SCIENTIFIC INVESTIGATION OF
LYCOPENE
Research on the subject of lycopene and its role in the prevention of
prostate cancer has been ongoing for some time. Many of these
clinical studies have been prospective and/or include data supporting the
value of lycopene. Such data is not definitive, but rather reveals
associations such as higher lycopene blood levels in men without prostate
cancer than those participants with prostate cancer. Another
association reported is a lower rate of prostate cancer in men who
maintain a diet high in lycopene rich foods such as tomatoes. So
far, the ideal double blind placebo controlled study with supplemental
lycopene has not been completed. As a result, lycopene's role in
prostate cancer prevention is indeed promising, but as of yet it has not
been definitively proven. The Physician's Health Study is currently
studying the several substances for the prevention of prostate
cancer. Further NCI is currently funding a phase 1 trial of lycopene
supplements. All studies examined have called for
ongoing study.
SOME PUBLISHED REPORTS:
- Gann et al. 1999 - Cancer Research
A prospective study examining initial plasma caroteniods (including
lycopene) of 1872 men in 1982, then following them for 13 years.
These men were randomly assigned to a placebo group or a group to receive
beta carotene and aspirin supplementation. Of the men studied, 578
developed prostate cancer versus 1294 control subjects. Lycopene was
the only antioxidant with a significantly lower average blood level in
those men with cancer as compared to those without cancer. In those
men not recieving the aspirin and beta carotene, plasma lycopene levels
were very strongly related to a lower risk of developing prostate
cancer. This study concluded that increased consumption of tomato
products and other lycopene-containing foods may reduce occurance of
prostate cancer.
- Giovannucci 1999 - Journal of the National Cancer Institute
This publication is a review of the epidemiologic literature available
regarding cancer risk (not just prostate cancer) and intake of tomato
based foods as well as blood lycopene levels. After identifying 72
studies that fit these criteria, it was found that an inverse relationship
between tomato intake or blood lycopene levels and cancer risk was
reported in 57 of them. Of these 57, it was found that 35 of these
inverse relationships were statistically significant. Further, it
was found that cancer protection from lycopene was strongest for prostate,
colon and stomach cancers, but also appeared to have some benefit in
regard to pancreatic, esophageal, breast, cervical and oral cavity
cancers.
- Pastori et al. 1998 - Biochemical and Biophysical Research
Communications
This publication summarized research with prostate cancer cell lines
and antioxidants including lycopene. It was found that lycopene
alone did not inhibit cell growth, but lycopene in addition to alpha-tocopherol
had a strong inhibitory effect on cell proliferation. This effect
was reported to be synergistic.
- Rao et al. 1999 - Nutrition and Cancer
This study examined plasma and prostate lycopene levels in cancer
patients and controls not afflicted. Though only 12 patients were in
each group, significantly lower serum and prostate lycopene levels
were found in those with cancer. Interestingly, levels of other
carotenoid substances did not vary between the groups. This study
concluded in calling for more research to investigate the role of lycopene
in preventing oxidative damage.
- Norrish et al. 2000 - American Journal of
Epidemiology
This study was done in New Zealand and was a case control study
evaluating prostate cancer risk and intake of lycopene, beta-carotene and
the major food sources of these two carotenoids. They examined 317
prostate cancer patients and 480 controls and determined that there was no
associated decreased risk of prostate cancer based on beta-carotene
intake, but there was a slight protective risk due to lycopene and tomato
based foods.
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