In 2002, Solvay Pharmaceuticals, maker of the testosterone supplement AndroGel, launched a global marketing campaign to pathologize male aging. The gradual and natural decrease in testosterone that all men face was no longer inevitable. Instead, it was a treatable condition called "Low T". The "Testosterone Crisis" was born, and sales skyrocketed.

But while branding can conceal the truth; it cannot change it. The companies behind testosterone supplements like AndroGel, Axiron, and Testim hint that their products can improve mood, boost cognitive function, treat erectile dysfunction, and alleviate depression. The weight of scientific evidence says otherwise.

A new systematic review primarily carried out by researchers at Georgetown University neatly summarizes the available data.

"The prescription of testosterone supplementation for low-T for cardiovascular health, sexual function, physical function, mood, or cognitive function is without support from randomized clinical trials," the reviewers reported in the journal PLoS ONE.

The authors evaluated 156 randomized controlled trials in which testosterone was compared to placebo to treat a variety of conditions. Testosterone did not consistently prevent or treat cardiovascular disease, nor did it consistently improve sexual function or satisfaction, with half of the studies showing positive effects and the other half not showing any effects. It was altogether ineffective at treating erectile dysfunction. The majority of studies showed no effects on psychological well-being or cognitive function.

Testosterone did offer a few benefits. The review indicated a small boost to libido and a robust increase in muscle mass. However, the increase in mass was not accompanied by increases to strength.

As of 2013, roughly 2.2 million American men were taking prescription testosterone. For some, affected by genuine hypogonadism, a condition where the testes do not produce enough testosterone, supplementing the hormone may be called for. But for otherwise healthy men simply undergoing normal aging, testosterone probably won't have much effect. Simpler remedies like exercising and maintaining a healthy weight may provide more of a benefit, the reviewers suggest.

Source: Huo S, Scialli AR, McGarvey S, Hill E, Tügertimur B, Hogenmiller A, et al. (2016) Treatment of Men for “Low Testosterone”: A Systematic Review. PLoS ONE 11(9): e0162480. doi:10.1371/journal.pone.0162480