Studies have shown that men who receive testosterone therapy experience an increase in energy, drive and sexual function, are more mentally alert and have stronger bones and better body composition. A new study has emerged indicating that testosterone therapy may also decrease the risk of heart disease and stroke in men.

The largest observational study ever performed to assess testosterone levels and its impact on men was recently published in the European Heart Journal. As part of their study, researchers evaluated 83,000 men from 140 hospitals in the Veterans Affairs Health System who also received at least 14 years of follow up.

Men who received treatment experienced a 47 percent decrease in death, an 18 percent reduction in heart attacks and a 30 percent decrease risk in stroke. These numbers were much higher than what researchers had anticipated.

"It is the first study to demonstrate that significant benefit is observed only if the dose is adequate to normalize the total testosterone levels," stated Dr. Rajat Barua, the paper's corresponding author and his coauthors . "Patients who failed to achieve the therapeutic range after testosterone replacement therapy did not see a reduction in [heart attack] or stroke and had significantly less benefit on mortality."

To qualify, men had to have low testosterone levels to begin with—around a T level less than 300. The normal testosterone level for men sits between a T level of 500 and 1000. Researchers found that men who received therapy, but did not reach a T level of 500 were much more susceptible to being diagnosed with heart disease and stroke than men who had achieved those levels.

Each year around 610,000 people die of heart disease in the United States, and more than half of those victims are men. In fact, heart disease is the leading cause of death of all men in the U.S.

Stroke is the fifth leading cause of death in the U.S., and about 40 percent of victims are males. Of the 795,000 people who suffer from strokes each year, most were first time attacks, and nearly three-quarters of all strokes occurred in people over the age of 65.

The study, however, was not without bias. It was not randomized and did not address an older study which had indicated that testosterone therapy actually increased cardiovascular activity in elderly, inactive men.  Because there has been some controversy as to whether increasing testosterone levels help or hurt older, inactive men, the researchers will continue studying how the therapy affects older men.

While more testing is needed, the findings are significant. Heart disease, stroke and heart attacks are all leading causes of death in U.S. men. The new study sheds light on alternative practices to help prevent these occurrences.