For ages, the conventional wisdom about marijuana and male reproductive health was that one did not benefit the other. Weed was kryptonite for healthy sperm; don't partake in one if you want the other. Scientific studies backed that up.
But all it takes is one new study to blow up what we thought we knew, and that study was published this month. After analyzing the ejaculate of more than 600 men, researchers from the Harvard T.H. Chan School of Public Health found that men who reported using cannabis had higher sperm counts than men who reported never using cannabis. That's not what we, or the researchers, expected to hear.
For the study, published in the scientific journal Human Reproduction, researchers went straight to the source—a fertility clinic in Massachusetts—to examine the connection between sperm count and cannabis, collecting 1,143 semen samples from 662 male patients. These men also filled out a questionnaire about their marijuana use, past and present, and half the men had blood samples taken to test for reproductive hormone levels. The researchers found that men who reported smoking marijuana had, on average, "significantly higher" sperm concentrations than men who did not smoke: 62.7 million sperm per milliliter of ejaculate in smokers versus 45.4 million sperm per milliliter of ejaculate in non-smokers.
Both of these sperm-per-milliliter-of-ejaculate counts are well within the World Health Organization's defined range for "normal" levels, which bottoms out at 15 million/mL. Interestingly, the researchers found that while only 5 percent of the men who reported smoking marijuana fell short of WHO's low end, 12 percent of the non-smokers missed the mark.
There was no significant difference in sperm count between men who said they used to smoke pot and men who said they're still getting high. Smoking more pot was associated with higher testosterone levels.
"These unexpected findings highlight how little we know about the reproductive health effects of marijuana, and in fact of the health effects of marijuana in general," said study co-author Jorge Chavarro, an associate professor of nutrition and epidemiology at Harvard, said in a press release. "Our results need to be interpreted with caution, and they highlight the need to further study the health effects of marijuana use."
We aren't short on studies examining marijuana and sperm, but we are short on anything conclusive. In 2015, scientists studied a a thousand healthy, young Danish men and found pretty much the exact opposite: Smoking marijuana at least once a week was associated with lower sperm counts in that sample. In December, a different study found that men with high levels of THC in their pee were more likely to have lower sperm counts—but the results came from just 24 men. Previous studies that have found cannabis to be harmful to male reproductive health were conducted among men with histories of drug abuse—or mice.
Men who reported smoking marijuana had, on average, "significantly higher" sperm concentrations than men who did not smoke.
Take it a step past sperm count to the actual conception of babies, and we get a different conclusion. In January, Boston University released findings saying that marijuana use did not alter a couple's likelihood of getting pregnant. But generally speaking, doctors advise men and women to not use marijuana if they are trying to get pregnant or are pregnant, simply because not enough is known about its effects.
Harvard's new research isn't conclusive, either. The men self-reported illegal drug use, which isn't the most trustworthy method, and they were patients seeking fertility treatment, so the results can't be applied to the entire population. And because this is a simple correlation, there might be a different explanation altogether. For example, men with higher testosterone levels are more likely to do "risky" things like smoke weed, and are also more likely to have higher sperm counts. Or, lighter marijuana use might be beneficial because of their effects on the endocannabinoid system, which is linked to fertility, whereas heavy usage is not.
It's difficult to study marijuana when the federal government still classifies it as a highly dangerous, highly illegal substance. But a new bill introduced in the Senate to decriminalize weed—called S. 420, I kid you not—could clear the way for more medical research. And with more research, we'd get a fuller understanding of what cannabis does to men's junk. Until then, it's your sperm. Do what you will to keep it healthy.
From: Esquire US