There are many unsubstantiated myths about the effects of masturbation but, according to a team of Australian researchers, there is some encouraging news for men — frequent ejaculation can help protect against prostate cancer.

Graham Giles and colleagues from The Cancer Council Victoria surveyed 1,079 patients with prostate cancer and 1,259 healthy men, asking them about their sexual habits. When they compared the data from each group, they found that the more men ejaculated between the ages of 20 to 50, the less likely they were to develop prostate cancer. The results were most significant for men in their twenties, as ejaculation more than five times a week by men in this age group reduced their risk of prostate cancer by one-third.

According to Giles, “It's a prostatic stagnation hypothesis”. Frequent ejaculation prevents the build up of harmful carcinogens in the testes and “The more you flush the ducts out, the less [carcinogen] there is to hang around and damage the cells that line them” (CNN, 17 July 2003).

Previous studies have indicated that multiple partners or a high frequency of sexual activity actually increases the risk of prostate cancer. However, Giles suggests these results most likely reflect study design, which defined sexual activity as sexual intercourse, rather than number of ejaculations. “Had we been able to remove ejaculations associated with sexual intercourse, there should have been an even stronger protective effect of other ejaculations.” claims Giles (NewScientist, 16 July 2003). So, it looks like men might have a way to beat prostate cancer.