Posted on February 6th, 2009 by
Fruits and Vegetables
Researchers affiliated with the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial recently conducted a study to evaluate the relationship between fruit and vegetable intake and the risk of prostate cancer.The study included 1,388 men with prostate cancer and 29,361 men who were enrolled in the screening group of patients in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Individuals completed a 137-item food questionnaire at the beginning of the study.
The researchers concluded: “High intake of cruciferous vegetables, including broccoli and cauliflower, may be associated with reduced risk of aggressive prostate cancer”— however, such a diet did not reduce the overall risk of developing prostate cancer.
Some studies have suggested that lycopene, a carotenoid found in tomatoes and other red fruits, or foods containing lycopene may reduce the risk of certain types of cancer, particularly prostate cancer. Other studies, however, have failed to find this link.
In response to claims about the cancer benefits of lycopene or tomatoes, the FDA conducted a review of the available scientific evidence. The main conclusions of the review were the following:
Noting that lycopene or tomatoes may reduce the risk of cancer progression (rather than cancer initiation), an accompanying editorial explains that studies conducted recently—after the widespread adoption of prostate specific antigen (PSA) testing—may not be able to detect the effect of lycopene. This is because prostate cancers detected by PSA testing tend to be very early-stage, and some of the cancers detected by PSA testing are likely to be indolent, slow-growing cancers; so if lycopene acts later in the process of prostate cancer development, when a cancer is progressing to a more aggressive or advanced stage, a study that includes mainly PSA-detected cancers may fail to detect this effect. This theory remains unconfirmed, however.
Multivitamins and Supplements
Additional results from recent studies have found that the use of multivitamins or supplements with micronutrients does not appear to reduce the risk of developing cancer or affect the prognosis of patients diagnosed with cancer. Several studies are underway to further test a potential association between multivitamin use and cancer. Recently, results from a clinical study indicated that men who used multivitamins more than seven times per week were almost twice as likely as nonusers to develop fatal prostate cancer.
To assess the relationship between multivitamin use and risk of prostate cancer, researchers evaluated information from the National Institutes of Health (NIH)-AARP Diet and Health Study. The study enrolled 295,344 men who were free of cancer at the start of the study.
During five years of follow-up, prostate cancer was diagnosed in 10,241 of the study participants. The prostate cancer was localized in 8,765 cases and advanced in 1,476. There were 179 prostate cancer deaths.
The researchers conclude: “The possibility that men taking high levels of multivitamins along with other supplements have increased risk of advanced and fatal prostate cancers is of concern and merits further evaluation.”
An accompanying editorial notes that these results “add to the growing evidence that questions the beneficial value of antioxidant vitamin pills in generally well-nourished populations and underscore the possibility that antioxidant supplements could have unintended consequences for our health.”
Taken together, results from these studies underscore the confusion surrounding diet and nutrient supplementation and the risk or outcomes of cancer. In general, it appears that fruits and vegetables have a protective effect against the development or aggressiveness of some cancers. Conversely, multivitamin use has not demonstrated a benefit in regards to cancer prevention or survival. It is important for patients to discuss their use of vitamins or other dietary supplements with their physician.
 Kirsh V, Peters U, Mayne S, et al. Prospective study of fruit and vegetable intake and risk of prostate cancer. Journal of the National Cancer Institute. 2007;99:1200-1209.
 Kavanaugh CJ, Trumbo PR, Ellwood KC. The U.S. Food and Drug Administration’s evidence-based review for qualified health claims: tomatoes, lycopene, and cancer. Journal of the National Cancer Institute. 2007;99:1074-85.
 Giovannucci E. Does prostate-specific antigen screening influence the results of studies of tomatoes, lycopene, and prostate cancer risk? Journal of the National Cancer Institute. 2007.99:1060-1062.
 Lawson KA, Wright ME, Subar A et al. Multivitamin use and risk of prostate cancer in the National Institutes of Health-AARP Diet and Health Study. Journal of the National Cancer Institute. 2007;99:754-64
 Bjelakovic G, Gluud C. Surviving antioxidant supplements. Journal of the National Cancer Institute. 2007;99:742-43.
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