NEW YORK (Reuters Health) - Although use of testosterone supplements may increase lean body mass and reduce fat mass in older men, it does not improve functional mobility or mental ability, according to a report in the Journal of the American Medical Association for January 2.
The study involved 237 healthy men between 60 and 80 years old who were randomized to receive testosterone or placebo pills twice daily for 6 months. All of the men had low normal testosterone levels. A total of 207 men completed the study.
Although lean body mass rose and fat mass fell in the testosterone group relative to the placebo group, this did not translate into improved functional mobility or muscle strength, Dr. Marielle H. Emmelot-Vonk, from University Medical Center Utrecht in the Netherlands, and colleagues note in their report.
Likewise, no significant changes in cognitive function or bone mineral density were noted with testosterone use.
Testosterone had mixed metabolic effects. Testosterone supplementation enhanced insulin sensitivity -- meaning the body responded more efficiently to the effects of insulin -- but also led to a drop in "good" HDL cholesterol.
Moreover, by the end of the study, 47.8 percent of testosterone-treated men had metabolic syndrome compared with 35.5 percent of those given placebo. Metabolic syndrome is an increasingly common condition characterized by a clustering of risk factors such as high blood pressure, obesity, high blood sugar and low HDL cholesterol that raise the risk of heart disease, diabetes and stroke.
Testosterone use also had little effect on quality of life, the report indicates.
"This study is, as far as we know, the largest study of testosterone supplementation with the most endpoints and a randomized, double-blind design," the investigators state.
"The findings in this study do not support a net benefit on several indicators of health and functional and cognitive performance with 6 months of modest testosterone supplementation in healthy men with circulating testosterone levels in the lower range."
SOURCE: Journal of the American Medical Association, January 2, 2008.