Researchers from Duke University Medical Center have found that Tetrahydrocannabinol (THC), an active compound in cannabis, affects the genetic profile of sperm.
The study is based on a very small sample of men, and whether this effect is positive or negative is still yet to be discovered. Also, scientists do not know if the effects are permanent.
But the paper, published in the academic journal Epigenetics, does bring to light pertinent questions surrounding marijuana use.
There is estimated to be more than 180 million marijuana users in the world today, and cannabis is rapidly being introduced into many products in legal markets, including soft drinks, beer, vape pens and creams.
Duke University’s research was conducted on men and rats. Scientists first compared the sperm of two groups of rats: one group had been given tetrahydrocannabinol (THC), and the rest had not. Similarly, the scientists compared the sperm of 24 men: one group of men had smoked marijuana weekly, the other group had consumed marijuana no more than ten times in their life and not used the drug in the past six months.
In both rats and humans, researchers found marijuana had reprogrammed their sperm genes.
Specifically, it affected many different genes involved in two different pathways (a set of genetic instructions). One pathway has to do with regulating organ size, and the other plays a role in cancer and suppressing tumours.
The team suggests these alterations could change over time and may have an impact on successive generations.
“Because sperm maturation is a continual process throughout the adult male’s life, exposures like cannabis could have an impact on the integrity of the sperm methylome, with implications for heritability of such alterations by subsequent generations,” the study authors write.
Scientists are just scratching the surface of marijuana. They agree that more studies involving a larger group of subjects are necessary to further understand how exactly THC affects sperm cells in the long run, and what those changes may entail.
“Our work and others have shown that cannabis use lowers sperm concentration and this study, for the first time, suggests that it may also alter the genetic profile of sperm cells,” Scott Kollins, one of the authors of the study, told Inverse.
“We do not yet know what the implications of this latter finding are.”
Although the extent of the changes are uncertain, lead author Dr Susan Murphy recommends any fervent marijuana user who wants to be a father should stop consuming the drug for at least six months before trying to conceive.