Testing and evidence

What An Assay Finds Inside A Nootropic Bottle

Every so often a laboratory buys a shelf of supplements, opens them and measures what is inside. The published results are the closest thing this category has to an audit, and they are worth reading before deciding how much any front-of-pack badge is worth.

By Primal Grow Pro Team · Last updated October 29, 2026 · 10 min read · Testing and evidence · Reviewed by Dr. Jonathan Clavell, MD

What an assay actually is

An assay measures how much of a specified compound is present in a sample. In supplement research the design is simple: buy products off the open market, extract the capsule contents, measure against a reference standard, compare with the label.

That last step is what turns a measurement into a finding. A laboratory reporting “this capsule contains 40 micrograms of huperzine A” has produced a number. A laboratory reporting “this capsule declares 200 micrograms and contains 40” has produced a finding, and the difference between the two is the label.

A second kind of assay works differently. Screening for compounds that should not be present at all needs no declared figure, because the finding is the presence rather than the discrepancy. Both kinds appear below.

Twenty-two bottles of huperzine A

A 2020 study published in Clinical Toxicology examined 22 US brain-health dietary supplement products carrying huperzine A, a club moss alkaloid used in cognitive formulas and dosed in micrograms rather than milligrams.

The measured servings ran from below the limit of quantification to 267 micrograms. Only two of the twenty-two came within 10 per cent of the amount printed on their own labels.

Two things make that heavier than it looks. Huperzine A is pharmacologically active at these amounts, and it is dosed in micrograms, so a tolerance that would be trivial on a 500 mg ingredient is proportionally enormous here.

The finding is about the category rather than about any single company. What it establishes is that a printed number on a cognitive supplement label is a claim rather than a measurement, and that the claim is frequently wrong in both directions.

Five published studies. The first three needed a declared figure to produce a finding. The last two did not, because the presence of a prescription drug is a finding on its own.

Twenty-three bottles of vinpocetine

An earlier study in Drug Testing and Analysis identified and quantified vinpocetine in 23 US dietary supplements that carried it.

Servings ran from 0.3 mg to 32 mg, which is a hundredfold spread across products sold for the same purpose at comparable prices. Six of the twenty-three contained no measurable vinpocetine at all.

A hundredfold spread means two buyers taking what they believed was the same ingredient could be taking wildly different amounts, with no way of knowing.

Vinpocetine is also worth understanding for a second reason. It is not a plant extract: it is a semi-synthetic derivative of vincamine, made in a laboratory from a plant-derived starting material. Products describing it as a natural botanical extract are describing it inaccurately, which is a labelling problem of a different kind.

When the finding is a drug rather than a shortfall

A 2021 analysis in Neurology Clinical Practice went looking for something else in cognitive-enhancement supplements: compounds that have no business being in a dietary supplement at all. It identified five unapproved drugs across the products it examined.

This is the second kind of assay and it needs no declared figure to produce a result. A prescription-only or unapproved compound found in a capsule sold as a dietary supplement is a finding whatever the label says, because the label cannot have declared it.

The practical danger is specific and it is not about the amount. Somebody knowingly taking a pharmacologically active compound can be warned about interactions and contraindications. Somebody who believes they are taking a herbal blend cannot be warned about anything, because neither they nor whoever manages their health knows what is in the bottle.

The sexual-enhancement problem

The male vitality shelf has its own version of the same finding and it is the most serious one in this whole post.

A screening study of sexual-enhancement supplements looked for synthetic PDE5 inhibitors in products marketed as natural and found them. A 2025 quantification study detected and measured sildenafil and tadalafil in supplements sold as natural sexual enhancers.

These are not isolated results: regulators publish warning lists about adulterated sexual enhancement products continuously.

The danger is precise rather than general. Sildenafil interacts dangerously with nitrates, prescribed for angina, and the combination can drop blood pressure severely. A man taking what he believes is a herbal capsule has no reason to think about it.

The systematic evidence review of male supplement ingredients provides the wider context: a category whose finished products have no published randomised evidence behind them, and whose most dramatic results have sometimes had a pharmaceutical explanation.

Why a declared figure is what makes an assay possible

Reading the five studies together, one structural point emerges that is easy to miss.

The first three depended entirely on the products declaring an amount. The finding in each case was a discrepancy, and a discrepancy requires two numbers: the one on the label and the one in the capsule. Remove the label figure and the laboratory can still measure, but it cannot report that anything is wrong.

The last two did not depend on a declaration, because the presence of an undeclared prescription drug is a finding regardless. That is the one form of accountability that survives a missing panel, and it only catches the most serious kind of problem.

So a printed panel is not merely useful to a buyer comparing products. It is the precondition for the whole external-checking apparatus that exists around this category. A panel is what makes a company checkable.

What happens when nothing is declared

Which brings the argument to the uncomfortable place it has to reach.

A product publishing no amount for any ingredient cannot fail a label-comparison assay. It also cannot pass one. It sits outside that form of accountability entirely, and no laboratory in the world can put it back inside without a figure to measure against.

That is not an accusation. A capsule with no published amounts may contain exactly what its maker intends, at sensible levels, made carefully. The point is narrower and harder to argue with: nobody outside the company can establish it, and no published study can produce a finding about it either way.

The product sold on this website is in that position. Seven names, no figures, and no independent analysis published by anybody. The batch page sets out what the lot reference does and does not establish, and it is careful to say that a filing reference is not a laboratory result.

What a real certificate of analysis carries

Seven fields. A GMP badge and an FDA-registered-facility badge on a front panel establish none of them.

Seven fields, and the gap between that document and a badge on a front panel is the whole of the difference between verification and reassurance.

A GMP badge says a facility claims to work to good manufacturing practice. An FDA-registered-facility badge says a factory appears on a list. Neither is a measurement of anything in the bottle in your hand, and neither names the organisation that would stand behind such a measurement. The testing and quality page reads all ten badges on this pack out loud, one at a time.

What a buyer can actually do

• Prefer products that declare amounts. Not because a declaration guarantees accuracy, but because it is the precondition for anybody ever checking.
• Ask whether any lot has been independently assayed, and whether the report can be read. The answer is informative whatever it is.
• Be sceptical of dramatic, immediate effects. Botanicals do not behave that way, and the published explanations for products that do are not reassuring ones.
• Buy from a seller with an address, a telephone number and a written refund procedure. Where nothing can be verified in advance, the ability to undo the purchase is the practical substitute.
• Tell whoever manages your health what you are taking. This is the step that protects against the adulteration problem, because it puts a name on what is in the cupboard.
• Read the ingredient names even without amounts. Knowing that a formula contains St. John’s wort matters at any quantity.

None of that turns a buyer into a laboratory, and nothing available at a kitchen table will. What it does is put the decision on the right footing: this is a category where external verification is thin, the published audits that exist are unflattering, and the sensible response is to prefer companies that make themselves checkable and to keep the receipt.

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