If the adverts are to be believed, testosterone supplements are a cure-all for men facing the unfortunate effects of middle age. The hormone is claimed to improve muscle strength, energy and sex drive. However, not only is there little evidence for this, several studies have found a link with heart disease.
Traditionally, testosterone was prescribed to men with abnormally low levels due to a congenital condition or damage to the testes from chemotherapy. Now, though, middle-aged men are being prescribed “testosterone replacement therapy” (TRT) to make up for the natural decline that often comes with age.
In the US, the number of men being prescribed testosterone rose from 1.3 million to 2.3 million in the five years up to 2013, and the UK has seen a similar trend, although the numbers are far lower (see graph).
But in March, the US Food and Drug Administration cautioned that testosterone should only be prescribed to men with low levels caused by medical conditions, rather than general ageing, and confirmed by a lab test. The European Medicines Agency has issued a similar statement.
The health bodies also asked manufacturers and prescribers of testosterone products to warn users about a possible risk of heart attacks and strokes after a number of studies showed an association. One trial was even terminated early due to an “excess of cardiovascular events” among participants. Worryingly, a 2013 analysis found that the level of cardiovascular risk reported varied, depending on whether the study was funded by the pharmaceutical industry.
One possible mechanism for testosterone’s effect on …
