Reducing the risk of prostate diseases can be difficult, as the exact causal mechanisms are not completely known. However, there is a little bit of evidence that to maintain prostate health, supplements like saw palmetto, beta sitosterol, and selenium may help. Evidence is not conclusive, and some studies conflict with others, but many of these supplements are probably safe to take and may be worth trying for those with prostate problems.

Saw palmetto extract is probably the best known prostate supplement, and is primarily used to treat benign prostatic hyperplasia (BPH), or enlarged prostate syndrome, which generally causes frequent night urination. Some research has found that it can be as effective as many of the typical drugs given for BPH (such as Flomax), but other research has not been able to find a difference compared to the placebo used in the study. Since it is probably relatively safe to take, it might be worth a shot if you are suffering from an enlarged prostate, although keep in mind it can take several months to begin working.

Another plant extract called beta-sitosterol (found in many different plants) is popular in Europe, also primarily for treatment of BPH. Preliminary research has found that it can help even out urinary problems, similar to the effectiveness of saw palmetto.

In addition beta-sitosterol may even help with prostate cancer. In a 2001 study published in the European Journal of Cancer Prevention, beta-sitosterol inhibited cancer growth and metastasis, although more research is needed in this area.

Vitamin D is another recently popular anti-cancer supplement, although research is still very preliminary, with at least some studies that conflict. Some of these have looked at sunlight levels (the natural way to acquire vitamin D), finding higher cancer rates in countries with less sunlight. Others have not been able to find a connection. Since many people are usually deficient in vitamin D, and the supplement is relatively safe to take in moderate doses, it may make a fine addition to the diet.

However, a related supplement may actually increase cancer. Researchers in 2008 discovered that men with higher than normal blood calcium levels actually have up to three times the risk of developing fatal prostate cancer later in life. Again, this research is still in the early stages, and the precise mechanism is still unknown.

Finally, there was some thin evidence that selenium may reduce the risk of prostate cancer. A 1996 study that set out to find a correlation between selenium and skin cancer instead found a reduced risk of prostate cancer in men. However, a 2009 study on 35,000 men did not find a correlation between selenium and prostate cancer, so its effectiveness in this respect is still an unknown.