CLAIM:
The post claims that microplastics accumulating in the male reproductive system can cause testicular inflammation, lower testosterone levels and reduce sperm count, thereby harming fertility. It further claims that reducing plastic exposure and following a sauna-based "detox" protocol can remove most microplastics from sperm and improve reproductive health.
FACT:
Studies have detected microplastics in human testes and semen, and animal and observational studies suggest they may adversely affect sperm quality and reproductive health. However, there is currently no conclusive evidence that microplastics directly cause infertility in men, nor is there any scientific proof that sauna-based "detox" protocols can remove microplastics from sperm or improve fertility. In fact, prolonged heat exposure may itself impair sperm production and quality.
In a viral LinkedIn post, Bryan Johnson, a tech entrepreneur and longevity enthusiast known for spending millions of dollars on his anti-ageing regimen and his "Blueprint" project aimed at slowing biological ageing, claimed that microplastics accumulating in the male reproductive system are damaging fertility and that lifestyle measures, including sauna sessions, can help remove them.
In the video, Johnson reacts to a clip of a woman saying, "I don't understand why I can't get pregnant," before images of plastic containers appear on screen. He argues that infertility has long been viewed as a women's issue and says men also need to take responsibility. "Men, you have microplastics in your balls. It's wrecking your fertility. I can help," he says.
Johnson claims that microplastics can lead to testicular inflammation, reduced sperm count and lower testosterone levels. He advises reducing exposure by avoiding heating food in plastic containers, steering clear of plastic cutting boards and polyester clothing, and using reverse osmosis or carbon-block water filters to limit microplastics in drinking water.
Johnson further claims that he was able to eliminate "85% of microplastics" from his sperm through a detox protocol involving daily sauna sessions at 200°F, wearing 100% cotton clothing and applying ice to the testicles during the process. "If you don't ice the boys, the sauna will actively hurt your fertility," he says, adding, "Men, we have been putting the blame of infertility on women for too long. Have some balls and do your part."
The post has sparked widespread discussion online, with many users questioning whether microplastics can indeed impair male fertility and whether saunas or other interventions can effectively remove them from the body.
How accurate are Bryan Johnson’s claims about microplastics and male fertility?
The available evidence supports concerns that microplastics may adversely affect male reproductive health, but much of the mechanistic evidence comes from animal studies. Scientists agree that more large-scale human studies are needed before firm conclusions can be drawn about the extent to which microplastics contribute to infertility in men.
A 2024 study examined testicular tissue from 23 men and 47 dogs using pyrolysis-gas chromatography/mass spectrometry to identify different plastic polymers. Researchers found microplastics in every sample analysed, with polyethylene (PE) being the most abundant. The study also observed negative correlations between certain plastics, particularly PVC and PET, and testicular weight in dogs. The authors noted,"These findings highlight the pervasive presence of microplastics in the male reproductive system in both canine and human testes, with potential consequences on male fertility."
At the same time, the researchers stressed that their findings should be interpreted cautiously. "The observed associations between microplastic presence and sperm parameters do not imply causality," they wrote, noting that the human samples were not representative of the broader population and that larger studies are needed to determine whether current levels of microplastics affect male reproductive function.
Further evidence came from another 2024 cross-sectional study involving 113 men from three regions in China. Researchers detected microplastics in all semen and urine samples, with most participants exposed to three to five different polymer types. They found that exposure to polytetrafluoroethylene (PTFE), commonly used in non-stick cookware, was associated with poorer semen quality. The analysis showed that each additional type of microplastic exposure was linked to reductions in sperm count, concentration and progressive motility. The authors concluded that their findings "highlight the potential reproductive health risks posed by microplastic contamination, particularly PTFE," while emphasising that further studies are needed to understand the underlying mechanisms and long-term effects.
Adding to this, a 2025 review examining the link between microplastics and infertility noted that these particles have already been detected in blood, placental tissue and seminal fluid, suggesting continuous human exposure. Drawing on animal studies and the limited human data available, the authors reported that microplastics may contribute to reproductive dysfunction through oxidative stress, cellular apoptosis and hormonal disturbances. They concluded that "while direct evidence in humans is limited, the presence of MPs in human reproductive tissues and their overlap with affected mechanisms provide a solid basis for future research."
More recent animal studies have provided insights into how microplastics may damage reproductive tissues. A 2026 study exposing male rats to low doses of polystyrene microplastics found dose-dependent declines in sperm count and motility, increased sperm abnormalities and reduced testosterone levels. The particles were detected in testicular tissue at higher doses, and the researchers observed inflammation, oxidative stress, mitochondrial dysfunction and structural damage to the testes. Summarising their findings, the authors wrote that exposure to polystyrene microplastics "impaired semen quality, disrupted sex hormones, and induced marked testicular histopathological damage in adult male rats."
Similarly, another 2026 review highlighted that microplastics can enter the body through food, air and skin contact and may interfere with multiple stages of reproduction. The review states that these particles can "affect the structure and function of the testis," disrupt spermatogenesis and alter hormone production. However, the authors stressed that human-based studies are urgently needed to establish whether these mechanisms translate into infertility in real-world populations.
Experts take
Dr Santhosh Raj, Consultant – General & Laparoscopy Surgery, Male Infertility & Sexual Health, Motherhood Hospitals, Banashankari, Bengaluru, said that the presence of microplastics in the male reproductive system has been established, but their direct role in causing infertility in humans remains unproven.
"Although there is clear evidence that microplastics have been found in testicular tissue and semen samples from men, science does not yet have proof that these particles directly lead to testicular inflammation, low sperm production, reduced testosterone levels or infertility," he said.
Dr Raj explained that most of the available evidence on the harmful effects of microplastics comes from animal experiments and cell culture studies. While some human studies have found that men with higher levels of microplastics in their reproductive tract tend to have poorer sperm parameters, he cautioned against interpreting these associations as proof of causation. "Men are simultaneously exposed to numerous chemicals and lifestyle factors, including stress and diet, making it difficult to isolate the specific effect of microplastics at present," he noted.
Addressing sources of exposure, Dr Raj said that everyday plastic use contributes significantly to the body's microplastic burden, though not all sources carry the same risk. According to him, heating food in plastic containers and using plastic cutting boards are among the major contributors, as these processes can release millions of microscopic plastic particles. He added that bottled water and unfiltered tap water are also important routes of exposure.
However, he stressed that there is currently no clinical evidence showing that reducing plastic use or installing water filters directly improves sperm count or testosterone levels. "From a physiological standpoint, reducing overall toxin exposure makes sense, and limiting plastic use may also decrease exposure to plastic-related chemicals such as phthalates and bisphenols," he said. At the same time, he pointed out that no studies have yet determined how quickly the human body can eliminate microplastics once exposure is reduced.
Commenting on Bryan Johnson's claims about sauna-based detoxification, Dr Raj said there is no scientific basis for the assertion that such methods can remove 85% of microplastics from semen. "There is simply no published evidence to support this claim. Microplastics do not have the biological ability to leave the body through sweat or semen in response to heat exposure," he said.
He further warned that frequent exposure to high temperatures may actually be harmful to male fertility. "The testes are located outside the body because sperm production requires a temperature lower than core body temperature. Excessive heat exposure, such as repeated sauna sessions, can cause thermal damage, leading to lower sperm counts, reduced sperm motility and even damage to sperm DNA," Dr Raj said.
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS
