If you're a man worried about developing prostate cancer, there appears to be at least one preventative step you can take to lower your risk from the comfort of your own bedroom.
Several studies have linked frequent ejaculation — during sex, masturbation, or while you're sleeping — to reduced risk of prostate cancer.
How much of a difference can ejaculating really make?
According to a 2016 study published in the journal European Urology, quite a bit.
Researchers surveyed 32,000 men from 1992 to 2010 and found that participants who reported ejaculating at least 21 times per month during their 20s were 19 percent less likely to develop prostate cancer than those who ejaculated seven times per month or less.
Frequent ejaculation during your 40s also appears to reduce your prostate cancer risk by 22 percent, the study found.
"While our findings should be confirmed in studies that evaluate the potential biological mechanisms underlying the observed associations, the results of our study suggest that ejaculation and safe sexual activity throughout adulthood could be a beneficial strategy for reducing the risk of prostate cancer," Jennifer Rider, lead author of the study, said in a press release.
There's no magic number of times a person should ejaculate to reduce their risk. What the study findings suggest is a dose-dependent relationship, where the risk becomes lower the more frequently a person ejaculates.
This isn't the first time that researchers have studied how ejaculation affects cancer risk. In 2003, a team of Australian researchers compared ejaculation frequency among about 2,300 men — half of whom had been diagnosed with prostate cancer. The results showed that ejaculating five to seven times per week were 36 percent less likely to develop prostate cancer compared to those who ejaculated less than two times per week.
While the results have been consistent, researchers aren't certain about why ejaculating seems to reduce the risk of prostate cancer.
Riders told Reuters that her team had one theory about the connection: "Ejaculation frequency is, to some extent, a measure of overall health status in that men at the very low end of ejaculation — zero to three times per month — were more likely to have other [medical problems] and die prematurely from causes other than prostate cancer."
Still, further research is needed to identify the biological mechanism responsible for reducing the risk.