The team from the Polish Academy of Sciences' Institute of Human Genetics in the western city of Poznań confirmed this link in a group of professional drivers.
The researchers used their findings to launch a new public awareness campaign called #NieGrzejJajek. The slogan literally means “don't heat your balls” and is aimed at encouraging men to protect their fertility.
Polish scientists point out that male fertility is a global concern. Sperm quality has been declining worldwide for more than 60 years, and male factors are estimated to contribute to about half of all infertility cases.
Experts say around 50 million couples worldwide struggle with infertility, including more than 1.5 million in Poland.
The study was led by Monika Frączek, a professor at the Institute of Human Genetics, in cooperation with the Pomeranian Medical University in Szczecin, northwestern Poland, and the Ivan Franko National University of Lviv.
Lifestyle changes may be enough to improve semen quality: lead researcher
Summing up the research, Frączek said that in many cases a change of lifestyle is enough to improve semen quality and increase a man’s chances of becoming a father.
The team examined semen samples from more than 300 men of reproductive age across five groups, including fertile men, infertile men with no heat exposure, men with testicular conditions that raise local temperature, and professional drivers who spend many hours sitting.
This design allowed the researchers to compare clinical causes of increased testicular temperature with environmental ones.
The key mechanism identified by the scientists is so-called oxidative stress. This is an imbalance between reactive oxygen molecules, often called free radicals, and antioxidants, which are protective substances.
In semen, antioxidants in the fluid part usually neutralize these reactive molecules. When the scrotal area is warmed for long periods, sperm metabolism speeds up, sperm cells produce more reactive oxygen species, and the supply of antioxidants is used up more quickly.
Once this protection is exhausted, the reactive molecules begin to damage sperm DNA and trigger cell death, which lowers sperm quality.
Frączek explained that the position of the testicles outside the abdominal cavity is a natural cooling system. Normal sperm production requires testicles to stay about two degrees Celsius cooler than the rest of the body, at roughly 34.5 to 35 degrees.
“If this delicate thermal balance is regularly disturbed, semen quality falls,” she said.
According to the study, both long sitting and certain testicular diseases, such as varicose veins of the spermatic cord, raise temperature in the scrotum.
The researchers were the first to show a strong correlation between increased production of oxygen free radicals in sperm cell mitochondria and the degree of sperm DNA fragmentation in professional drivers.
Frączek called this an important proof that a common environmental factor, long hours in a seated position, can cause changes in sperm comparable to those seen in varicose veins of the spermatic cord, which are among the most frequent causes of male infertility.
The scientist noted that excessive warming of the testicles happens in many ordinary situations that men rarely connect with fertility problems. These include hot baths, regular sauna visits, keeping a laptop on the lap, tight underwear, especially made of synthetic fabrics, very intense exercise and long car journeys.
As a practical measure, she recommended that drivers on long routes take short breaks at least every two hours, get out of the car and walk for a few minutes to let heat dissipate in a natural way. This, she said, requires awareness more than sacrifice and can help protect fertility.
She added that even a single 20-minute sauna session can lead to a fall in sperm count within a few days of exposure.
At the same time, she stressed that heat-related fertility problems are in large part reversible if the risk factor is removed.
A full cycle of sperm renewal takes around 72 to 74 days, so couples trying for a child are advised to limit activities that raise scrotal temperature during that period.
Frączek also reminded people that obesity, especially abdominal obesity, is an important risk factor for male infertility. Excess fat tissue around the abdomen stores heat and makes it harder for the testicles to cool, which adds to the effect of other warming factors.
The team’s findings open new diagnostic and treatment avenues for male infertility.
They have also provided the scientific basis for the #NieGrzejJajek social campaign, prepared by the NGO Nasz Bocian (Our Stork), a Polish patient organization that supports couples dealing with infertility and seeking to adopt children.
The Institute of Human Genetics serves as the campaign's expert partner, and the Polish Society of Andrology, a professional body for specialists in male reproductive health, has also supported the initiative.
(rt/gs)
Source: naukawpolsce.pl