Men’s Testosterone Levels Have Fallen by More Than Half in 50 Years: What The Guardian Data Shows
The average testosterone level in men has fallen by 54% over the past 50 years. This is reported by The Guardian, citing data presented at the annual meeting of the European Society of Human Reproduction and Embryology in London. The period in question is from 1972 to 2019. According to researchers’ estimates, the decline amounts to more than 1% each year, and after 2000 this process probably became faster. Scientists link this not to one single cause, but to a combination of several factors: obesity, diabetes, metabolic disorders, exposure to household chemicals that may interfere with the hormonal system, as well as climate change.
Time for Action analyzed why the new data from The Guardian has once again sharpened the discussion about male fertility, why testosterone is important not only for reproductive health, and why experts warn against the uncontrolled use of testosterone drugs.
What the studies showed
The data reported by The Guardian is based on a meta-analysis of six previous longitudinal studies. Each of them tracked testosterone levels in men over a long period and included at least three time points for comparison. In total, the analysis covered data from 118,593 people from Israel, the United States, Brazil, Finland and Denmark. The observation period was from 1972 to 2019. Each of the six studies separately showed a decline in testosterone levels. After combining the data, the overall decline was estimated at 54%. This figure became the main signal for a new wave of discussion about male reproductive health. Professor Hagai Levine of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Israel said that this is not a random deviation.
“We saw an over 50% decline in total testosterone over this time period,” he said.
“It reflects a more than 1% decline each year, so this is not a fluke, this is not a statistical error. It’s very strong trend.”
Why this is not only a fertility issue
Testosterone is often perceived as a hormone connected mainly with sexual desire and the ability to conceive. But its role is much broader. It is involved in sperm production, affects libido, muscle mass, bone density, energy levels, metabolism and mood. Therefore, a long-term decline in testosterone may be a sign not only of reproductive problems, but also of broader disturbances in men’s health. This is exactly what Professor Levine emphasizes. According to him, reproductive health may be an important indicator of the general condition of the body.
“I think that we have a major crisis in male reproductive health and it’s currently not given enough attention,” he said.
“Reproductive health is a very important signal of general health,” said Levine.
Obesity and diabetes as part of the problem
One of the clearest factors that may affect testosterone levels is the deterioration of metabolic health. The Guardian notes that rising levels of obesity and diabetes are likely to play a role in this process. Obesity is closely associated with lower testosterone levels. Excess fat tissue can increase the conversion of testosterone into estrogen. This does not explain the whole picture, but it may be a significant part of the answer. Levine acknowledges that a substantial share of the decline can be linked specifically to obesity and metabolic syndrome.
“If I had to guess – and it’s an educated guess – I would say that maybe one quarter to one half of the decline would be explained by obesity and metabolic syndrome,” Levine said.
This is an important clarification. In the studies included in the meta-analysis, age was taken into account, but obesity was not controlled separately. Therefore, part of the overall decline may have been shaped by changes in the health of the population over recent decades. In other words, researchers see a sharp fall in testosterone, but the causes of this process require careful explanation. The decline cannot automatically be reduced only to chemicals, climate or lifestyle. More likely, it is a combination of several factors.
Household chemicals and the environment
The research team also suggests that environmental factors may affect testosterone levels. Among them are chemicals that disrupt the endocrine system, air pollution and global heating. Such substances may be found in various household products. Their danger lies in the fact that they can interfere with the body’s hormonal processes. At the same time, The Guardian notes that studies on the impact of air pollution and endocrine-disrupting chemicals often produce inconsistent results. That is, scientists consider these factors possible, but so far they do not have equally convincing evidence for each of them. Despite this, Levine calls for not waiting for absolute certainty when it comes to potentially dangerous substances.
“The level of certainty that we need is not 95%,” he said.
“We should find better ways to prevent exposure of the general public to hazardous chemicals. And we don’t do it well enough at the moment.”
This position effectively means applying the precautionary principle. If there is a suspicion that certain substances may harm the hormonal system, their impact on the population should be reduced before a full body of evidence is obtained.
Why the scientific debate continues
Claims about the deterioration of male fertility have been causing debate for years. Earlier, the same team of researchers said that sperm counts had sharply declined over the past 40 years. These findings attracted significant public attention, but some scientists treated them cautiously. The new work on testosterone adds another indicator to this discussion. If the level of a key male hormone has indeed been falling for decades, this may point to broader problems in reproductive health. Professor Channa Jayasena of Imperial College London, a consultant in reproductive endocrinology, called the new data an important reality check.
“The fact that these studies have been done over several periods in history makes me actually convinced,” he said.
“I do think male reproductive health is declining and appears to have been declining over time.”
His assessment shows that some specialists no longer perceive these data as a separate signal. For them, this is part of a longer trend that requires attention from medicine and public health systems.
Why testosterone supplements may be a risk
A separate problem is the rapid promotion of testosterone drugs on social media. Around conversations about “low testosterone,” a simple commercial offer is often built: take a test, get a drug and “restore the norm.” But experts warn that this logic may be dangerous, especially for men who plan to have children. Professor Allan Pacey, a professor of andrology at the University of Manchester, who was not involved in the study, drew attention precisely to this risk.
“The solution that’s being promoted is that we give you testosterone,” he said.
“But if you give a man testosterone, you switch off his sperm production. I’ve seen that in the clinic.”
This is one of the most important practical conclusions. Low testosterone does not mean that a man automatically needs hormonal drugs. Taking testosterone on one’s own may not improve fertility, but instead suppress sperm production. Therefore, any decisions about hormone therapy should be made after a medical examination. What matters is not only the numbers in the tests, but also the cause of the decline, the general state of health, metabolic indicators and a man’s reproductive plans.
What the fall in testosterone means for society
The data reported by The Guardian does not provide a simple answer to why testosterone levels have fallen so sharply. But it shows that male reproductive health needs much more attention. The problem is not limited to individual habits. It is connected with nutrition, rates of obesity and diabetes, exposure to chemicals, environmental quality and access to correct medical information. At the same time, these data should not be turned into a reason for panic. The researchers themselves acknowledge the limitations of the analysis. In particular, obesity was not controlled separately, although it is strongly associated with low testosterone. Also, not all environmental factors have an equally clear evidence base. But the main signal is already clear: male reproductive health cannot be reduced to the private problem of an individual person. If the decline in testosterone is confirmed on large datasets and continues for decades, this is a public health issue. What is needed is not quick recipes from social media, but prevention of obesity and diabetes, quality diagnostics, caution with hormonal drugs and a more serious attitude toward the chemicals with which people come into contact every day.
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