[Editor’s Note: There was a time when only negative news about cannabis could be published. One ‘study’ purported that male sperm counts were reduced by cannabis use. Turns out it might not have been true at all.]
There is a long-held and widespread belief that cannabis lowers a man’s sperm count; a quick Google search will reveal studies claiming a correlation between THC and reduced sperm numbers, or between consuming cannabis and lower sperm concentrations. Yet a recent study from Harvard’s research team reveals substantial and compelling evidence that points to a contrary conclusion.
If you’re a bit surprised to hear that consuming pot may actually raise a man’s sperm count, you aren’t alone. In fact, even the research team from Harvard that released a study earlier this month — in the medical journal Human Reproduction— were a bit incredulous of their discovery.
“We spent a good two months redoing everything, making sure that there wasn’t any error in the data,” co-author Dr. Jorge Chavarro, an associate professor of nutrition and epidemiology at Harvard, said in a press release. “We were very, very surprised about this.”
An Elevated Data Set
To gather their data, the team at Harvard tested 662 men between 2000 and 2017 who were already enrolled at the Massachusetts General Hospital Fertility Center. They collected a total of 1,143 semen samples from this group. In total, 365 of the participants reported having ever smoked pot, and those men provided the researchers with samples containing “significantly higher sperm concentration” than their abstaining peers.
The difference was significant. Researchers found an average of 63 million sperm per milliliter of semen for cannabis smokers, compared to the participants who had never taken a hit, whose sperm count averaged 45 million sperm per milliliter of semen.
The Harvard team was unable to provide much of an explanation for their data, but they did suggest a correlation between smoking cannabis and higher testosterone levels (shh, no one tell Dan Bilzerian).
Dr. Feiby Nassan, one of the authors of the study, pointed out that men with higher testosterone levels are more likely to engage in risky behavior — like, say, consuming an illegal substance — which could help explain the team’s findings. In the same press release, she postulated that “the relations we see between cannabis smoking, sperm counts and testosterone levels are because men with higher testosterone, within normal levels, have higher sperm counts and are more likely to smoke cannabis.”
A Scientific No Man’s Land
The number of participants who admitted to having smoked may, however, have been skewed by the fact that cannabis consumption was still illegal in Massachusetts at the time the study was conducted, and further complicated by the fact that only one in five participants who said they have consumed pot admitted to still doing so. Even though the Harvard study provided some substantial evidence in support of a connection between cannabis consumption and higher sperm counts, it also highlights the lack of research being conducted on cannabis, and the necessity of investing more resources into scientific research to ensure definitive data and more concrete explanations.
After all, the scientists claiming that cannabis reduced a man’s sperm count used, seemingly, equally sound data.
“These unexpected findings from our study highlight that we know too little about the reproductive health effects of cannabis and, in fact, of the health effects in general, to make strong statements about the impact of cannabis on health, with the possible exception of mental health,” lead researcher Chavarro said in the release. “We know a lot less than we think we know.”