Nog even een stukje dat ik vond:
Marijuana and "testosteron">Testosterone
A brief report concerning the appearance in gynecomastia in three male pot smokers published in 1972 sparked a number of subsequent studies that examined the relationship between marijuana use and "testosteron">testosterone levels. Gynecomastia, or “male breasts,” however, is not a common side effect encountered with marijuana use.
Instead, the condition is usually the result of an imbalance between "testosteron">testosterone and estrogen in men, with something causing an increase in the latter. Since marijuana has no estrogenic activity,
it isn’t likely to cause this condition.
Even so, animal studies clearly point to an inhibitory effect of marijuana on both "testosteron">testosterone and luteinizing hormone (LH) production. LH is the pituitary hormone that governs endogenous "testosteron">testosterone synthesis in men. When it comes to humans, though, things are far less clear.
Most studies that have examined human marijuana use haven’t shown any significant effect on "testosteron">testosterone levels in normal men. A 1983 study, however, did find depressed "testosteron">testosterone levels after subjects smoked just one joint, with the effect lasting 24 hours. A 1984 study found that pot not only inhibited "testosteron">testosterone but also lowered prolactin, thyroid and growth hormone. It did that by altering the expression of brain substances that govern hormone release.
Nevertheless, a 1989 study gave 17 male volunteers both high and low doses of THC and then tested their hormonal responses. The results showed no hormonal or immune parameters affected by either a high or low dose of THC. Notably,
both "testosteron">testosterone and cortisol were examined, indicating that pot doesn’t produce catabolic effects in muscle through increased cortisol release.
Based on the majority of studies that have looked at the effects of pot on "testosteron">testosterone levels, it appears that the drug has little or no effect on this hormone in humans. One study that examined Jamaican pot smokers, however, did find a significant decrease in active thyroid hormone in the blood,
although the men showed no apparent thyroid dysfunction. Significantly, the men also showed normal "testosteron">testosterone levels despite smoking an average of seven to eight joints a day.
BRON
Dus Cannabis heeft geen invloed op het mannelijk hormoon testosteron en zo dus spiergroei