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.[1]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.

• Overall, vegetable and fruit consumption did not affect the risk of developing prostate cancer.
• High vegetable intake significantly decreased the risk of developing prostate cancer that had spread outside of the prostate (advanced prostate cancer).
• Higher intake of broccoli and cauliflower in particular provided significant protection against advanced prostate cancer.

The researchers concluded: 鈥淗igh intake of cruciferous vegetables, including broccoli and cauliflower, may be associated with reduced risk of aggressive prostate cancer鈥濃?however, such a diet did not reduce the overall risk of developing prostate cancer.

Lycopene

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.[2] The main conclusions of the review were the following:

• There is no credible evidence that lycopene reduces the risk of prostate, lung, colorectal, gastric, breast, ovarian, endometrial, or pancreatic cancer.
• There is no credible evidence that tomato consumption reduces the risk of lung, colorectal, breast, cervical, or endometrial cancer.
• There is very limited evidence that tomato consumption reduces the risk of prostate, ovarian, gastric, and pancreatic cancer.

Noting that lycopene or tomatoes may reduce the risk of cancer progression (rather than cancer initiation), an accompanying editorial explains that studies conducted recently鈥攁fter the widespread adoption of prostate specific antigen (PSA) testing鈥攎ay not be able to detect the effect of lycopene.[3] 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.[4] 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.

• There was no link between multivitamin use and risk of localized prostate cancer.
• High levels of multivitamin use were linked with an increased risk of advanced or fatal prostate cancer. Compared with nonusers of multivitamins, men who used multivitamins more than seven times per week had a 32% increased risk of advanced prostate cancer and an almost twofold increased risk of fatal prostate cancer.
• The links between high levels of multivitamin use and advanced or fatal prostate cancer were strongest among men with a family history of prostate cancer, and also among men who took individual micronutrient supplements (such as selenium, beta-carotene, or zinc) in addition to multivitamins.

The researchers conclude: 鈥淭he 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.鈥?/p>

An accompanying editorial notes that these results 鈥渁dd 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.鈥?a id="_ednref5" class="bookmark" title="_ednref5" name="_ednref5" href="http://cancerconsultants.tv/wp-admin/#_edn5">[5]

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.

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