Testosterone, the male sex hormone, helps regulate heart function and plays a part in sperm production, bone health, energy levels, concentration, and muscle mass. This key hormone plays more of a role in a man’s life than just fueling his sex drive.

Most men experience a natural decline in testosterone as they age, and testosterone supplementation is commonly prescribed to help these men regulate their hormone levels.

But researchers have recently found that it’s not just too little testosterone that’s a bad thing—too much might be, as well.

A new study appearing in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM) found that older men with testosterone levels in the middle tended to live longer.

Testosterone Levels and Longevity
Bu Beng Yeap of the University of Western Australia, based in Fremantle Hospital, Western Australia, and lead author of the JCEM study, said when the body metabolizes testosterone it produces dihydrotestosterone (DHT), a chemical in the body tied to lower risks of ischemic heart disease. He and research colleagues discovered having the ideal amount of testosterone and higher levels of DHT could help men maintain good health as they grow older.

“Older men who had testosterone in the middle range survived longer than their counterparts who had either low or high levels of the hormone,” he said.

Researchers came to this conclusion after conducting a population-based cohort study of 3,690 men between the ages of 70 to 89 in Perth, Australia. The men’s testosterone and DHT levels were measured between 2001 and 2004, and their survival rate was recorded through December 2010.

Researchers found men with the lowest testosterone levels had the highest mortality rate, followed by men with the highest testosterone levels. Overall, men with circulating testosterone levels between 9.8 to 15.8 nmol/L range tended to live the longest.

Other studies have raised cautions about too much testosterone: In 2010, researchers at Boston University halted an inconclusive study of testosterone therapy in older men with chronic health problems because of a higher rate of cardiovascular problems in subjects getting the therapy (compared with those getting a placebo).

“Sex hormones are an important predictor of mortality in older men, but we haven’t determined if treatments to change testosterone and DHT levels can alter these outcomes,” Yeap said. “Additional research into these findings, including randomized clinical trials, could help identify ways to leverage this information to improve health in older men.”