A 2023 study that involved a relatively small sample size of rats found that smoking cigarettes and electronic cigarettes can change the physiology of rat testes.
The findings potentially have implications for humans but, as of this publication, it is unknown how such experiments in rats translate to human health. The researchers concluded that more investigation is needed to determine to what extent e-cigarettes and cigarettes impact human fertility.
In September 2023, social media posts suggested that a study found that vaping could "shrink male testicles and cause sperm counts to plummet." One such example included a post that was shared to X on Sept. 5, 2023:
New study reveals vaping can shrink male testicles and cause sperm counts to plummet. pic.twitter.com/xxqbK8EGyN
— Daily Loud (@DailyLoud) September 5, 2023
Similar claims were also reported on other social media platforms including Instagram and Reddit, as well as in major media publications, such as coverage reported by Forbes, The New York Post, The Daily Mail, among others.
The study that has been cited in the above publications is authentic: It was published in the July-September 2023 edition of the Spanish peer-reviewed journal Revista Internacional de Andrología and was titled, "The effect of smoking and electronic cigarettes on rat testicles." Though it found that smoking cigarettes and electronic cigarettes can change the physiology of testes, as its title implied, the research was conducted on rats – not actual humans – and it's too soon for the results to be extrapolated to humans.
So, while it is true that the findings may have implications for humans, as of this publication, it is unknown how such experiments in rats translate to human health. The researchers concluded that more investigation is needed to determine to what extent e-cigarettes and cigarettes actually impact human fertility.
That being said, other studies have found that vaping and e-cigarettes may have health impacts on male fertility. For example, a 2020 study found that e-cigarette use was associated with lower sperm counts. Similarly, cigarette smoking is associated with lower semen volume and total sperm count, especially in heavy smokers.
Let's take a deeper look at the findings of the 2023 study in question.
E-cigarettes are sometimes used by people who are trying to stop smoking cigarettes, yet the health impacts of their use are not fully understood. To determine the potential ways in which e-cigarettes may impact male fertility, researchers exposed 24 adult male rats – an admittedly small sample size – to e-cigarette aerosol and cigarette smoke.
After this exposure, the researchers tested levels of cotinine, the product formed after nicotine enters the body, in the rats' urine, as well as recorded changes observed in testicular weight, sperm count, and other characteristics that are indicative of testicle health.
Some rats in the cigarette and e-cigarette groups experienced a disorganization of their seminiferous tubules, which are tubes found in the testes where sperm is produced. Sertoli cells – one of the "most important cells for sperm production – were also shown to be altered. In extreme cases, the study authors noted rats had experienced atrophy, fibrosis, and necrosis.
Together, the results suggest that smoking traditional and e-cigarettes can increase oxidative stress, or cell death, which has been linked to tissue and DNA damage. Oxidative stress plays a natural role in the aging process but has also been linked to conditions such as cancer, heart disease, and diabetes.
Morphological changes, or structural alterations in cells related to disease, may also result from the characteristics observed by the researchers, though they concluded that more investigation is necessary to understand not only what these results mean for male fertility, but also how they translate to human health in general.