Why Most “Testosterone Booster” Products Are Built on Studies That Don’t Apply to You

• The majority of ingredient studies cited by testosterone booster brands were conducted on elderly men, hypogonadal men, vitamin-deficient populations, or rats. These results do not transfer to a healthy 35-year-old with normal T.
• Tribulus terrestris is the clearest example: multiple studies showing T increases were in men starting from severely low baselines. In men with normal T, the data is consistently flat.
• D-aspartic acid and fenugreek follow the same pattern – effects concentrated in deficient or clinical populations, near-zero response in replete men.
• Proprietary blends weaponize this ambiguity. You can’t assess a blend when you don’t know the dose of any individual ingredient.
• This doesn’t mean all supplements are useless – it means you need to ask which population the study used before assuming the result applies to you.

Something Joey Savage said in a conversation I’ve thought about since stuck with me. He was talking about how supplement companies approach formulation decisions, and he put it plainly: “There are products in the marketplace that are complete garbage – snake oil – there for whatever flavor of the week ingredient.” He was being diplomatic about it, actually. He didn’t specifically call out testosterone boosters but the logic he was describing applies to no category more directly.

Joey’s background is formulating C4 pre-workout and serving as CSO at Glaxon. He’s been inside the industry since age 22. When he says companies pick ingredients based on marketing feasibility rather than evidence quality, he’s not guessing. He’s describing a business model he watched operate from the inside.

The business model works like this: find a study showing an ingredient raised testosterone. Put that ingredient in a blend. Print the claim. Don’t mention that the study was done on hypogonadal men in their 70s who were severely zinc deficient and started from 150 ng/dL. Your target customer – a 37-year-old with 420 ng/dL who’s been lifting for five years – is not that person. The study does not apply to him. He will buy the product anyway because nobody told him to ask about the study population.

I want to walk through the specific cases because this isn’t abstract.

Tribulus terrestris — the flagship example of misapplied studies

Tribulus was the dominant testosterone supplement ingredient through most of the 2000s. It’s still in a huge number of proprietary blends. The case for it was built primarily on Bulgarian research from the 1980s and 1990s showing meaningful LH and testosterone increases.

What that research used: men with diagnosed hypogonadism, fertility problems, or very low baseline T. Some of the studies were in men with T in the range of 180-250 ng/dL. When a severely hypogonadal man’s LH response is stimulated by a saponin compound, his T can rise – because there’s a significant amount of runway below baseline to recover from. That’s a clinically real effect in a very specific population.

What happened when well-designed trials tested tribulus in healthy men with normal T? The results were consistently flat. Multiple controlled trials in young, healthy males showed no significant change in testosterone, LH, or body composition versus placebo. The ingredient that was sold as a universal T-raiser was, in practice, doing something specifically useful for a population that represents a small minority of supplement buyers.

Sam Reichert – 29, PhD student, analytical mind – told me he’d been taking a tribulus blend for four months before we connected. He’d read about three studies before deciding to buy it, which put him ahead of 90% of the market. The problem was that none of the three studies he’d found mentioned baseline T levels of subjects in the abstract, and he hadn’t gone looking for them. His T was 440 at baseline – well within normal range. The tribulus was doing nothing.

I didn’t run a separate tribulus trial with Sam – we moved him directly to the foundation stack protocol and he responded strongly. But if we’d left the tribulus in and called it a win, I’d have taught him a wrong lesson about what moved his bloodwork.

D-aspartic acid: the mechanism was real, the context wasn’t

(D-aspartic acid, or DAA, is an amino acid that plays a role in the release of luteinizing hormone from the pituitary). The mechanism by which it could raise T is real – it’s upstream in the HPTA pathway. The initial trial that generated the excitement showed a 42% increase in testosterone over 12 days in infertile men.

Infertile men. Not the typical supplement buyer. The study that launched thousands of DAA products used a population with known reproductive dysfunction and almost certainly depressed LH-to-T signaling as part of that dysfunction.

When researchers tested DAA in resistance-trained men with normal testosterone levels, they found no significant T increase, and one well-designed trial in trained athletes found a slight decrease in T after extended use – potentially because pushing LH artificially can create downstream feedback effects.

Jake Brennan sent me a photo of his supplement cabinet when we first started working together. There were two DAA products in it. He’d spent probably $80 on them based on a YouTube video. His T at the time was 380 – low, but not hypogonadal in the clinical sense that made the DAA studies relevant. His actual issue was zinc deficiency and lifestyle. The DAA was doing nothing and he had no way to know that from the marketing.

