Men who smoke marijuana may have higher sperm cells than those who have never used the drug, find a surprising new study.
The results are "not consistent" with previous research that has suggested that marijuana has a detrimental effect on male testicular function, researchers say.
The study, published in Feb. 6 The issue of the journal Human Reproduction, however, does not mean that men should start smoking pot for their sperm cells.
The results are far from crucial and more research is needed to understand whether smoking marijuana could actually have a positive effect on sperm production at certain levels.
But the study emphasizes how little researchers know about the reproductive health effects of marijuana, studying senior author Dr. Jorge Chavarro, a professor of nutrition and epidemiology at Harvard T.H. Chan Public Health School in Boston, said in a statement. "We know much less than we think we know." [25 Odd Facts About Marijuana]
Marijuana and sperm
Previous studies had suggested that smoking marijuana may reduce a man's sperm, especially among heavy users. For example, researchers from Denmark in 2015 found that men who smoke marijuana more than once a week had sperm that was nearly 30 percent lower than those who did not smoke marijuana, or those who used the drug less often.
However, the effect of more moderate marijuana use on male sperm counts is less clear.
In the new study, researchers analyzed information from 662 men who, together with their partners, were evaluated for infertility from 2000 to 2017 at the Massachusetts General Hospital Fertility Center. The men answered the question of how often they smoke marijuana or used other drugs, and they also gave sperm and blood tests.
All in all, just over half of the men (55 percent) ever reported smoking marijuana during their lifetime, and 11 percent said they were currently smoking marijuana.
The researchers found that men who ever reported having smoked marijuana had an average sperm concentration of 63 million sperm. Milliliter of semen compared to 45 million sperm per milliliter of semen among those who had never used marijuana. The results were held even after the researchers took into account some factors that could have affected the semen concentration, such as age, cigarette smoking and alcohol consumption.
In addition, only 5 percent of marijuana smokers had lower sperm concentrations – that is, less than 15 million sperm per day. Milliliter of semen. Among men who never smoked marijuana, 12 percent had lower sperm concentrations than normal.
Among men who had ever smoked marijuana, those who used it more often had higher testosterone levels than those who used it less often.
Interestingly, every extra year that had elapsed since a man who last used marijuana was bound to a small increase in sperm.
"Our results contradicted what we hypothesized at the start of the study," says lead author Feiby Nassan, a postdoctoral researcher at Harvard T.H. Chan Public Health School said in the statement.
But the study can be interpreted in several ways. It may be that low or moderate levels of marijuana use have a beneficial effect on sperm production, but heavier use reverses this effect. Or it may also be that men with higher testosterone levels are more likely to engage in "risky" behaviors such as. Drug use; and the researchers found the relationship between marijuana and sperm, "because men with higher testosterone within normal levels have higher sperm counts and are more likely to smoke cannabis," says Nassan.
The jury still out
It is known that moderate to heavy use of tobacco or alcohol is bound to lower sperm counts, but if marijuana has the same effect, there is a debate, Dr. Sarah Vij, urologist at the Cleveland Clinic, who was not involved in the study.
Vij said she applauded the authors to look at this issue as it is a subject that requires more research.
But the new study does not provide a decisive answer. "Overall, the jury is still out about how marijuana affects a man's fertility potential," Vij Live Science said.
Vij pointed out that both marijuana users and nonusers in the study had normal sperm cells on average. So the study cannot draw any conclusions as to whether marijuana use is bound to better fertility.
In addition, it takes about three months for men to undergo a full cycle of sperm production to produce mature sperm. That means that the use of marijuana years ago "really should have any influence on everyone [a man’s] current fertility state, "Vij said.
And yet, the study still found that men who said they used marijuana at least a year ago had higher sperm than men who used it more recently. Vij said she wondered if "there is something that goes hand in hand with marijuana use" bound to better sperm production.
The researchers also noted that their study was conducted among men who visited a fertility clinic, and therefore the results may not necessarily apply to the general population. In addition, men in the study themselves reported their marijuana use, and it is possible that some participants were not truthful about their marijuana use because of the drug's social stigma or illegal status in Massachusetts at the time the data was collected.
Originally published Live Science.