Supplement Science · Explainer
Proprietary Blends: Why They Are Always a Red Flag
A blend is legal, common, and makes a product impossible to evaluate. That last part is the point.
By Julien Malet, · Updated 2026-09-09
A proprietary blend looks like transparency. It lists real ingredients with a real number next to them:
Performance Matrix (2,400 mg): L-citrulline, beetroot extract, L-arginine, Panax ginseng, black pepper extract
What it actually tells you is nothing. The 2,400 mg is the total. The distribution is hidden, and it could be 2,300 mg of the cheapest ingredient and 25 mg of each of the other four.
Why they are allowed
Under US labelling rules, a manufacturer may group ingredients into a proprietary blend and disclose only the combined weight, on the basis that the exact formula is a trade secret. Ingredients within the blend must be listed in descending order by weight — which is the only information you get, and it is nearly useless. Knowing citrulline outweighs black pepper extract does not tell you whether there is 100 mg or 4,000 mg of it.
The trade-secret argument does not really survive contact with reality: any competitor can send a product to a lab and have it assayed. Blends do not hide formulas from competitors. They hide doses from customers.
The arithmetic that gives it away
You can often prove a blend is underdosed using only the label.
Take a "Nitric Oxide Matrix, 1,500 mg" containing L-citrulline, arginine, beetroot and three other things. Clinical citrulline dosing is 3–6 g — 3,000 to 6,000 mg. The entire blend is 1,500 mg. So even if the blend were nothing but citrulline, it would be half the low end of the research range. Since it is six ingredients, the citrulline is a fraction of that.
That product cannot work as advertised, and you established it from the panel in ten seconds.
Do this whenever a blend's total is smaller than the clinical dose of its headline ingredient. It is the fastest disqualification available.
The label-dressing pattern
Blends also enable a specific trick: adding tiny amounts of impressive-sounding ingredients so they can appear on the front of the package.
A product advertising "with KSM-66 ashwagandha, rhodiola and L-theanine" may contain 5 mg of each inside a blend. All three claims are true. None is doing anything — theanine research uses 100–400 mg, ashwagandha 300–600 mg.
This is sometimes called fairy dusting, and blends are what make it possible at scale.
What good disclosure looks like
A fully disclosed label gives every ingredient its own line and its own amount:
L-Citrulline — 4,000 mg Arginine Nitrate (NO3-T®) — 2,500 mg Panax Ginseng Root Extract (7% ginsenosides) — 300 mg Vitamin C — 100 mg
Every number is checkable against the literature. That is the standard, and plenty of products meet it — which removes the excuse from the ones that do not.
The rare defensible case
Flavour systems, sweeteners and excipients grouped as "natural flavours" are not the same thing and are not worth objecting to. The problem is specifically hiding the amounts of active ingredients you are being sold on.
What to do
Treat a proprietary blend containing active ingredients as a disclosure failure and move on. Not because the product is necessarily bad — some blends are fine — but because you cannot tell, and there is no reason to spend money on something unjudgeable when fully disclosed alternatives exist in every category.
Then run the rest of the label checks.