Can Smoking Cannabis Affect Your Sperm Count? [New Study]

The answer may shock you!


A new study conducted at Duke University Medical Center has found that regular marijuana use is associated with changes in the genetic profile of sperm. This research is timely, as cannabis legalization is now spreading at an exponential rate, and the majority of regular users are male.

Although the herb is known to have many medicinal benefits and is generally considered safe, there are several side effects associated with smoking weed, and the long-term effects are still unclear. The results of this new study suggest that frequent marijuana use may not be as harmless as first thought, not only for the users themselves but also for future generations.

Duke University Medical Center Study

The study, carried out by researchers Kollins et al. and published in Epigenetics, looked at the effects of THC exposure both in rats and 24 human subjects. They discovered that THC seemed to impact a process known as DNA methylation, which is vital for healthy development. This process was altered in hundreds of different genes, all of which were involved in two particular cellular pathways. The first pathway was associated with ensuring that organs reach their full size, and the second was linked with growth during childhood development.

The researchers compared the sperm of frequent marijuana users with non-marijuana users. Frequent users were defined as having consumed cannabis at least once per week over the past six months, while non-users were defined as having consumed marijuana less than ten times during their lives, and not at all within the past six months.

The results showed that the subjects with higher THC levels in their urine had a higher incidence of genetic changes, suggesting that regular marijuana use could be involved. Although the correlation appears to be clear, we still do not know precisely what these findings mean for men who use cannabis and are thinking about starting a family. Regarding the results of the study, the senior author, Scott Kollins, Ph.D., a professor in psychiatry and behavioral sciences at Duke has stated:

“We don’t yet know what that [the research] means, but the fact that more and more young males of child-bearing age have legal access to cannabis is something we should be thinking about.”

Its small sample size limited the study itself, and there are plans to carry out a larger scale trial in the future. The authors also intend to investigate whether these genetic changes are reversible and to study the effects on the offspring of marijuana users by analyzing blood from newborn babies’ umbilical cords.

In the meantime, the authors advise caution and suggest that men who wish to have children stop using cannabis at least six months before trying to conceive.

Related Research on Marijuana and Genetics

The Duke University study is not the first of its kind, and a similar paper was published in Neuropharmacology in 2015. This research looked at rats who had been exposed to THC during adolescence and then went on to reproduce. The rats were dosed with THC every third day between the ages of 28–49 days. They were then bred, and the brains of their offspring were studied.

Although the offspring of the rats had never been directly exposed to THC, the researchers found that they had changes in a staggering 1027 areas of their brains when compared with control subjects. These changes were especially pronounced in the regions associated with reward-related behavior and neural function. The authors conclude that these changes could increase the risk of psychiatric illness and addiction in the offspring of parents who used marijuana in their teenage years.

Does Smoking Weed Affect Your Sperm Count?

Many people struggle with fertility problems, and there is a myriad of different reasons why these can occur. The effects of infertility can be devastating, and couples who are trying to conceive will want to do everything possible in order to increase their chances of a successful pregnancy. This often includes a barrage of tests along with dietary and lifestyle changes, medication, and possibly assisted reproductive technology such as IVF.

For men who wish to conceive, sperm count is an important factor to consider along with sperm morphology and motility. Every drop of semen contains millions of tiny sperm, and anything below 15 million sperm per milliliter is considered suboptimal for fertility. Morphology means the size and shape of sperm, whether they are healthy, deformed, too big, or too small. Finally, motility refers to the sperms’ ability to move towards an egg and achieve fertilization.

Although the above studies both found a relationship between marijuana use and genetic changes, to learn more about whether smoking weed affects your sperm count, we need to look to a Danish study published in 2015.

A total of 1215 healthy males aged 18–28 years were recruited for the study and asked to fill in questionnaires about their recreational drug use over the past three months. Those who had smoked weed more than once a week in the past three months were found to have a 28% lower sperm concentration and a 29% lower total sperm count than those who had not. Sperm counts were decreased further in those who had also used other recreational drugs to 52% and 55% respectively. The study also found that the participants who smoked marijuana had higher testosterone levels than their counterparts.

Another paper published in 2014 found that marijuana use was a risk factor for poor sperm morphology, along with other lifestyle factors such as alcohol, tobacco, other recreational drugs, and occupation.

All the available research suggests that cannabis has a severe and negative effect on male fertility, but why could this be? The answer could well lie within the endocannabinoid system.

The Endocannabinoid System, Development, and Fertility

The endocannabinoid system has only recently been discovered, but we already know that it is responsible for a great many of our vital biological functions. The endocannabinoid system is made up of receptors known as CB1 receptors, found primarily in the central nervous system and the brain, and CB2 receptors found elsewhere in the body.

These receptors can bind with chemicals known as endocannabinoids, triggering a complex series of reactions throughout the body and brain. These cannabinoid receptors can also be activated by the THC found in cannabis, as its molecules are similarly shaped to the endocannabinoids produced naturally by our bodies.

The endocannabinoid system is responsible for maintaining homeostasis and also plays an essential role in regulating our mood, memory, movement, and thought processes.

In babies and children, the endocannabinoid system also plays an integral part in the development of the brain, central nervous system, and other organs. It controls the hardwiring of nerve cells during fetal development, especially in areas of the brain where CB1 receptors are abundant. These areas include the hippocampus which is responsible for memory and learning, the basal ganglia and cerebellum which control motor function, and the prefrontal cortex, striatum, and amygdala, the emotional centers of the brain.

When the development of the endocannabinoid system is interrupted during a child’s early years, this can lead to problems later in life. These include a higher risk of addiction and developing psychiatric disorders such as schizophrenia.

Apart from being essential for healthy development, the endocannabinoid system also plays a crucial role in male fertility by influencing the hormones that are responsible for testosterone and sperm production. There is also some evidence that there are differences in the endocannabinoid systems found in the sperm of infertile men compared with their fertile peers. All of this indicates that marijuana use can reduce male fertility in more than one way.

Does Smoking Weed Affect Your Sperm Count? Final Thoughts

Current research suggests that smoking weed could have a negative impact on male fertility in several different ways. Firstly, it could reduce sperm count and affect morphology, making it far more difficult to conceive. Secondly, it may cause genetic changes, meaning that the children of regular users are at a higher risk of developmental problems, psychiatric disorders, and addiction.

It is still unclear exactly what long-term risks smoking weed poses to the next generation, and whether any adverse effects can be reversed over time. What is clear is that far more research is needed in order to establish the relationship between cannabis and fertility, and allow people to make informed choices about their lifestyles.

Until more is known for sure about this link, it would be wise for anyone thinking about starting a family, male or female, to quit smoking weed well before trying to become pregnant. Doing this will not only improve your chances of conceiving but also give your children the best opportunity for a healthy, happy life.

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