Study: Men's Testosterone Levels Have Halved Over Five Decades

SadaNews - A new scientific study has warned of a significant decline in average testosterone levels among men over the past five decades, a development researchers see as an additional indicator of an emerging crisis affecting men's health and fertility worldwide, amid growing concerns about the impact of modern lifestyles and environmental factors, according to the "Independent".

Testosterone is a cornerstone of reproductive health in men, as its role extends beyond sperm production and regulating sexual desire to influencing muscle mass, bone density, metabolic processes, energy levels, and maintaining psychological stability and mood.

The study relied on a systematic review of six long-term studies that examined hormone levels in men, encompassing data from approximately 118,600 men collected between 1972 and 2019 in five countries: the United States, Israel, Brazil, Finland, and Denmark.

The results showed that the average testosterone levels among men in 2019 had declined by more than 50 percent compared to 1972. Researchers also observed similar indicators of hormone decline across all studies included in the analysis, reinforcing the hypothesis that the decline represents a continuous trend rather than a random fluctuation or a result of differing measurement methods.

The researchers, led by Hagai Levin from the Brown School of Public Health at Hebrew University Hadassah in Israel, stated that the average decline since 1979 has reached about 54 percent, noting that the pace of this decline has accelerated significantly since the beginning of the new millennium.

According to the study, testosterone levels are decreasing at a rate of nearly one percent annually, a rate the researchers describe as alarming due to its potential long-term implications for public health and reproductive capacity.

The researchers believe that obesity and diabetes could be among the main factors associated with this decline. As body fat accumulates, part of the testosterone is converted into estrogen, leading to decreased levels. Insulin resistance and chronic elevated blood sugar levels may also affect the functions of the hypothalamus and pituitary gland in the brain, which are responsible for regulating hormone production.

The study did not dismiss the role of environmental factors, as researchers suspect that hormone-disrupting chemicals found in some household products, including so-called "forever chemicals," may contribute to this decline, along with other factors still under investigation.

These findings support a previous study conducted by the same research team, which concluded that there has been a sharp decline in men's sperm counts over the past four decades, which heightens concerns about declining indicators of male reproductive health globally.

Conversely, experts have warned against using testosterone supplements as a general solution, clarifying that using them without medical necessity may inhibit the natural production of the hormone; the brain responds to elevated levels by shutting down stimulating signals for its production.

The study, titled "Temporal Trends in Total and Free Testosterone Levels (1972 - 2019): A Systematic Review and Analysis of Change Trends," was presented at the annual meeting of the European Society of Human Reproduction and Embryology held in London, but it has not yet undergone peer review, meaning its results are still preliminary and require further scientific scrutiny before being definitively accepted.