Studies show that men who consume marijuana are more likely to produce semen with a lower concentration of sperm, known as low sperm count, than those who abstain. According to new research from Duke University School of Medicine in North Carolina, smoking cannabis may have an even bigger impact on sperm than previously thought.
The study aimed to learn more about the reproductive effects of a father’s exposure to tetrahydrocannabinol (THC), the most abundant psychoactive cannabinoid in marijuana, and subsequently how it affects embryo development and the lifetime health of the offspring. Samples from both lab rats and humans were used and compared in the research, and the results from both were similar. The sperm from subjects with higher levels of THC in their urine had more pronounced genetic changes.
Following the study, Duke Health announced that “exposure to cannabis alters the genetic profile of sperm,” but “whether genetic changes can be reversed or are passed on to children is still unknown.” The research paper, “Cannabinoid exposure and altered DNA methylation in rat and human sperm,” was published in the journal Epigenetics on December 19, 2018.
Epigenetics explores the biological mechanisms in DNA that turn genes on and off. THC doesn’t mutate the sperm itself, but it may change the way the genes that are passed on to children are regulated and expressed. Researchers believe this information is significant for men of childbearing age because if a child is conceived from a sperm that was altered by exposure to THC, it may impact the development of the child. It is not yet known whether a THC-altered sperm is even capable of fertilizing an egg.
The research team at Duke Health plans to increase the sample size for future studies to learn more about how THC changes the genetic profile of sperm. “In the absence of a larger, definitive study, the best advice would be to assume these changes are going to be there,” said lead author Susan K. Murphy, Ph.D. “We don’t know whether they are going to be permanent. I would say, as a precaution, stop using cannabis for at least six months before trying to conceive.”