Common myths and misunderstandings

The central claim is that these supplements will raise testosterone levels, but the evidence is weak. For example, a systematic review published in the International Journal of Impotence Research found that while 69 per cent of ingredients in popular testosterone supplements had some published trial evidence, no whole supplement product had been tested in a robust randomised controlled trial.

Critically, 68 per cent of individual ingredients received a grade of C or D, meaning evidence was contradictory, negative or simply absent.

Many consumers also assume that natural means safe, but natural origin does not guarantee safety, and several ingredients in testosterone boosters carry real risks.

For example, DHEA is a steroid hormone precursor and supplementing it can raise both testosterone and oestrogen levels unpredictably. 

Potential side effects include acne, mood changes and, at higher doses or with longer use, concerns about hormone-sensitive conditions, effects on HDL cholesterol, and interactions with antidepressants, cancer medicines and drugs that affect oestrogen levels.

DHEA is also a banned substance under World Anti Doping Agency (WADA) rules, which matters for any customer who competes in sport.

Some products marketed as natural testosterone boosters have been found to contain undeclared SARM (selective androgen receptor modulator) compounds like ostarine or RAD-140.

These are not licensed medicines but have appeared as hidden ingredients in supplements, and have been linked to serious liver injuries.