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LYCOPENE/TOMATO-BASED
FOODS (March 2006)
The article, “Role of Diet in Prostate Cancer
Development and Progression” (JCO, Nov 2005), reported that in four
studies tomato sauce reduced the incidence of prostate cancer by 25% to
80% and that in a meta-analysis of 11 case control and 10 cohort studies a
high intake of tomatoes versus low was associated with an approximately
10% - 20% statistically significant reduction in prostate cancer risk. A
stronger effect was seen for cooked versus raw tomatoes. In another study
“tomato sauce was associated with a 35% decrease in advanced
prostate cancer”. The venerable Health Professionals Follow-Up Study (HPFS)
of 51,529 men compared a high intake of lycopene (from all sources)
versus low, i.e., 2+ servings/week v. < 1 serving /month, and found a 16%
reduction in the risk of prostate cancer. As in other studies, a stronger
risk reduction, e.g. 33%, was found for high versus low intake of
tomato sauce”, the food source with the best lycopene
bioavailability.
A slowing in the progression of
diagnosed prostate cancer has been recently reported from
the HPFS. Men with localized and regionally advanced prostate cancer with
the highest intake of lycopene (top quartile versus lowest) experienced a
44% reduction in time to PSA progression (“Diet after diagnosis and risk
of prostate cancer progression, recurrence, and death (United States), by
Chan JM in Cancer Causes and Control, Jan 2006)”. The analysis was based
on follow-up of 1202 men, appropriately stratified into clinical
prognostic groups, who were diagnosed with prostate cancer during the 10
year study, 392 of whom had principally PSA reoccurrences.
There is no standardized “dose” of lycopene,
but 30 mg/day is frequently recommended, and markedly elevates the plasma
level. Good sources: one half cup of tomato paste, 40 mg, 8 oz canned
tomato juice, 25 mg; tomato soup, 8-11 mg; and a 3” tomato, 1-4 mg.
Not surprisingly, considering the
complexities of studies of this sort, not all studies support a benefit
for lycopene/tomato-based foods. A January 2006 analysis of the NCI
“Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial” found no
evidence that lycopene intake reduced the risk of prostate cancer in the
1338 men who developed the disease, although a subset of men with a
positive family history experienced a decrease in incidence (P=.04).
It
would seem, however that the preponderance of available evidence currently
supports the likelihood that a high consumption of tomato products -
especially when cooked and processed - may reduce the incidence and slow
the clinical progression of prostate cancer.
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