Prostate Cancer and Selenium: Can Selenium Prevent Cancer of the Prostate?

No man wants to hear the news that he has prostate cancer - but many will. Prostate cancer is the most common cancer diagnosed in men over the age of 50. Some men are genetically predisposed to cancer of the prostate, but environmental factors play an important role too - particularly diet. Recently, a new study looked at the trace mineral selenium and prostate cancer - and the role it plays in prevention. Is there a link between cancer of the prostate and low selenium levels?

Health Benefits of Selenium: Does It Reduce the Risk of Prostate Cancer?

Selenium is a trace mineral - one that the body needs in very small quantities, although exactly how the body uses it isn't completely understood. One of the proposed health benefits of selenium is its ability to act as an antioxidant. At low levels, selenium does have antioxidant activity, which helps it protect cells from oxidative damage. But there's evidence it may actually increase oxidative damage at higher doses. More isn't necessarily better when it comes to vitamins and minerals. Selenium is an example of that.

Selenium and Prostate Cancer

When researchers at Ohio State University gave 30 healthy, middle-aged men selenium supplements (200 micrograms of selenium glycinate) for six weeks, it lowered levels of serum PSA, a marker for prostate cancer risk. This is encouraging news, but as the researchers pointed out, reducing PSA doesn't necessarily lower the risk of prostate cancer.

What is PSA?

PSA is a glycoprotein produced by the prostate gland. PSA levels go up in the bloodstream not only with prostate cancer but with benign enlargement of the prostate and prostatitis. Doctors use PSA blood tests along with the digital rectal exam to screen for prostate cancer although an abnormal PSA level is not specific for the disease. But in some cases, using PSA to screen for prostate cancer allows the disease to be detected years before symptoms appear.

Health Benefits of Selenium and Prostate Cancer: Why You Should Interpret These Results with Caution

It might be tempting to get a bottle of selenium and take it in hopes of preventing prostate cancer. Not so fast. This is a small study, and other studies have failed to show that selenium supplements protect against prostate cancer. You can't necessarily assume because selenium supplements lower PSA levels that the risk of prostate cancer goes down too.

Most men get sufficient amounts of selenium in their diet already - more than the recommended daily allowance. Selenium can be toxic at relatively low doses - and one study showed that people who got higher levels of selenium in their diet were at greater risk for type 2 diabetes. Even more concerning is a study showing that some men already diagnosed with prostate cancer had a worse prognosis when they take selenium supplements.

Selenium and Prostate Cancer: The Bottom Line?

Don't use selenium supplements to reduce the risk of prostate cancer. The health benefits of selenium are not well understood, and it can be toxic even in low doses. Wait until more research clearly establishes the health benefits of selenium - and what a safe dose is.

References:

BMC Public Health . 2010;10(564).

Eurekalert.org. " Selenium intake may worsen prostate cancer in some, study reports"