A smattering of studies have indicated that marijuana is no good for sperm. Now, research out of Harvard turns that narrative on its head, finding that men who have partaken have higher sperm counts than men who never have. To get there, lead author Feiby Nassan and her team studied 662 men, all of whom were seen with their partners at the Massachusetts General Hospital Fertility Center between 2000 and 2017. In addition to providing a total of 1,143 semen samples, they answered questions about previous marijuana use. About 55% said they had smoked at least 2 joints in their life; the rest said they had never smoked. The team found those who had smoked pot had sperm concentrations of 62.7 million per milliliter, compared to about 45.4 million per milliliter for those who had not. "A similar pattern was observed for total sperm count," per the study in Human Reproduction.
Quartz adds there was more pot-friendly news when looking at the concentration set by the World Health Organization as "normal": 15 million per milliliter. Only 5% of those who had smoked didn't meet that threshold; 12% of men who never had were below it. Nassan cautioned that the research unearthed only correlation, not causation, and she shared some thoughts: It's possible that the detrimental effects hold true for frequent smokers, which is what previous studies have tended to look at. The habits of her large group ran the gamut, with 80% of those who had smoked reporting they don't currently smoke. "An equally plausible interpretation is that our findings could reflect the fact that men with higher testosterone levels are more likely to engage in risk-seeking behaviors—including drug use," she says in a press release. (Could edible pot calm tummy troubles?)