The following have been proven not to affect the risk of prostate cancer, or their effects on prostate cancer risk are not known:
Selenium and vitamin E
The Selenium and Vitamin E Cancer Prevention Trial (SELECT) studied whether taking vitamin E and selenium (a mineral) will prevent prostate cancer. The selenium and vitamin E were taken separately or together by healthy men 55 years of age and older (50 years of age and older for African-American men). The study showed that taking selenium alone or selenium and vitamin E together did not decrease the risk of prostate cancer.
It is not known if decreasing fat or increasing fruits and vegetables in the diet helps decrease the risk of prostate cancer or death from prostate cancer. In the PCPT trial, certain fatty acids increased the risk of high-grade prostate cancer while others decreased the risk of high-grade prostate cancer.
Regular use of multivitamins has not been proven to increase the risk of early or localized prostate cancer. However, a large study showed an increased risk of advanced prostate cancer among men who took multivitamins more than seven times a week.
Some studies have shown that a diet high in lycopene may be linked to a decreased risk of prostate cancer, but other studies have not. It has not been proven that taking lycopene supplements decreases the risk of prostate cancer.
Cancer prevention clinical trials are used to study ways to prevent cancer.
Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.
The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include eating fruits and vegetables, exercising, quitting smoking, or taking certain medicines, vitamins, minerals, or food supplements.