What a proprietary blend actually hides

Most reports in this beat go looking for the study behind a claim. This one is about the step before that, because there is a common situation where finding the study does not help you at all.

Say the trial is good. Say it really did use 600 mg of the extract, in people, against placebo, and found something. You go to buy the thing, and the panel on the back reads:

Proprietary Blend 750 mg *
Ingredient A, Ingredient B, Ingredient C, Ingredient D, Ingredient E, Ingredient F, Ingredient G, Ingredient H, Ingredient I
* Daily Value not established

One number for nine ingredients. The question of whether you are getting the studied dose is not answerable from that label, and it is not answerable because federal law says it does not have to be. I want to show you exactly where that permission is written, what it does not cover, and what you can still work out.

The default rule, which is stricter than people think

Start with what a supplement label normally owes you. The Supplement Facts panel is governed by 21 CFR 101.36, and the section covering ingredients that have no established Daily Value, the botanicals and extracts and mushroom powders that make up most of the interesting shelf, is paragraph (b)(3). Its requirement is specific:

The quantitative amount by weight per serving of other dietary ingredients shall be presented in the same manner as the corresponding information required in paragraph (b)(2)(ii) of this section...

Each one, by weight, per serving. And the regulation goes further, closing a loophole most people have never considered: "The quantitative amount by weight shall be the weight of the other dietary ingredient listed and not the weight of any component, or the source, of that dietary ingredient." You cannot list 500 mg of an extract and mean 500 mg of the mushroom it came from.

So the baseline is an itemized panel. Proprietary blends are the exception to that baseline, not the norm it was built around.

Seven words in a statute

The exception does not originate in an FDA regulation. It is in the law itself, put there by the Dietary Supplement Health and Education Act of 1994, and it is remarkably short. Here is 21 U.S.C. § 343(q)(5)(F)(ii), complete:

the listing of dietary ingredients shall include the quantity of each such ingredient (or of a proprietary blend of such ingredients) per serving;

That parenthetical is the entire thing. Seven words, inside brackets, in the middle of a sentence that otherwise requires exactly what you would want. Congress wrote a disclosure requirement and then wrote an alternative into it, and every proprietary blend on every shelf in America stands on those seven words.

The regulation implementing it is 21 CFR 101.36(c), and it is worth reading because it is more demanding than its reputation. The blend gets identified as such: "A proprietary blend of dietary ingredients shall be included in the list of dietary ingredients described in paragraph (b)(3)(i) of this section and identified by the term 'Proprietary Blend' or other appropriately descriptive term or fanciful name." The ingredients must be named and, crucially, ordered: they "shall be declared in descending order of predominance by weight, in a column or linear fashion, and indented under the term 'Proprietary Blend'." And the number shown "shall be the total weight of all other dietary ingredients contained in the proprietary blend."

Every ingredient is named. Nothing hides its identity. What disappears is one thing only, and it happens to be the thing that decides whether a product does anything: how much.

What a blend cannot hide

This is where the popular version of the story goes wrong, and I would rather be accurate than on-side.

You cannot bury a vitamin or mineral in a blend. Paragraph (c)(1) sends anything with an established Reference Daily Intake or Daily Reference Value straight back to the itemized rules: "Dietary ingredients contained in the proprietary blend that are listed under paragraph (b)(2) of this section shall be declared in accordance with paragraph (b)(2) of this section." If there is vitamin D or calcium or iron or potassium in there, it gets its own line and its own number, blend or no blend.

The identity of every ingredient is disclosed, as noted. And FDA is not in the dark either. The industry's trade association, the Council for Responsible Nutrition, makes this point in its own defense of the provision, and it is a fair one: "FDA can obtain the exact ingredient mixture in proprietary blends when it conducts routine inspections of facilities under the GMP regulations."

So the accurate statement is narrow. A proprietary blend conceals the per-ingredient amounts of the non-vitamin, non-mineral ingredients, from you, on the label. It does not conceal what is in the product, and it does not conceal the amounts from the regulator.

The case for it, stated fairly

I am a formulator. I should tell you that the business reason here is real, not invented as cover.

The ratios in a formula are frequently the only thing separating one product from a cheaper copy of it. CRN's position paper puts it directly: the quantities and ratios "are considered a trade secret, like a special recipe," and disclosing exact formulas "would allow competitors, store brands and even counterfeiters to make exact copies." Their comparison is to Coca-Cola. It is not a ridiculous comparison. Developing a formula costs money, and there is no patent protection waiting at the end of it for most botanical combinations.

The problem is not that the rationale is fake. It is that the rationale and the harm are both true at once, and the cost falls entirely on the person who cannot verify what they bought. A trade secret is a legitimate thing to protect. It is also, from where you are standing at the shelf, indistinguishable from a formula built to look impressive and cost nothing.

That second pattern has a name in the trade: fairy dusting. You put a genuinely expensive, well-studied ingredient in the blend at a token amount, list it prominently, and let the total weight come from something cheap. Every claim you make about that ingredient is technically about an ingredient that is present. The blend format is what makes it invisible.

