Walk into any supplement shop and you’ll find a shelf of products promising to raise your testosterone. The packaging is confident. The evidence, for the most part, is not.

This isn’t a case of a few bad products among good ones. The category as a whole has a problem.

What’s usually in them

Most testosterone boosters are built from the same short list: tribulus terrestris, D-aspartic acid, fenugreek, zinc, magnesium, vitamin D, ashwagandha, and some combination of B vitamins. Formulations vary, doses vary enormously, and proprietary blends often hide how much of anything you’re getting.

What the trials show

Tribulus terrestris appears in a large proportion of these products and has been studied reasonably well. Controlled trials in men have generally failed to show a meaningful rise in testosterone. Its reputation appears to rest on early animal work and marketing momentum rather than human data.

D-aspartic acid showed promise in a small early study, which is largely why it’s everywhere. Larger and better-controlled follow-ups have been disappointing, with at least one finding levels fell at higher doses in resistance-trained men.

Fenugreek has a handful of small trials with mixed results. Some report modest changes, often in sexual function scores rather than measured testosterone, and several were industry-funded. Not nothing, but a long way from established.

Zinc, magnesium and vitamin D are the genuine exceptions, with an important caveat covered below.

The deficiency caveat

Correcting a real deficiency in zinc or vitamin D can improve testosterone. Topping up someone who already has enough does nothing measurable.

This single distinction explains most of the confusion in the field. A trial in deficient men shows a benefit; a trial in healthy men shows nothing; both get cited by whoever they suit. If you want to know whether this applies to you, test rather than guess — it’s a cheap thing to measure.

Why the category survives

Several reasons, none of them about efficacy.

Supplements are regulated far more lightly than medicines. In Australia they are typically listed rather than registered with the TGA, which means they’re assessed for ingredient safety but not for whether they do what the label implies.

Testosterone also varies naturally, and most men start taking something when they feel at their worst. Regression to the mean does a lot of unearned work. Add the placebo effect — genuinely strong for subjective things like energy, mood and libido — and a product can feel effective without doing anything.

The genuinely risky end

Some products marketed as natural boosters, particularly those bought online from overseas, have been found to contain undeclared anabolic steroids or SARMs. Being sold as a supplement is not evidence of being one.

If a product produces dramatic results, that is a reason for suspicion rather than reassurance. Unlabelled androgens suppress your own production and carry real cardiovascular and liver risk, and you have no idea of the dose.

What to do instead

If you have symptoms that have persisted for months, the useful step is finding out what your levels actually are and what’s driving them. That’s a blood test and a conversation with a doctor, not a tub.

If your bloods come back normal, a supplement was never going to be the answer and something else is causing your symptoms — worth knowing. If they come back low, you have a medical issue, and the treatment for that is also not a tub.

This article is general information, not medical advice. Speak to a doctor or pharmacist before starting any supplement, particularly if you take other medicines.