Middle-aged men may suffer more frequently from heart disease than women, but testosterone may not be to blame.
A new Finnish study shows that testosterone may actually help protect men from atherosclerosis (or hardening of the arteries) and reduce their risk of heart disease.
Researchers say the results once again call into question the view that estrogen is good for heart health and testosterone is bad.
Recent studies in older menopausal women have shown that estrogen replacement therapy does not offer the benefits in reducing heart disease risk once assumed that it would, and this study shows that testosterone therapy may not necessarily be as harmful to the heart as previously thought.
Although animal studies have shown that testosterone may have negative effects on heart health, such as altering cholesterol levels, researchers say this study as well as others in humans suggest that the male sex hormone may have potential benefits.
"The evidence overall is starting to show that normal testosterone levels in aging men are good for the heart," says researcher Olli Raitakari, MD, PhD, of the University of Turku in Finland, in a news release.
Testosterone and the Male Heart
In the study, researchers compared the extent of atherosclerosis in 99 generally healthy middle-aged men who had symptoms of andropause (low testosterone), such as fatigue, low libido, and depression, to that found in 140 men with no signs of andropause.
The results appear in the May 17 issue of the Journal of the American College of Cardiology.
Ultrasound testing showed that the thickness of the carotid artery, the main artery in the neck and a measure of the extent of atherosclerosis, was greater in the men with symptoms of andropause compared with the other men.
The thickness of the wall of this artery is a predictor of a higher risk of heart disease. The study showed that the wall thickness increased as testosterone levels dropped. They show a link between increased wall thickness and the levels of another hormone called luteinizing hormone -- a marker for male menopause. Researchers say this is the first study to link atherosclerosis to luteinizing hormone.
New Questions About Testosterone Therapy
Experts say this study and others are challenging the notion that the female advantage in heart disease risk is due to either a protective effect of estrogen or a harmful effect of testosterone.
"This study suggests that higher testosterone levels are associated with less atherosclerosis in the carotid arteries, and that's contrary to what we thought," says Elizabeth Barrett-Connor, MD, of the University of California-San Diego, in the news release. "And on the other hand, most middle-aged men who complain of low libido, fatigue, or the other complaints that go with "andropause" symptoms, don't actually have low testosterone levels."
For example, she points out that only 6 percent of the middle-aged men in this study had both symptoms of andropause and low testosterone levels.
"These results suggest that testosterone is not as bad for your heart as we had thought. Clinical trials of testosterone therapy will be necessary to confirm this idea," says Barrett-Connor, who also wrote an editorial that accompanies the study.
SOURCES: Makinen, J. Journal of the American College of Cardiology, May 17, 2005; vol 45: pp 1603-1608. News release, American College of Cardiology.