With a Grain of Cannabis

"These findings are not consistent with a deleterious role of marijuana smoking on testicular function as initially hypothesized."
"Whether these findings are reflective of the previously described role of the endocannabinoid system in spermatogenesis or a spurious association requires confirmation in further studies."
New study on pot smoking and testosterone, Harvard University

"We know a lot less than we think we know. These unexpected findings highlight how little we know about the reproductive health effects of marijuana, and in fact of the health effects of marijuana in general."
"[This paper] does not mean that using more marijuana is going to increase sperm counts, or testosterone or your masculinity."
"But who knows -- it may turn out that marijuana is actually positive for sperm production, and we've been getting the answer wrong [up to the present]."
"The problem is we can't tell which of those two interpretations is the correct one."
"Our results need to be interpreted with caution and they highlight the need to further study the health effects of marijuana use."
Dr. Jorge Chavarro, associate professor of nutrition and epidemiology, Harvard University

Photo: Getty

The results of a study undertaken by Dr. Chavarro and his colleagues surprisingly points to a tentative conclusion, that men who have smoked marijuana were imbued with notably elevated sperm concentrations and counts, along with higher testosterone levels, challenging expectations to the contrary, given previous studies' opposite conclusions and generally accepted as fact. Not only did he study conclude that men who had never smoked weed had inferior sperm concentrations and counts, but marijuana users' sperm appears to be of superior grade.

Hitherto studies, most of them with laboratory rats yet several with human males, have posited a link with heavy pot use and a slump in sperm production. Dr. Chavarro's study links casual, light use of marijuana with upgraded sperm count, however. Men smoked, on average, two joints a week with the new study. Dr. Chavarro, in attempting to rationalize his team's findings hypothesizes that males with higher circulating testosterone concentrations might be more likely to smoke pot, along with other "risk-taking behaviours".

On the other hand, indulging minimally in pot might result in sperm production being boosted, skewing the finding that high pot use depresses sperm production to give a green light to random, lesser use of marijuana as a potential bonus. A corollary can be found in alcohol consumption, considered mildly beneficial in small amounts, and hugely detrimental when taken in large proportions.

A widely regarded study that took place in 2014 of close to 2,000 British men found that under age 30 males with fewer than four percent normal sperm almost twice as likely to have used cannabis in the previous three months. This study represented the largest done to date in exploring how common factors in lifestyle can influence sperm morphology.  Researchers found as well that sperm size and shape was degraded in samples taken during summer months.

Overall, the sperm of past and current marijuana users seemed to be of superior quality. Getty Images

In the new study recently published in the  journal Human Reproduction, 1,143 semen samples collected from 662 men enrolled at the Massachusetts General Hospital fertility centre were studied along with blood samples collected from 317 of the men and analyzed for reproductive hormones. On average 36 years of age and mostly Caucasian university educated, just over half reported smoking some marijuana at some time. Of this number, 44 percent were past smokers, and 11 percent current smokers.

Average sperm concentrations of 62.7 million sperm per millilitre of ejaculate linked with men who had smoked pot, in comparison to 45.4 million/mL for men who had never used marijuana. No significant differential in sperm concentration was noted between the two streams, however, and a similar pattern was expressed for total sperm count. Sperm concentration below 15 million/mL reflects a mere five percent of marijuana smokers, the WHO's threshold for "normal" levels, compared with 12 percent of men who had never smoked pot.

Quartz

"As the authors point out, men with higher sperm concentrations are likely to have more testosterone in their bodies and thus may be more likely to smoke marijuana because simply they are willing to take more risks."
"In conclusion, I am not convinced that this paper moves us any further forward in this debate.

"Moreover, nor does it give support to any apparent fertility benefits of smoking marijuana."
"In my opinion, this should be avoided at all costs in any couples trying to start a family."
Allan Pacey , Professor of Andrology,  University of Sheffield, Great Britain