DHEADehydroepiandrosterone

DHEA, dehydroepiandrosterone, is a steroid hormone produced mainly by the adrenal glands. It functions largely as a precursor, converted in peripheral tissues into testosterone and oestrogen, and it circulates mostly as its sulphate form, DHEA-S, which is what laboratories measure.

Its levels peak in the twenties and decline steadily with age, falling to a fraction of peak by the seventies. That decline, combined with its position upstream of the sex hormones, made it an obvious candidate for anti-ageing supplementation.

The trial evidence has been consistently underwhelming. Studies in older adults have found small or no effects on body composition, strength, cognition, mood and quality of life, and where effects appear they are modest and inconsistent. It has not delivered on the premise.

There is a genuine clinical use in adrenal insufficiency, where DHEA replacement is sometimes prescribed, and it is a legitimate diagnostic marker: a markedly raised DHEA-S points towards an adrenal source of excess androgens, which matters in investigating conditions such as PCOS.

Its regulatory status differs sharply by country. In the UK it is a prescription only medicine and not legally sold as a supplement; in the United States it is available over the counter, which is why it appears in online anti-ageing marketing aimed at both.

As a precursor to testosterone and oestrogen, it is also prohibited in sport, and it carries the side effect profile that implies, including acne, hair changes and hormonal disruption.

In practice, this is a prescription hormone rather than a supplement, and an abnormal DHEA-S result belongs with an endocrinologist.