Orgasms don’t just feel good—they may actually be good for us.

A team of Harvard researchers just published the results of an 18-year longitudinal study finding that men who ejaculate more frequently have a lower risk of developing prostate cancer, the most common form of cancer among men in the US.

They aren’t the first group of scientists to find support for this idea—far from it. In fact, over the past two decades, study after study has yielded similar conclusions.

However, the latest study addressed limitations of previous research by tracking men for a much longer period of time and by trying to rule out alternative explanations.

These researchers analyzed data from 31,925 American men who took part in a health study that began in 1986 and continues to this day. In fact, these dedicated men are still filling out follow-up surveys ever other year!

We’re talking about an impressive dataset, but I should caution that more than 90 percent of the sample is white and all of them had jobs as health professionals when the study began. In short, it’s a cool study, but far from a representative sample.

In the 1992 wave of data collection, these men (who ranged in age from their 40s to their 70s) were asked to estimate the average number of ejaculations they had per month while they were in their 20s, their 40s, and in the past year.

In later surveys, they were asked whether they had been diagnosed with prostate cancer. If so, researchers confirmed this by checking medical records.

What researchers found was that prostate cancer was diagnosed less often among men who reported ejaculating more frequently. This was true regardless of whether they looked at men’s ejaculation frequency in their 20s, 40s, or previous year.

To be clear, this is not to say that frequent ejaculators had no risk of prostate cancer—only that their risk was lower. For example, among men who ejaculated more than 13 times per month during each of the three time periods, their risk of being diagnosed with prostate cancer was 25 to 28 percent lower than men who ejaculated just four to seven times per month.

I should also clarify that the reduced risk among frequent ejaculators was most pronounced for the least aggressive kind of prostate cancer.

But is ejaculation really the key here? Or might the observed difference in prostate cancer risk have more to do with high- and low-frequency ejaculators just having totally different lifestyles? For example, maybe these groups differ in terms of weight, exercise, and/or alcohol consumption.

Importantly, researchers found that even when taking all of these other variables into account, they could not fully explain the link between ejaculation frequency and odds of developing prostate cancer.

In other words, ejaculation had a “robust” association with this cancer.

Although this study builds upon shortcomings of previous research, it’s not free of limitations. Most importantly, it’s an observational study, which doesn’t show cause-and-effect. Although this is the strongest evidence we have to date showing a link between frequent ejaculation and lower prostate cancer risk, we still can’t say anything definitive.

In addition, researchers asked men to estimate how often they ejaculated, and these guys probably weren’t all that accurate in recalling this information, especially when thinking back several decades! The point wasn’t to obtain perfect accuracy, but rather to simply categorize guys into high- and low-frequency groups—something I suspect this measure likely did successfully.

Lastly, researchers didn’t ask these men how they had their orgasms. Did they occur during sex or during masturbation? Would both types of orgasms be related to cancer risk in the same way? We need more research to know.

Caveats aside, the other big question is this: if it really is true that frequent orgasms reduce the odds of developing prostate cancer, how do we explain why?

The most popular idea is the prostate stagnation hypothesis. The prostate produces a big part of the fluid that makes up semen, and the thought is that there may be a danger in letting too much of it accumulate because certain components of that fluid may be carcinogenic.

Put another way, guys who ejaculate early and often may be “flushing the pipes” of potential cancer-causing secretions before they can cause problems.

It might very well be. Again, though, we can’t say for sure that ejaculating more often will necessarily ward off prostate cancer. However, the weight of the evidence suggests that having frequent orgasms is more likely to help rather than hurt your health.

Justin Lehmiller, PhD is a sex educator and researcher at Ball State University and author of the blog Sex and Psychology. Follow him on Twitter @JustinLehmiller.