I wish I had ejaculated more!

More frequent ejaculation is associated with lower incidence of prostate cancer, according to an update of the Health Professionals Follow-Up Study.

This isn't news. In 2004, they reported the incidence of prostate cancer among men who ejaculated 21+ times per month compared to those who ejaculated 4-7 times per month. They corrected for known risk factors like family history of prostate cancer, BMI, height, smoking, use of Vitamin E, diabetes, and other diet and lifestyle risks. From 1992-2000, they were asked to remember their ejaculation frequency when they were 20-29 years of age, when they were 40-49 years of age, and in the past year. (All the men in the study were at least 40 years of age.)

• Those who ejaculated most frequently in their 20s were 11% less likely to be diagnosed with prostate cancer later.
• Those who ejaculated most frequently in their 40s were 32% less likely to be diagnosed with prostate cancer later.
• Those who ejaculated most frequently in the last year were 51% less likely to be diagnosed with prostate cancer later.
• Over their lifetime so far, those who ejaculated most frequently in the last year were 33% less likely to be diagnosed with prostate cancer later.

The full text of the earlier study is available at this link.

The update adds 10 more years of follow-up to their earlier report. The update included:

• 31,925 men vs. 29,342 in the early report
• 480,831 man-years of data  vs. 222,426 in the early report
• 3,839 cases of prostate cancer vs. 1,449 cases in the early report

The update reports:

• Those who ejaculated most frequently in their 20s were 19% less likely to be diagnosed with prostate cancer later.
• Those who ejaculated most frequently in their 40s were 22% less likely to be diagnosed with prostate cancer later.
• The abstract doesn't report the hazard ratios for ejaculation frequency in the last year or during their lifetime-to-date.
• All of the associations are statistically significant and clinically meaningful.

This is based on recollections of their ejaculatory frequency in their 20s and 40s, and may represent a romantic view of their younger days. But the pattern holds for ejaculations in the last year too, at least in the earlier report. Ejaculatory frequencies are correlated by age: those who ejaculated most frequently in their 20s, also ejaculated most frequently in their 40s and in the past year.

It may well be true that there is a causal connection. It is possible that the prostate tissue increases in tone, just as muscle tissue does, and degenerative changes may be caused by disuse.

It may also be true that men who have higher testosterone levels ejaculate more frequently and have lower incidence of prostate cancer. We know that the converse is true - men with historically lower natural levels of testosterone (called hypogonadal) have higher incidence of prostate cancer.

Whatever the explanation, increasing one's ejaculatory frequency seems to be a prudent measure worth taking. It carries no risk, and has obvious benefits.