Vitamins and medication
Evidence from epidemiological studies supports a possible protective role in reducing prostate cancer for dietary selenium, vitamin E,lycopene, and soy foods. High plasma levels of Vitamin D may also have a protective effect. Estrogens from fermented soybeans and other plant sources (called phytoestrogens) may also help prevent prostate cancer.The selective estrogen receptor modulator drugtoremifene has shown promise in early trials. Two medications which block the conversion of testosterone to dihydrotestosterone,finasteride and dutasteride, have also shown some promise. The use of these medications for primary prevention is still in the testing phase, and they are not widely used for this purpose. The initial problem with these medications is that they may preferentially block the development of lower-grade prostate tumors, leading to a relatively greater chance of higher grade cancers, and negating any overall survival improvement. More recent research found that finasteride did not increase the percentage of higher grade cancers. A 2008 study update found that finasteride reduces the incidence of prostate cancer by 30%. In the original study it turns that that the smaller prostate caused by finasteride means that a doctor is more likely to hit upon cancer nests and more likely to find aggressive-looking cells. Most of the men in the study who had cancer - aggressive or not - chose to be treated and many had their prostates removed. A pathologist then carefully examined every one of those 500 prostates and compared the kinds of cancers found at surgery to those initially diagnosed at biopsy. Finasteride did not increase the risk of High-Grade prostate cancer.
Green tea may be protective (due to its polyphenol content), although the most comprehensive clinical study indicates that it has no protective effect. A 2006 study of green tea derivatives demonstrated promising prostate cancer prevention in patients at high risk for the disease. Recent research published in the Journal of the National Cancer Institute suggests that taking multivitamins more than seven times a week can increase the risks of contracting the disease. This research was unable to highlight the exact vitamins responsible for this increase (almost double), although they suggest that vitamin A, vitamin E and beta-carotene may lie at its heart. It is advised that those taking multivitamins never exceed the stated daily dose on the label. Scientists recommend a healthy, well balanced diet rich in fiber, and to reduce intake of meat. A 2007 study published in the Journal of the National Cancer Institute found that men eatingcauliflower, broccoli, or one of the other cruciferous vegetables, more than once a week were 40% less likely to develop prostate cancer than men who rarely ate those vegetables. The phytochemicals indole-3-carbinol and diindolylmethane, found in cruciferous vegetables, hasantiandrogenic and immune modulating properties.
More frequent ejaculation also may decrease a man's risk of prostate cancer. One study showed that men who ejaculated five times a week in their 20s had a decreased rate of prostate cancer, though other studies have shown no benefit. The results contradict those of previous studies, which have suggested that having had many sexual partners, or a high frequency of sexual activity, increases the risk of prostate cancer by up to 40 percent. The key difference is that these earlier studies defined sexual activity as sexual intercourse, whereas this study focused on the number of ejaculations, whether or not intercourse was involved. Another study completed in 2004 reported that Most categories of ejaculation frequency were unrelated to risk of prostate cancer. However, high ejaculation frequency was related to decreased risk of total prostate cancer. The report abstract concluded, Our results suggest that ejaculation frequency is not related to increased risk of prostate cancer. A 2008 study showed that men who engaged in frequent masturbation, of about two to seven times a week, at the ages of 20s and 30s, had a higher rate of prostate cancer, while men who engaged in frequent masturbation, once a week, at the age of 50s had a lower rate.
Oils and fatty acids
In experimental models using mice have been tested, dietary and serum omega-6 polyunsaturated fatty acids (PUFAs) increased prostate tumor growth,and has sped up histopathological progression, and decreased survival, while the omega-3 fatty acids, in the same situation, had the opposite, beneficial effect.
Men with higher serum levels of the short-chain omega-6 fatty acid linoleic acid have higher rates of prostate cancer. However, men with high serum linoleic acid, but not palmitic, can reduce the risk of prostate cancer by taking tocopherol supplementation
Men with elevated levels of long-chain omega-3 fatty acids (EPA and DHA) had lowered incidence.
A long-term study reports that blood levels of trans fatty acids, in particular trans fats resulting from the hydrogenation of vegetable oils, are associated with an increased prostate cancer risk.
Some researchers have indicated that serum myristic acid and palmitic acid and dietary myristic and palmitic saturated fatty acids and serum palmitic combined with alpha-tocopherol supplementation are associated with increased risk of prostate cancer in a dose-dependent manner. Serum association of these and other saturated fatty acids was also investigated by another study.
The American Dietetic Association and Dieticians of Canada report a decreased incidence of prostate cancer for those following a vegetarian diet.