Weed might affect your swimmers. According to a new study by researchers at the University of Copenhagen, smoking cannabis more than once a day may lower a man's sperm count by about a third.
On average, men who smoked more than once a week had sperm counts 29 percent lower than those who did not smoke or used the drug less often. Sperm concentration — yes, it's different than sperm count — in frequent smokers was also 28 percent lower.
Sperm count is the product of the sperm concentration (million per milliliter) multiplied by the sample volume (milliliters). Together, these two values reveal how many total sperm are in ejaculate.
While inconclusive, researchers say marijuana use may decrease sperm count and concentration due to THC's interaction with certain receptors in the testes. The study was published Aug. 16 in the American Journal of Epidemiology.
Researchers analyzed semen and blood samples alongside a physical evaluation and self-reported drug use from 1,215 Danish men ages 18 to 28. Men were recruited between 2008 and 2012 while attending a compulsory medical examination to determine their fitness for military service.
Participants' drug history with amphetamines, cocaine and ecstasy also were reported. About 45 percent of the men had smoked weed in the past three months and about 10 percent of men had used marijuana in addition to other recreational drugs.
Men who smoked weed and used other drugs had sperm counts 55 percent lower and sperm concentrations 52 percent lower than men who hadn't used the drugs. Participants who had smoked cannabis in the past three months were also more likely to smoke cigarettes and drink more alcohol and caffeine than those who had not.
"We cannot exclude the possibility that the men who used marijuana generally have an unhealthier lifestyle and health behavior, which may also affect their semen quality and hormone levels," researchers told the science news website LiveScience. ♦