Label literacy

One legal line can hide a dozen doses. Here is how to read a supplement label.

Proprietary blends are legal, common, and easy to catch once you know the tell. The check takes ninety seconds and requires trusting nobody.

Published August 20, 2026 · 11 minute read

There is a line that turns up on a great many supplement labels and looks exactly like information. It reads something close to Performance Blend, 6,200 mg, with four or five impressive ingredients indented underneath it.

It is not information. It is the absence of information, typeset to resemble the presence of information.

The rule that makes it legal

Supplement labels in the United States are governed by 21 CFR 101.36. Paragraph (c) of that section covers proprietary blends, and it is short. A manufacturer may group ingredients under a blend name, declare the total weight of the blend, and list the ingredients inside it in descending order of predominance by weight.

That is the whole obligation. Nothing requires the amount of any single ingredient inside the blend.

Read it again with a calculator in your hand. If a 6,200 mg blend lists citrulline, beta-alanine and betaine in that order, the label is fully compliant whether the split is 2,500 and 2,000 and 1,700, or 6,000 and 150 and 50.

The rule was written for a reason that is not fake. A formula can be intellectual property, and a competitor holding a full quantitative breakdown can copy it over a weekend.

What the argument does not survive is arithmetic. The ingredient list is public. The blend total is public. The only thing a blend actually conceals is the split, and the split is the whole product.

The industry has a name for what hides in there. A recognized ingredient goes in at a dose too small to do what the research says it does, and large enough to print on the front of the tub. Fairy dusting.

The ninety second check

Turn the tub around. Three questions, in this order.

Questions one and two take about ten seconds each. Question three is where most tubs die, and it is worth doing once, properly, because the answer barely changes from year to year.

What the research actually says

The International Society of Sports Nutrition publishes position stands: consensus documents that read the whole body of trials on one ingredient and state a dose. They are free to read, they are updated, and they are boring in the way a reference should be.

Here are three of them, next to what Swolverine prints on the corresponding panel.

Left figure: the range in the position stand. Right figure: the amount per serving printed on the Swolverine panel. Full citations at the foot of this page.

Three ingredients, three consensus documents, three exact landings. That is not a coincidence and it is not marketing either. It is what happens when the dose is chosen from the literature first and the label is printed second.

There is nothing clever about a one line label. That is precisely the point. A one line label has nowhere to hide anything, which is why so few products have one.

The same test on something that cannot be one line

A protein powder has to carry more than one ingredient, so the single line trick is not available to it. Run the arithmetic on the scoop instead.

The Whey Protein Isolate panel gives a serving size of 30.63 g and, further down, 25 g of protein. That is roughly 82 percent of the scoop arriving as protein, before flavor, salt, the enzyme blend and the beet coloring. And a scoop weight printed to two decimal places is a small thing that only turns up when somebody actually weighed it.

Now run the arithmetic on a pre-workout

Pre-workout is where blends live. It is the category with the most ingredients on a panel, the most fanciful names, and by far the most reason to bury a split.

So take the panel at the top of this page and add it up. Eight actives, each with its own figure.

Amounts as printed on the panel. Source: the PRE product page at swolverine.com.

There is no blend line on that panel because there is nothing left to put in one. And you did not have to take anyone’s word for the figure. You added eight numbers off a photograph of a label, which took under a minute, which is the entire idea.

The number that tells you what to do next

Here is the part a blend takes away from you, and it is not the reassurance. It is the ability to act.

PRE prints 3.2 grams of CarnoSyn beta-alanine. The position stand puts the saturation range at 4 to 6 grams a day, sustained for two to four weeks. Because the number is printed, you know exactly what closes that gap: a little over a third of a 5 gram scoop from the standalone tub, on the same day, and you are inside the range the research used.

Try writing that sentence about a product whose label reads Endurance Matrix, 9,700 mg. There is no version of it you could write. You would not know whether you were at 3 grams or 300 milligrams, so you would not know whether to add anything, and if you added something you would not know how much.

This is why people who have been training a long time drift toward single ingredient tubs. Not out of purism. Out of arithmetic.

Three panels, three single lines. A 30 serving tub of creatine at 5 g a scoop works out at 83 cents a day for the only ingredient in it. Prices and serving counts as published on swolverine.com.

The ratio is part of the disclosure

Look again at the first line of the PRE panel: L-Citrulline DL Malate (2:1), 5 g. That parenthesis is doing real work.

Citrulline malate is two compounds bound in a fixed proportion. At 2:1, five grams is roughly 3.3 grams of L-citrulline and 1.7 grams of malic acid. They do different jobs: the citrulline converts to arginine and feeds the nitric oxide pathway behind vasodilation, while the malate enters the Krebs cycle on the energy side.

Print the ratio and any reader can do that division in their head. Leave it off and the same five grams could be almost anything, still legally, still on a panel that looks complete.

Greens powders, where blends usually go to hide

If pre-workout is where blends live, greens powders are where they breed. Twenty seven superfoods sounds better on a front label than any single honest number one of them could carry, and the blend rule was practically designed for the sentence.

Swolverine’s Greens + Reds groups its ingredients as well. It just groups them the other way round: the header carries a total and every line underneath carries its own amount, so the header is a sum rather than a substitute.

Add them yourself. The header figure is the sum of the seven lines beneath it. Same for the enzyme block further down the panel: MCT oil powder 100 mg, papain 25 mg, protease 25 mg, BioPerine 5 mg, header 155 mg.

The claim, and what has to back it

Swolverine publishes this comparison on its own product pages. Anyone can print a chart like it. What makes it checkable is that everything in the right hand column is a claim about a document, and every one of those documents is public.

Past the panel: what came out of the blender

A Supplement Facts panel tells you what a manufacturer intended to put in the tub. It says nothing about what actually came out of the blender, and the gap between those two things is where the category’s real scandals have always lived.

That gap is what a certificate of analysis closes. Swolverine keeps a public page of them, indexed by lot number. You turn the tub over, read the lot code off the bottom, and match it against the list. Testing is attributed to Lief and Micro Quality Labs, described as an ISO/IEC 17025 accredited laboratory, with Lief listed as an NSF and FDA inspected facility for Good Manufacturing Practices compliance.

There is a second page most brands in this category do not have at all. Proposition 65 obliges companies selling into California to warn about heavy metal exposure; it does not oblige anyone to say how much. Swolverine publishes the measurements: four metals, in micrograms per serving, across twelve products.

One product out of twelve on the page, given as average values from multiple batch tests by ISO 17025 certified third party laboratories. Source: the Prop 65 Heavy Metals Transparency page at swolverine.com.

Publishing a warning is compliance. Publishing the measurement is a different act, and it is the one that lets a reader decide for themselves rather than be reassured.

What to do with the next tub you pick up

None of this requires you to change brands, and none of it requires trusting the person writing it. It requires turning a tub around and running three questions.