Men should stop using cannabis for at least six months before they hope to father children, scientists have warned.
Researchers took sperm samples from 12 men who used the drug at least once a week and found it altered the DNA of their swimmers. Changes were found in the DNA that codes for both growth and organ development, with such genetic mutations even being linked to cancer.
Although unclear whether these changes may be passed on to their children, the scientists behind the study have advised men to assume the worst. The study, published in the journal Epigenetics, was led by Dr. Susan Murphy at Duke University.
In the first study of its kind, sperm samples were taken from healthy men – aged 18 – 40 years – who claimed to use cannabis at least once a week for the past six months.
These samples were compared against the sperm of 12 men who had not used cannabis in the past six months and had used it a maximum of ten times throughout their lives. Urine samples confirmed their marijuana use.
Results supported past findings that cannabis users have significantly lower sperm concentrations than non-users. When the DNA of the participants’ sperm was analyzed, the researchers found cannabis is linked to genetic changes.
It is unclear whether these changes influence a man’s fertility or get passed on to his children – the affected sperm may not even be healthy enough to fertilize an egg. But the affected genes are linked to organ development and growth, and have been associated with cancer if they become dis-regulated.
Although concerning, the researchers note not many men were included in their study and that other factors – including nutrition, sleep and alcohol – can also affect sperm.
They plan to carry out a larger trial that also investigates if the effects of cannabis on sperm get reversed in cannabis users if they stop taking the drug. The scientists also hope to test the umbilical cord blood of babies born to fathers with cannabis-alerted sperm to determine if any DNA changes are passed down.
More than 180million people use cannabis around the world, the authors wrote. The drug is legal for either medical or recreational use in more than half US states.
Among 26 – 34 year old men, 20.6 per cent admitted to using cannabis in the past year, The National Survey on Drug Use and Health reported in 2015.