Study Challenges Long-Held Beliefs About Cannabis and Male Hormones

Researchers from University of Geneva (UNIGE), in collaboration with the Swiss Center for Applied Human Toxicology (SCAHT), have reported findings that challenge common assumptions about the effects of cannabis on male hormones and fertility.

The study found that cannabis use does not appear to reduce testosterone levels in young men. Instead, it may be associated with increased testosterone production in the testes. However, researchers caution that higher hormone levels should not be interpreted as evidence of improved fertility.

The findings were published in the journal Communications Medicine and are based on an analysis of blood plasma samples from 94 Swiss military conscripts.

In addition, the team identified two previously unrecognized hormonal biomarkers that could potentially help detect regular cannabis use.

Ongoing Debate About Cannabis and Reproductive Health

Previous studies have suggested that cannabis use may reduce sperm count, sperm concentration, and sperm motility. Scientists believe these effects may involve the endocannabinoid system, a network of receptors and signaling molecules found in both the brain and reproductive organs that interacts with sex hormones.

However, research findings have remained inconsistent, particularly regarding cannabis's effects on testosterone.

To investigate further, researchers analyzed steroid hormones in blood samples collected from healthy Swiss men aged 18 to 23 years. The study included 47 confirmed cannabis users and 47 non-users.

Unlike earlier investigations that focused primarily on testosterone, the researchers examined hundreds of hormones involved in endocrine regulation, including androgens, estrogens, and progestogens.

Increased Testosterone Levels

The analysis revealed that cannabis users had approximately 23% higher testosterone levels than non-users.

According to Professor Serge Rudaz, the broader hormone analysis allowed researchers to identify the origin of this increase.

“Our results show that cannabis use is associated with about a 23% increase in testosterone levels in young men. By examining the entire androgen profile, we were able to determine that this increase originates specifically in the testes, while androgen production by the adrenal glands remained unchanged.”

The findings suggest that cannabis may exert a direct influence on the testes, particularly on Leydig cells, which are responsible for testosterone production.

Discovery of New Biomarkers

The expanded hormone analysis also led to the identification of two potential biomarkers of cannabis exposure:

• 11β-hydroxyprogesterone (11B-OHP4);

• 5β-dihydroprogesterone (5B-DHP4).

Both molecules are metabolites derived from progesterone, an important sex hormone.

Researchers found that concentrations of these compounds were substantially higher among cannabis users, raising the possibility that they could serve as indicators of endocrine changes associated with regular cannabis consumption.

Lead author Mathieu Galmiche explained that the discovery highlights the need to investigate hormones that have received relatively little attention in reproductive health research.

No Evidence of Improved Fertility

Despite the increase in testosterone levels, the researchers emphasize that the findings should not be interpreted as evidence of better sperm quality or fertility.

The relationship between testosterone and reproductive function remains complex. One possible explanation is that increased testosterone production may represent a compensatory response to reduced sensitivity of androgen receptors in the presence of cannabis.

Another possibility is that individuals with naturally higher testosterone levels may be more inclined toward risk-taking behaviors and therefore more likely to use cannabis.

Further Research Needed

Although the study suggests that cannabis may influence biological pathways involved in male reproduction, its clinical significance remains uncertain.

The researchers stress that additional studies are needed to determine whether there is a threshold at which cannabis becomes harmful to reproductive health and to evaluate any potential long-term effects.

For now, the findings challenge the long-standing assumption that cannabis use necessarily lowers testosterone levels in young men, while leaving important questions about fertility unanswered.

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