One well designed study found that men who drank four or more glasses of red wine per week saw a reduction in their prostate cancer risk by 50 percent. The same study saw a 60 percent lower incidence of higher stage prostate cancers in these men.
No similar effects could be found with other forms of alcohol including beer and hard liquor.
Other research has studied the effects of resveratrol (the "active" ingredient in red wine) on several pathways of prostate cancer development. Most interesting was the change in the expression of a number of important genes in the PSA and AR (androgen) pathways. Resveratrol slowed down the proliferation and cell cycle speeds causing the cancer cells to take longer before they reproduce.
Studies on resveratrol have also demonstrated that it stimulated cell apoptosis in the prostate cancer cells, causing them to die.
Recommendations:
It appears that red wine could be good for the prostate as well as the heart, but moderation is the key. Four to eight glasses of red wine per week (spread out over several sessions) would implement the recommendations of the study.
Be sure that it is red wine you drink, as whites, blushes and other forms of alcohol did not demonstrate the same prostate protective effect.
