Men's testosterone levels drop as they age. Declining testosterone is linked to loss of muscle mass, loss of muscle strength, gain of abdominal fat, cognitive decline, and bone loss. Some men have much more of a testosterone decline than others do, but it's not yet clear when a man might benefit from testosterone supplements.
To help answer these questions, Utrecht Medical Center researcher Marielle H. Emmelot-Vonk, MD, and colleagues gave testosterone supplements -- or inactive placebo -- to 237 healthy 60- to 80-year-old men. All of the men had low or low-normal testosterone levels.
"We saw some good results -- men's muscle mass increased and their fat mass decreased -- but this was not accompanied by increased muscle strength, so this was a bit disappointing," Emmelot-Vonk tells WebMD.
The downside was that men who took the oral testosterone supplements had lower HDL cholesterol -- the good kind of cholesterol. This made them slightly more likely to develop metabolic syndrome, a set of metabolic measures that predicts risk for diabetes and heart disease.
Moreover, supplements did not improve cognitive function, increase bone mineral density, or increase overall quality of life over the course of the six-month study.
Oral Testosterone 'Not the Best'
One reason for these "disappointing" results is that oral testosterone supplements may not work as well as supplements such as gels, patches, or injections that provide more stable hormone levels.
"We now think the oral supplement was not the best method of testosterone supplementation to use," Emmelot-Vonk says. "This is because the level of testosterone was hot high enough for the entire 24-hour period. So maybe it would be better to use a form of testosterone that gives better levels for 24 hours, such as patches or injections."
Urologist Robert Davis of the University of Rochester, N.Y. offers testosterone supplements to men with low testosterone who complain of symptoms such as erectile dysfunction or low energy. He notes that oral testosterone supplements are not used in the U.S.
Davis says studies may one day show that testosterone supplements can help men without symptoms. But that remains to be demonstrated, he notes.
The Emmelot-Vonk study appears in the Jan. 2 issue of The Journal of the American Medical Association.