Do Testosterone Boosters Work? Not One Product Has Ever Been Tested
A systematic review published in 2024 went looking at two decades of data on 27 different testosterone boosters across 52 studies. Its finding, in seven words: “most fail to increase total testosterone.” [1]
But the more damning number is not about whether they work. It is about whether anyone has checked.
Not one product on the shelf has been tested
In 2021, researchers took the top 16 testosterone supplements and top 16 erectile dysfunction supplements sold on Amazon, Walmart, Vitamin Shoppe and A1 Supplements. They pulled out all 37 ingredients and went looking for randomised controlled trials. They found 105 of them. [2]
And then they wrote this: “No whole supplement products have published RCT evidence.” [2]
Read that carefully, because it is the whole page. Some of the ingredients have been studied. Not one of the products has. The thing you would actually swallow — that specific combination, at those doses, in that proportion — has never been put in a trial against a placebo by anybody.
It gets thinner. Of the 37 ingredients, only 19% earned the top grade for evidence, meaning net positive results in two or more randomised trials. 68% landed in the bottom two grades — contradicting, negative, or simply absent evidence. And about a third of the ingredients in testosterone supplements had no published randomised trial evidence at all. [2]
The evidence that does exist is mostly not in humans
A year earlier, a different team took the five highest-rated testosterone boosters on Amazon — average rating 4.56 stars, thousands of reviews each — and reviewed the literature behind their ten commonest ingredients. [3]
They found 191 studies. Of those, 19% involved human subjects. Fifty-three per cent were animal models, 15% were done in a dish, and 12% were case reports or review articles.
So what did the human studies find? Among those 37 studies: 30% saw testosterone rise, 3% saw it fall, 46% found no effect, and 22% were indeterminate. [3]
Roughly one human study in three found the thing the entire category is named after.
So where do the five-star reviews come from?
This is the part of that study that deserves to be much better known.
The researchers took the customer reviews for those five products and scored them against the themes of a standard clinical questionnaire for androgen deficiency — libido, energy, strength, erections, mood, sleep, work performance. Then they ran the same reviews through ReviewMeta, a tool that flags untrustworthy Amazon reviews, and scored them again.
| Reported better strength or endurance | −93% |
| Reported increased libido | −91% |
| Reported improved mood | −89% |
| Reported better sleep | −67% |
| Reported better erections | −60% |
| Reported more energy | −59% |
| Reported better work performance | eliminated |
Ninety-one per cent of the reports of increased libido did not survive the filter. Ninety-three per cent of the strength reports. Every single report of improved work performance disappeared. [3]
That is not a statement about whether the supplements work. It is a statement about what you are reading when you read the reviews — and the reviews, not the evidence, are what sells a 4.56-star product.
Ingredient by ingredient
Tribulus terrestris is the single most common ingredient in these products. [2] In a placebo-controlled trial, 21 young men took 10 or 20 mg per kilogram of bodyweight daily for four weeks, with hormones sampled repeatedly out to 24 days. Testosterone came out at 454 and 471 ng/dL in the supplemented groups versus 512 in placebo — no significant difference, and if anything numerically lower. Androstenedione and luteinising hormone did not move either. The paper’s title says it: Tribulus “does not influence the androgen production in young men.” [4]
D-aspartic acid got a proper test in 2017: 22 resistance-trained men, 6 grams a day, twelve weeks, randomised, double-blind, placebo-controlled, on a supervised training programme. “No change in basal TT or FT were observed.” Both groups gained strength and muscle equally. The authors’ verdict: “DAA supplementation is ineffective at changing testosterone levels, or positively affecting training outcomes.” [5] It did lower oestradiol by 16%, which nobody was asking for.
Zinc is the interesting one, and the two best sources disagree. A 2023 systematic review concluded that zinc deficiency lowers testosterone and zinc supplementation raises it — but 30 of its 38 papers were animal studies, only eight were clinical, and it noted the effect “may vary depending on basal zinc and testosterone levels.” [6] The 2024 review of human trials put zinc among the things that fail. [1]
The reading that fits both: if you are genuinely zinc deficient, correcting that appears to help. If you are not, there is no good human evidence that more does anything. Which is the same shape as most micronutrient stories, and not what the label implies.
Fenugreek has a meta-analysis reporting a significant effect on total testosterone. [7] It pooled four trials. Four. That is worth knowing about and it is not worth much yet.
Vitamin D does nothing, and this has been measured carefully — a randomised trial using mass spectrometry found no effect, and a meta-analysis of eight trials agreed. We covered it properly in part four.
What did show something
We are not going to leave you with the impression that nothing on earth moves testosterone, because that would be its own kind of dishonesty.
The 2024 review named its exceptions, and the wording matters. Beta-hydroxy beta-methylbutyrate and betaine “can be considered effective for male athletes”. Eurycoma longifolia and two trademarked preparations — a pomegranate-rind and cocoa-seed blend, and a purified shilajit extract — are “possibly effective” for men with late-onset hypogonadism. Eurycoma longifolia and Withania somnifera are “possibly effective” for healthy men. [1]
Note what those sentences are doing. Not “effective” — possibly effective, in a named population. Three studies apiece, in the case of the last two.
Withania somnifera is ashwagandha, and we have a whole verdict on it. Pooled across 23 trials it raised testosterone in men by 57 ng/dL — a real, measurable change, in a page we rated Preliminary rather than Supported, for reasons that page sets out at length. That is roughly what the weight-loss evidence delivers, except the weight-loss evidence runs to 44 studies and 1,774 men.
The verdict
Testosterone boosters, as a category, are Unsupported. The systematic review that asked the question directly found that most fail. Roughly half of the human studies on the commonest ingredients found no effect. And no product sold as a testosterone booster has ever been tested as sold.
A handful of individual ingredients have shown something in a handful of trials, mostly in specific populations, with the reviewers themselves reaching for the word possibly. None of that supports the claim on the bottle, which is not “this ingredient possibly does something in men with late-onset hypogonadism”.
If your number is genuinely low and you have symptoms, the conversation is with a doctor. If you are carrying extra weight, the intervention with the best evidence is free and does about as much as the best-performing supplement in this whole field. And if you are about to buy something because it has four and a half stars, it is worth remembering what happened to those stars when somebody checked them.
Part 5 of a series on testosterone. Earlier: whether to get tested, what normal means, free versus total, and what actually raises it.
Related: how to increase testosterone naturally · ashwagandha benefits · free vs total testosterone · is creatine safe
