Men’s average testosterone levels halved in 50 years, scientists report
7 reported2 unconfirmed
Scientists presented data at the annual meeting of the European Society of Human Reproduction and Embryology in London on Tuesday showing that total testosterone levels in men declined by 54% between 1972 and 2019. The research, led by Prof Hagai Levine of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Israel, combined six previous longitudinal studies tracking testosterone from Israel, the US, Brazil, Finland and Denmark, including data from 118,593 individuals. The decline appeared to accelerate after 2000, according to the researchers. Rising obesity and diabetes are expected to play a part, but the team also suggested environmental factors such as endocrine-disrupting chemicals and global heating could be factors. The findings contribute to a debate about whether male fertility is in decline, with previous work by the same team concluding sperm counts have steeply declined over the past 40 years. Some scientists expressed confidence in the trend, while others cautioned that obesity and diabetes could account for the entire decline and that more research is needed on environmental factors.
What’s reported
Total testosterone levels in men declined by 54% between 1972 and 2019, according to data presented at the European Society of Human Reproduction and Embryology annual meeting in London on Tuesday.
The meta-analysis combined six previous longitudinal studies with at least three time points each, including data from 118,593 individuals from Israel, the US, Brazil, Finland and Denmark.
The decline appeared to accelerate after 2000.
Rising obesity and diabetes are expected to play a part; environmental factors such as endocrine-disrupting chemicals and global heating were also suggested.
Prof Hagai Levine stated: “We saw an over 50% decline in total testosterone over this time period.”
Prof Channa Jayasena of Imperial College London said the observations should act as “an important reality check” and that he is convinced male reproductive health is declining.
Prof Allan Pacey of the University of Manchester noted concern about promotion of testosterone supplements on social media, saying giving testosterone can suppress sperm production.
Open questions
The exact contribution of obesity and diabetes versus environmental factors to the testosterone decline is unclear.
Which specific environmental factors (e.g., air pollution, endocrine-disrupting chemicals) are involved remains uncertain, with studies producing inconsistent results.
Key figures
Prof Hagai Levine, Hebrew University-Hadassah Braun School of Public Health and Community Medicine, Israel
Prof Channa Jayasena, Imperial College London and consultant in reproductive endocrinology
Prof Allan Pacey, professor of andrology at the University of Manchester
Robert F Kennedy Jr, US health secretary (mentioned as describing male fertility decline as an “existential problem”)
Sources: The Guardian
