Despite the importance of prostate cancer, its causes remain unknown. Scientists do know that genetics plays a strong role, and they have sound evidence that diet and other lifestyle factors are also important.

Since the prostate is a reproductive organ that produces fluid for the ejaculate, researchers have long wondered if sexual factors influence a man’s risk of prostate cancer, but a Harvard study provides good news for sexually active men.

The Harvard ejaculation study

The Health Professionals Follow-Up Study has been collecting information about a large group of volunteers since 1986. All the men are health care providers, including dentists, pharmacists, veterinarians, optometrists, ophthalmologists, and podiatrists. Most are white. In 1992, 29,342 men between the ages of 46 and 81 provided information about their average number of ejaculations per month in young adulthood (age 20–29), middle age (40–49), and in the most recent year. Ejaculations included sexual intercourse, nocturnal emissions, and masturbation. The volunteers provided comprehensive health and lifestyle data every two years until the study concluded in 2000.

The scientists found no evidence that frequen