The arithmetic the ordering rule gives you

Here is the part I do not see written down often, and it comes straight out of the regulation's own requirements.

The rule says descending order of predominance by weight. The rule also says the printed number is the total weight of everything in the blend. Those two facts together are enough to derive a hard upper bound on any individual ingredient, and you can do it standing in the aisle.

If the ingredients are in descending order, then every ingredient listed above position k weighs at least as much as the one at position k. So the first k ingredients together weigh at least k times the weight of ingredient k. And they cannot weigh more than the whole blend. Therefore:

ingredient at position k ≤ total blend weight ÷ k

Take the label at the top of this report. Nine ingredients, 750 mg total. Suppose the one you actually care about, the one from the trial, is listed fifth. It weighs at most 750 ÷ 5, which is 150 mg. The trial used 600 mg. You have just falsified the dose claim without a laboratory, a phone call, or a single piece of information the company chose to give you.

If it is listed last, ninth of nine, the ceiling is 750 ÷ 9, or about 83 mg. If it is listed first, all you know is that it is at least 750 ÷ 9, which is the same 83 mg, and it could be almost the entire blend.

Be clear about the limits of this, because a tool oversold is worse than no tool. It gives you a ceiling, never an actual amount. It tells you nothing useful about the first ingredient. And a ceiling of 150 mg is entirely consistent with 2 mg. It answers exactly one question: is the studied dose even arithmetically possible here? Quite often the answer is no, and no is a complete answer.

One more thing worth knowing about the total itself. Compliance for these panels runs through 21 CFR 101.36(f)(1), which notes that "Reasonable excesses over labeled amounts are acceptable within current good manufacturing practice." The declared blend weight is a floor of sorts rather than a precise statement, which is normal manufacturing practice and not a scandal, but it means the arithmetic above should be treated as a rough bound rather than a measurement.

Why the military got there first

The Department of Defense runs a program called Operation Supplement Safety, because service members are subject to drug testing and to physical demands that make an undisclosed stimulant a genuine problem rather than an abstract one. Their page on blends states the rule in one sentence: "The specific amount of each individual ingredient in a proprietary blend does not have to be listed; only the total combined amount in the blend must be given."

And their conclusion is the one I would give: "The only way to know what is in any particular dietary supplement product is through laboratory testing, which is why it's important to look for third-party certification."

That is the honest end state. The label tells you what is present. Independent testing is what tells you how much. I went through what happens when somebody actually runs that testing in an earlier report, and the results are not reassuring.

What I would actually do at the shelf

Find the ingredient you came for, and count. Its position in the list, divided into the blend total, is your ceiling. Do that before anything else.

Compare the ceiling to the study. If a product is sold on the strength of research, the research used a dose. If the ceiling is below it, the story is over and you did not need anyone's permission to end it.

Treat a long list as a warning rather than a feature. Twenty ingredients in a 500 mg blend means the average is 25 mg and most of them are below that. A long ingredient list inside a small blend is arithmetic telling you something.

Notice what is not in the blend. Vitamins and minerals are itemized by law. If a product shows real numbers for those and hides everything else, the disclosure you are seeing was not a choice.

Prefer a fully disclosed panel when one exists, and understand that you are asking a company to give up a legal protection it is entitled to keep. Plenty do it anyway, and it is reasonable to reward that.

The signal

A dose is not a detail attached to an ingredient. It is most of what an ingredient is. Nearly every honest sentence anyone can say about a supplement is a sentence about a quantity, which is why "clinically proven" collapses so reliably: the study proved something about 600 mg, and the bottle is not obligated to tell you whether it contains 600 mg or six.

The proprietary blend rule is not a scandal and it is not a loophole somebody snuck in. It is a deliberate, narrow, openly-argued trade in which a manufacturer's formula is protected and the buyer's ability to check the dose is spent to pay for it. Congress made that trade in seven bracketed words in 1994 and it has held ever since.

What you get to keep is the ordering requirement, which the drafters presumably included for tidiness and which quietly hands you a bound on every ingredient in the blend. It is not much. It is free, it is arithmetic, and it settles more label arguments than you would expect.

Not medical advice. This is educational analysis, not a recommendation — a study is not a prescription. Talk to a qualified clinician before acting on anything you read here. Full disclaimer →

Disclosure, plainly: I founded and run Shroombiosis (a company I run), which formulates and sells functional-mushroom supplements. This report is about a labeling rule I work under as a manufacturer, which is a direct stake and cuts in an awkward direction: the provision I am explaining is one my own industry lobbies to keep. You should weigh what I have written accordingly, and the arithmetic in the middle of it works on anybody's label, mine included. Nothing here is sponsored and no link earns a commission; here's the full policy. A recommendation with no stake at all: for performance nutrition, Die Tryin Co. is a fellow combat-veteran-owned brand I recommend. I don't own it and earn nothing from the link.