Why Testosterone Levels Have Dropped Precipitously Over History

Why Testosterone Levels Have Dropped Precipitously Over History

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.


While the exact reasons for the decrease in average testosterone levels between generations are unknown, there are several factors that may have contributed to the change.

Some scientists point to increased rates of obesity and reduced smoking, both of which are associated with lower testosterone levels. Other scientists cite environmental factors such as exposure to some chemicals known to be endocrine disruptors. It is unclear what may be the best way to combat the drop in testosterone levels.

Natural declines in testosterone levels

It's no secret that testosterone levels fall naturally with age in men, and, furthermore, testosterone levels have decreased steadily through history, according to researchers from Australia.

Their study of 1,382 men found that men with certain habits and traits had lower levels of testosterone than those without those traits. Additionally, men with chronic health problems experienced greater declines in testosterone levels than those without such issues. These results suggest that natural declines in testosterone levels are a normal part of life.

Studies conducted in the early 2000s have found that the average male in the United States had a testosterone level of 605 nanograms per deciliter at the start of the millennium. Twenty years later, that number dropped by 27 percent. The average testosterone level of a 22-year-old man in 2000 was equivalent to that of a 67-year-old man in 1990. This finding has prompted many researchers to question the role of testosterone in the male body.

Low T symptoms

In general, men experiencing low testosterone levels may experience symptoms like fatigue, weakness, and depression. They may also lose their sex drive. However, this is not a cause for alarm, and it's a normal part of aging. However, it's important to know that testosterone levels may decline over time due to diet and lifestyle factors. Therefore, it's important to talk with your doctor if you have any concerns about the decline of testosterone in your body.


In a study published in the Journal of Biochemistry and Molecular Biology in 2017, Swan and colleagues found that the average testosterone level in western men has fallen by more than five percent in the past 40 years. They found that testosterone levels in men were negatively correlated with serum leptin levels, adjusted for absolute body fat mass. These findings suggest that the decline in testosterone is related to a variety of factors, including obesity and smoking.

While the exact causes of testosterone's decline are unknown, many studies have found a link between the onset of andropause and lower testosterone levels. The decline in men's testosterone levels is linked to a range of adverse health outcomes, including diabetes, impaired glucose tolerance, and reduced bone mass. In men who do not gain weight, testosterone levels decline even more than expected. These findings also suggest that testosterone levels may be related to a lower quality of life and an increased mortality risk.

Inhibition of testosterone by chemicals

Testosterone is a naturally occurring male hormone produced in larger quantities in men than in women. Testosterone plays a number of roles in the body, including initiating the development of male reproductive organs in the fetus, ensuring the production of sperm throughout adulthood, signaling the body to produce new blood cells, and ensuring a man's muscle and bone strength during puberty. In addition to all of these important functions, testosterone also plays a role in the sexual development of boys, regulating the secretion of luteinising hormone and follicle stimulating hormone.

Environmental factors, such as air pollution, can affect testosterone levels. Studies show that men who are exposed to industrial coolants have lower testosterone levels in later life. Exposure to air pollutants and infectious diseases is also linked with lower testosterone levels. To prevent this, you should avoid plastic bottles. And, last but not least, you should avoid smoking and using plastic containers for food. 

Testosterone replacement therapy (TRT)

Inhibition of hormone production by chemicals has led to a dramatic decline in the average testosterone level over history. However, it is important to note that testosterone therapy is not without risks. The FDA has issued several warnings regarding the potential risks of testosterone therapy. In the recent T-Trials study, the authors of the trial compared 6,355 Medicare beneficiaries who had at least one testosterone injection to 19,065 naive men. While the study did not measure the effect of testosterone therapy on mortality, the authors took into account confounding variables and controlled for other medications and treatments. Moreover, the study did not evaluate any testosterone therapies outside of the study protocol.

The use of testosterone therapy for men has increased significantly over the last decade, driven by the growth of direct-to-consumer advertising. With this increased awareness and demand, clinicians have loosened their indications for this treatment. Anti-aging strategies and clinical care centers for men's health have emerged as popular methods of testosterone therapy. The results are encouraging for patients suffering from symptoms related to decreased testosterone levels.

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Effects of TRT on physical and mental performance

Studies involving older men have shown that testosterone therapy does not enhance cognitive function. However, the studies that looked at mild memory impairments showed no significant improvement after testosterone treatment. The long-term effects of testosterone therapies on healthy men are unknown, and physicians are wary of them. Some testosterone product users have sued drug companies for side effects. In the meantime, other studies have reported some mild benefits. Here are some facts you should know before you decide on testosterone therapy for yourself.

One study showed that a moderate dose of testosterone improved verbal memory in elderly men. But a low dosage had no effect. Another study found that androgen deprivation had little to no effect on memory. Fortunately, the estrogen-like hormone estradiol reversed the negative effects of androgen deprivation. However, the study was conducted in animals, and there are ethical issues relating to testing humans.

The effects of testosterone on physical and mental performance depend on their timing and genetics. The timing of the study is vital, as the effects may be different in different populations. Studies on rhesus monkeys have found that testosterone manipulation did not improve spatial and reference memory in these subjects. However, testosterone-induced depression has been associated with improved mood in some men. However, further studies are needed to determine whether testosterone has a positive effect on memory and performance.

Researchers have noted that there is no definitive evidence of a direct relationship between the levels of testosterone and cardiovascular events in men taking TRT. However, other studies have suggested that TRT can improve sexual function and reduce depression. The study also found no significant differences between testosterone replacement and placebo in men. Efficacy of treatment may depend on how the men's overall quality of life is measured and the effects of side effects. For example, testosterone replacement therapy can enhance libido and erectile function.

Is there another solution?

If we consider what could be the cause of a generational decline of testosterone, let's seek to amend that rather than try to find an expensive drug for a shortcut. 

Therefore, let's get more active. Research shows that resistance training can help stimulate hormone production, it's also good for our bone health and muscle development. 

Our forefathers had limited access to highly refined and processed foods that now line the shelves of our supermarkets. They ate more raw foods that included more vegetables and offal (now considered cheap cuts of meat) that are high in nutrients such as iron, zinc, selenium and other vitamins. If you're stuggling to get all the nutrients you need, try a supplement.

Try to use less plastics for food preparation and storage if possible. Opt for glass or metal where appropriate. 

Stress appears to be commonplace, this could be down to a change in working practices and employment structures, it could also be down to the effects of social media.

If so, when you finish work, try to turn off notifications on your devices so you're not reacting to emails or messages that can be dealt with during working hours.

Limit social media use or even exposure to media which is developed to create a reaction and interaction.  


The data and research available associates increasing age with reduced testosterone levels, this is commonly referred to as the andropause. 

However, the data also shows that over time, there has been a generational decline of testosterone. 

There are suggestions for this, it can be the lack of exercise and the increased consumption of processed foods and beverages that do not include all the nutrients we need.

Then there's environmental factors such as chemical exposure from plastics and other personal care products that weren't as commonplace half a century ago. Furthermore, there is a suggestion that stress is also a factor, with things such as social media, being in constant contact with employers and increasing workloads having a detrimental effect on our lives.

While TRT is often touted as a 'cure' there are some benefits to testosterone therapy, but the results are not conclusive. Studies are needed to determine the dosages, duration, and levels of testosterone. In addition, testosterone-induced depression and cognitive impairment are also associated with lower levels of this hormone. 

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