Fenugreek: the free T story

Fenugreek gets more of a free pass from me than tribulus or DAA because some of the mechanism is cleaner. Certain fenugreek extracts appear to modulate SHBG, potentially increasing free testosterone – and this effect has been demonstrated in some trials in younger, healthy men. So it’s not the same degree of population mismatch.

The problem is that the effect size in healthy men is modest – generally not large enough to justify the price premium of branded fenugreek extracts in most proprietary blends. And it gets lumped in with tribulus and DAA in the marketing materials as if they’re all in the same evidence category. They’re not, but the presentation treats them as equivalent.

More importantly: if SHBG is what you’re trying to address, boron does it more cleanly with a cleaner evidence base and costs roughly one-fifth the price. The boron article covers that specific use case in detail. I mention fenugreek not to condemn it entirely but to put it in appropriate context relative to cheaper alternatives that work through similar mechanisms.

The proprietary blend problem

Proprietary blends are the vehicle through which most of these misapplied ingredients reach consumers. The blend structure is elegant from a marketing standpoint: you list ten ingredients, provide a total blend weight, and never disclose individual ingredient doses. The consumer can see that the product contains the ingredients they’ve heard about. They cannot assess whether any of them are at a therapeutically relevant dose.

Joey’s point on this was direct: “Most of the proprietary blended ingredients are worthless” because the cost-per-ingredient in a blend is extremely high for the consumer, and companies typically use sub-effective doses of the more expensive ingredients while front-loading with cheaper fillers. You’re often buying the label, not the dose.

The solution is simple in principle: buy ingredients individually at known doses. This is the approach I outline in the foundation stack article. Zinc picolinate at 25-30mg. Vitamin D3 + K2 at specific doses. Magnesium glycinate at a known elemental magnesium content. You know exactly what you’re getting and at what dose. You can’t know that with a proprietary blend.

Why “it worked for me” doesn’t tell you what you think it tells you

This is the counterargument I hear most often, and I want to address it directly. Someone tries a testosterone booster blend that contains tribulus, DAA, fenugreek, zinc, B6, and magnesium – and their T goes up. They conclude the product worked.

Maybe it did. But which ingredient moved the bloodwork? If they were zinc deficient – which is common – the zinc in the blend fixed the deficiency, and that’s what moved the number. The tribulus and DAA contributed nothing. The marketing gets credit for a result that a $12 bottle of zinc picolinate would have produced alone.

This is exactly why I push clients toward testing first and single-variable interventions when possible. Not because I’m obsessively scientific about it, but because the feedback loop of “I took a blend and my T went up” teaches nothing actionable. You can’t replicate it, optimize it, or apply the lesson to future decisions if you don’t know which variable mattered.

Sam eventually ran exactly this kind of self-experiment. After his foundation stack had been running for three months, he wanted to understand his response better. We added zinc first (his D3 and magnesium were already in range), retested. Then D3, already adjusted. He ended up writing me a five-page analysis of his own bloodwork responses that I still have filed somewhere. The point is: the methodology mattered to him because he was a researcher by training. Most men don’t need to go that deep. But they do need to understand that “I took a blend and my T went up” is a different claim from “I identified the specific intervention that moved my bloodwork.”

What the evidence actually does support

I’m not making the case that all supplementation is noise. I’ve built a full supplement tier system through the supplement tier list that distinguishes between what genuinely moves bloodwork and what’s marketing. The S-tier – zinc when deficient, D3 when deficient, magnesium glycinate, boron for SHBG – works because the mechanisms are well understood and the populations studied include healthy adult men.

Ashwagandha KSM-66 has legitimate cortisol and T data in younger healthy men with normal T ranges. Tongkat ali has reasonable evidence in healthy populations, particularly in men on the lower end of normal or experiencing exercise-induced stress. These are in the A-tier category because the evidence holds up better to scrutiny of the study populations.

The question to ask about any supplement ingredient before you buy it is not “does it raise testosterone” – it’s “does it raise testosterone in someone with a profile similar to mine, starting from a similar baseline?” That question filters out most of what’s sold as a testosterone booster. The ones that survive the filter are worth understanding. The ones that don’t – and tribulus, DAA, and most proprietary blends fall in this category for the majority of buyers – aren’t worth spending money on until you’ve maxed out the options that actually work.

The industry’s financial structure pushes against you knowing this. That’s not paranoia, it’s just how margins work. The ingredients with the best evidence for healthy men are mostly inexpensive commodities. The ingredients with the most marketing dollars behind them are mostly the ones where the evidence base is narrower than the claims suggest.

Ask about the study population. That one question will save you a significant amount of money over a lifetime of supplementation.