Independent supplement ratingsUS and Canada · Updated weekly
A ratings desk for a category that has spent thirty years grading its own homework.
A ratings desk for a category that has spent thirty years grading its own homework.
Researchers put 50 of these products through the literature. Three in five ingredients had no published data at all. Two survive the check, with conditions.
The short answer: almost none of them, and the category has been audited. When researchers took fifty testosterone boosters off the shelf and looked for published evidence behind their ingredients, 61.5% had no data at all on whether they affect testosterone — and one in ten contained something with evidence it pushes testosterone down. Two ingredients survive the check. Both work best in men who were low to begin with.
In 2020, a team at the University of Southern California published exactly the audit this category deserved. They pulled fifty "T booster" supplements, catalogued every active ingredient, then searched PubMed for anything supporting the claims on the label. (Clemesha, Thaker & Samplaski, 2020)
What they found:
Read the last three lines together. For most of what you are buying, nobody has ever tested whether it does the thing on the front of the bottle — and you are more likely to be holding an ingredient with evidence against it than one that has simply been studied and found neutral.
The same paper found the median product carried 1,291% of the recommended daily intake of vitamin B12, 807.6% for B6 and 272% for zinc. Eight ingredients per bottle, most of them unstudied, several of them at doses chosen to look serious on a label rather than to do anything.
DAA is the reason testosterone boosters became a category. An early trial in untrained men reported a rise in testosterone, the industry moved in, and it is still on labels today — including one product in our ranking.
Then it was tested properly in the population that buys it. A 2017 randomised, double-blind, placebo-controlled trial gave resistance-trained men 6 g of DAA a day for twelve weeks alongside a supervised four-day-a-week training programme. Total testosterone: no change. Free testosterone: no change. Strength and muscle growth: the same as placebo. Estradiol dropped 16%. (Melville, Siegler & Marshall, 2017)
The authors' conclusion is one sentence: DAA supplementation is ineffective at changing testosterone levels or positively affecting training outcomes. An earlier trial at 3 and 6 g in the same population found the same thing. (Melville et al., 2015)
It is still sold. Our ingredient page keeps the full record.
Tribulus has been marketed as a testosterone booster since the 1990s. A 2021 randomised placebo-controlled trial gave thirty trained men 770 mg a day for six weeks and measured body composition, hormones and performance across five benchmark workouts. It did not improve performance or body composition. (Fernández-Lázaro et al., 2021)
The authors note a signal on testosterone and on bench press, and are careful about it — a single measure moving in a six-week trial of thirty people is a reason to run a bigger study, not a reason to buy anything.
Eurycoma longifolia is the exception that makes the category interesting. A 2022 systematic review and meta-analysis pooled five randomised trials and found a significant increase in total testosterone (SMD 1.352, 95% CI 0.565–2.138, p = 0.001), holding up in the subgroup of men who were hypogonadal to start with. (Leisegang et al., 2022)
Read the last clause carefully, because the industry does not. The effect is clearest in men whose testosterone was low. The authors say plainly that more research is needed before clinical use. That is a real finding and a modest one, and it is a long way from what a bottle promises a healthy 25-year-old. More on our tongkat ali page.
The best-designed testosterone trial on ashwagandha ran sixteen weeks, double-blind, placebo-controlled and crossover, in overweight men aged 40 to 70 reporting mild fatigue. Eight weeks of a standardized extract produced a 14.7% greater increase in testosterone than placebo (p = .010) and an 18% greater increase in DHEA-S. (Lopresti, Drummond & Smith, 2019)
And here is the part that never makes the label: there were no statistically significant differences between the groups in fatigue, vigor, or sexual well-being. The hormone moved. How the men felt did not.
That is a useful, honest result about a real ingredient, and it is also the reason we rate ashwagandha as a stress supplement rather than a testosterone one.
Testofen, the standardised fenugreek extract that appears on several labels in this category, has a 2016 double-blind randomised trial in healthy ageing males reporting increased testosterone and improved sexual function. (Rao et al., 2016)
One trial on a branded extract, in ageing men, is a starting point rather than a body of evidence. When you see Testofen on a label, check the dose against the studied one — several products list the name and a fraction of the amount. The Label Dose Checker does that comparison for you.
Suppose a product does raise your testosterone. Does that build muscle?
Not necessarily, and the pattern in the trials above explains why. The effects that show up appear in men who were hypogonadal, ageing, overweight or fatigued — men with room to move. In healthy young men with normal testosterone, a supplement nudging a number that is already in range has not been shown to add muscle or strength. The DAA trial is the cleanest demonstration: twelve weeks, supervised training, and the supplement group gained exactly what the placebo group gained.
Which reframes the whole shelf. These products are sold to men who train, and the evidence that exists comes from men who mostly do not.
Nothing you can buy in a bottle competes with the boring answers, and they are worth stating because they are free:
The category is mostly unstudied ingredients sold at doses chosen for the label. Two ingredients — tongkat ali and ashwagandha — have real randomised evidence, both modest, both strongest in men who were low or stressed to begin with. One ingredient that built the category has been tested in the people who buy it and failed.
If you still want one, the questions worth asking are on our method page: is every dose disclosed, is each active at the amount used in the research, and what does a serving cost. Our ranking of six testosterone boosters answers all three for each product, and five of the six cannot even be priced per gram of active ingredient because the doses sit inside a blend.
Educational only, not medical advice. Low testosterone is a clinical diagnosis made with a blood test, not something to treat from a supplement shelf. If you suspect it, see a doctor.