A large-scale, long-term double-blind study found that low testosterone levels were far, far lower than previously suspected, and showed that taking testosterone supplements didn't confer most of its reputed benefits — no memory improvement and no physical vitality.
Testosterone does improve libido, though not as much as Viagra does, and does help with anemia and low bone-density. It also increases the risk of heart attacks in some men.
All told, the studies found that T did not improve men's physical function or vitality. Nor did it help with age-related memory impairment. It did help with anemia and bone mineral density. It increased sexual desire and activity, but the effect was modest; men were better off using Cialis or Viagra. The most worrisome findings came from a study on cardiovascular risk: In men with certain risk factors, T accelerated coronary atherosclerosis, possibly increasing their chance of heart attack.
Assessing the studies in JAMA, endocrinologist David J. Handelsman underlined how little evidence there was to support popular claims of T's powers. And yet, he observed, "rejuvenation fantasies thrive on hope without needing facts."
The Testosterone Myth [Katrina Karkazis/Wired]