer cells in the laboratory, resulting in an inhibition of
NF-κB
that was proportional to the amount of pomegranate extract that was
added. This
inhibition of the NF-κB pathway, which
was induced by pomegranate extract, also resulted in a decreased rate
of growth
of the androgen-independent prostate cancer cells, as well as an
increased
death rate among these cells.
When
androgen-sensitive human prostate cancer tumors are transplanted
into mice, they gradually become androgen-independent following
castration of
the mice. In this
research study, the
authors also implanted androgen-sensitive human prostate cancer cells
into laboratory
mice. Some mice
were given pomegranate
extract or pomegranate juice, while other mice were not given any
pomegranate
supplements. Subsequently,
as the
transplanted prostate cancer cells began to grow into tumors, all mice
were
then castrated to induce androgen insensitivity in their implanted
tumors. The authors
subsequently found that the mice
that had received pomegranate supplements developed significantly
smaller
tumors when compared to the mice that had not received pomegranate
extract. Moreover,
the development of androgen
insensitive tumors was significantly delayed in the mice that had
received the
pomegranate supplement, suggesting that pomegranate extract may not
only be
able to shrink prostate cancer tumors, but may also be able to maintain
prostate cancer cells in the more favorable androgen-sensitive state. PSA levels in the blood of
the mice that
received the pomegranate extract were also significantly lower than
what was
observed in the control animals that did not receive the extract in
their
diets. All of these
favorable effects
that were observed in the mice that had received pomegranate extract
appeared
to be linked directly to an inhibition of the NF-κB signaling pathway.
The
results of this study are highly intriguing, as they suggest that,
at least in mice, pomegranate extracts may be able to slow prostate
cancer cell
growth, as well as significantly delaying the transition of prostate
tumors
from the more favorable androgen-sensitive state to the
treatment-resistant androgen-insensitive
state. Because
rising levels of NF-κB
activity have previously been linked to the development of prostate
cancer, as
well as to the increased biological aggressiveness of prostate cancer
cells,
the inhibition of NF-κB with pomegranate extracts could conceivably
reduce the
risk of developing prostate cancer and might
also reduce the growth rate and aggressiveness of already established
prostate
cancer. Additionally,
and importantly,
the results of this study suggest that NF-κB, itself, probably plays a
dominant
role in the development of androgen independence in prostate cancer
tumors,
and, therefore, that blocking NF-κB with pomegranate extract may
maintain
metastatic prostate cancer tumors in the more treatable
androgen-sensitive
state.
But,
before you go to your local grocery store and buy all of the
pomegranates that they have in stock, there are a couple of important
caveats that
must be mentioned. First,
as I always
note with laboratory studies that involve cells growing in a Petrie
dish, or
tumor cells implanted into laboratory animals, there is absolutely no
guarantee
that human patients will respond in the same ways as were observed in
the
laboratory. A
second caveat is that the
mice utilized in this research study were fed the daily equivalent of
10 times
as much pomegranate extract and juice as an ordinary human is likely to
take in
a day. Whether or
not smaller and more reasonable
amounts of pomegranate supplementation will produce the same beneficial
effects
(in either mice or humans!) remains to be seen.
Finally,
this study was supported with funding from the dominant producer
of pomegranates and pomegranate juice in the
Although
the results of this study cannot tell us if pomegranate juice
is able to either prevent prostate cancer in humans or decrease its
aggressiveness once it has already developed, there have been very few
reports
of any apparent serious ill affects associated with pomegranate juice
consumption. And
so, for most people, a swig or two of
pomegranate juice a day shouldn’t be a problem.
However, you should still check with your physician before
consuming
significant quantities of pomegranate juice, as there have been some
reports of
adverse reactions involving heart and cholesterol-lowering medications
(pomegranate juice appears to increase the blood levels of certain
medications,
which may lead to significant adverse health reactions).
Disclaimer:
As always, my advice to readers is to seek the advice of your physician
before making any significant changes in
medications, diet, or level of physical activity.
Dr. Wascher is an oncologic surgeon, professor of surgery, a widely published author, and the Director of the Division of Surgical Oncology at Newark Beth Israel Medical Center
http://www.sbhcs.com/hospitals/newark_beth_israel/mservices/oncology/surgical.html
Send your feedback to Dr. Wascher at
rwascher@doctorwascher.net
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Copyright 2008. Robert A. Wascher, MD, FACS. All rights reserved.
Dr. Wascher's Archives:
10-5-2008: Central Obesity & Dementia; Diet, Vitamin D, Calcium, & Colon Cancer
9-28-2008: Publication & Citation Bias in Favor
of Industry-Funded Research?
9-21-2008: Does TylenolŪ (Acetaminophen) Cause Asthma?
9-14-208: Arthroscopic Knee Surgery- No Better than
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8-23-2008: Alcohol Abuse Before & After
Military Deployment; Running & Age; Running & Your
Testicles
3-16-2008: Benefits
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Conversations about Sex; Soy (Genistein) & Prostate Cancer
2-23-2008: Universal
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2-3-2008: Vitamin D
& Cardiovascular Health; Vitamin D & Breast Cancer;
Green Tea & Colorectal Cancer
1-12-2008: Statins,
Diabetes & Stroke and Obesity; GERD & Esophageal Cancer
12-31-2007: Minority Women, Hormone Replacement Therapy
& Breast Cancer; Does Health Insurance Improve Health?