Men's testosterone levels have halved over 50 years, study finds

Average testosterone levels in men have dropped by roughly half over the past 50 years, according to new research.

Testosterone, the primary male sex hormone, regulates sperm production and libido while also building muscle mass and bone density. It also affects metabolism, mood and energy levels. The findings have prompted warnings that men are facing a reproductive health crisis.

The research was presented Tuesday at the annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) in London, according to the Guardian. Researchers said average testosterone levels in men fell 54% between 1972 and 2019.

The study analyzed data from 118,593 men from Israel, the United States, Brazil, Finland and Denmark.

Researchers said rising rates of obesity and diabetes were driving the sharp decline in testosterone. They also said endocrine-disrupting chemicals found in a range of household products, as well as environmental factors such as global warming, may have contributed to the drop.

Hagai Levine, a professor at the Hebrew University of Jerusalem who took part in the study, said men's reproductive health was facing a serious crisis, with testosterone levels down more than 50%, yet the issue was not receiving adequate attention.

"This study shows testosterone levels are declining by more than 1% per year," Levine said, adding that the trend was "not a coincidence or a statistical error, but a very strong pattern."

As awareness of declining testosterone levels grows, concerns have emerged over a surge in advertisements for testosterone supplements circulating on social media and other platforms.

Allan Pacey, a professor of andrology at the University of Manchester, warned that the solution promoted in such advertisements — testosterone injections — could backfire. "If you give a man testosterone, it can stop sperm production. I've seen cases of that in my clinic," he said.